Fib Model Code 2020: Towards A General Code For Both New and Existing Concrete Structures

 

Received Rece ived:: 6 Decembe Decemberr 20 2017 17

Accepted Accepted:: 2 22 2 De Decem cember ber 2017

DOI: 10.1002/suco.201700198 10.1002/suco.201700198

T EC H NI CA L P A P ER

 fib  Model Code 2020: Towards a general code for both new and existing concrete structures Stuart Matthews1 | Agnieszka Agnieszka BigajBigaj-van van Vliet  Vliet 2

| Joost Walraven Walraven3 | Giuseppe Giuseppe Mancini Mancini4 |

Gerrie Dieteren2 1

Building Technology Group, Building Research

Discussions have been underway in  fib  (Fédération Internationale du Béton) about  advancing the  fib  Model Code for concrete structures. These include the  fib  international workshop in The Hague (June 2015), the  fib  MC2020 Core Group meeting in Madrid (December 2015), and a series of follow-up worldwide consultations on the  fib  ambition regarding the new developments in structural codes, including the special session on Model Code in the   fib  Symposium in Maastricht (June 2017). This paper discusses the main aspects of the development of  fib  MC2020, which is envisaged as a single-merged general code fully integrating the provisions for the design of new concrete structures with matters relating to existing concrete structure. It needs to deal effectively with both the design of structures and all the activities associated with the through-life management of existing concrete structures, including matters such as their in-service assessment and interventions upon them. To that end, MC2020 will take sustainability as a fundamental requirement, based upon a holistic treatment of societal needs and impacts, life-cycle cost and environmental impacts. This paper discusses the main aspects of the development of   fib MC2020. As part of this, the envisaged contribution of   fib   T10.1: Model Code 2020 is reviewed. However, recognizing the overall ambition of the   fib  MC2020 project, it is clear that all   fib  commissions, along with other bodies able to make contributions on relevant topics, will need to work together to assemble the breadth of knowledge and expertise which will be required for the  fib  MC2020 project.

Establishment Establishm ent Ltd, Hertfordshire, UK  2

Buildings, Infrastructure and Maritime, TNO,

Delft, The Netherlands Netherlands 3

Faculty of Civil Engineering and Geosciences,

Delft University of Technology, Delft, The Netherlands 4

Faculty of Civil Engineering, Engineering, Politechnico di

Torino, Turin, Italy Correspondence

Agnieszka Bigaj-van Vliet, Buildings, Buildings, Infrastructure and Maritime, TNO, PO Box 155, NL-2600 AD Delft, The Netherlands. Email: [email protected]

KEYWORDS

conservation, general structural code for concrete structures, interventions, Model Code, structural assessment, structural design, through-life care of concrete structures

1   |   INTRODUCTION

Discussions have been under way for some time in  fib  about  advancing the   fib   Model Code for concrete structures. Following publication of the final version of  fib Model Code for  concrete structures 2010 (MC2010)   1, a series of explanatory Discussion on this paper must be submitted within two months of the print  publication. The discussion will then be published in print, along with the authors' closure, if any, approximately nine months after the print publication.

Structural Concrete.   2018;1–11.

 

articles was published in the   fib   Journal  Structural Concrete in the four editions printed in 2013, with these articles being written by the authors/representatives of the groups of contributors to the relevant parts of  fib  fib  Model Code 2010. These articles provided a variety of background information, additional explanation, research findings, and illustrative application examples that it was not possible to include in the text of   fib   Model Code 2010. There have also been a number of  otherr pape othe papers rs publishe published d in   Structural Concrete   over recent 

wileyonlinelibrary.com/journal/suco

 

© 2018  fib . International Federation for Structural Concrete

 

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MATTHEWS  ET AL.

 fib  Model Code 2010. These years which concern the use of  fib have all contribut contributed ed to a growing growing pool of knowledge knowledge and experience experie nce about designing designing and constructing in accorda accordance nce with the provisions of   fib   Model Code 2010. Additionally, these activities and the continuing research work have helped to identify where improvements/modifications to   fib   Model Code 2010 are desired and possible, in particular, regarding the extension of the current code provisions for matters relating to existing concrete structures. structures.

Rotterda Rotte rdam, m, April April 2016), 2016), the JCIJCI- fib   Joint Joint Worksh Workshop op on Codes for Existing Structures (Tokyo, September 2016), the  fib  Model Code 2020 workshop held in association with the  fib   Symposiu Symposium m in Cape Town (Novemb (November er 2016), and the special session on Model Code during the  fib  Symposium in Maastricht (June 2017) confirmed that further work remains to be done to take coverage in the  fib  Model Code for concrete structures beyond the point where work reached with  fib  MC2010. An important aspect of these the publication of  fib

The opport opportuni unity ty to advanc advancee   fib   Mode Modell Code Code 2010 2010 became beca me apparent apparent to   fib   Special Special Activity Group (SAG (SAG)) 7:  Assessment and interventions upon existing structures, now  fib   Commissio Existing concrete concrete structures structures   (COM3), Commission n 3:   Existing which led to presenting the initial idea to create a model code for the assessment of existing structures to complement  the existing  fib  MC2010. During the debate in the Technical Council meetings held in Copenhagen in May 2015 it was considered more appropriate to work toward a single merged  fib   Model Model Code for concrete concrete struct structures ures dealing with both new and existing structures. Consequently, a decision was made to hold a workshop to discuss the concept of such a  combined comb ined code and its requ required ired attribut attributes. es. The workshop workshop

 fib activities is sensing the worldwide readiness of the wider  fib community to undertake the challenging and ambitious task  of preparing the next generation of the  fib  Model Code. The future   fib   commiss commission ion work work alo along ng wit with h the the thema matic tic   fib worksh wor kshops ops to be held held worldworld-wid widee are are env envisa isaged ged to help help resolve exactly how radical the approach should be and what  should be integrated into such a general structural code. In October 2016,   fib   T10.1: Model Code 2020 held its first meeting in Lausanne, where the focus was on formulat fib  Model Code 2020 and scope ing vision and objectives for  fib of the T10.1 work and to decide on the timeline of delivering and disseminating Model Code to the engineering community worldwide. Recognizing the overall ambition of the   fib

was hosted by TNO in The Hague on June 30, 2015, with over 40 attendees, including invited speakers representation all   fib   commissions and those active in other professional organizations, bringing perspectives from across the globe and discussing many topics including:

MC2020 project, it was emphasized that all  fib   commissions, along with other bodies able to make contributions on relevantt top van topic ics, s, will will need need to work work toget together her to asse assembl mblee the breadth of knowledge and expertise which will be required for the  fib  MC2020 project. It is therefore envisaged that all  fib commissions along with members of the wider  fib  family will contribute to the drafting of   fib  MC2020. In particular, given give n the ambition ambition of produ producing cing an inter internati national onally ly recogrecognized code, a strong involvement of all national groups and more inclusive representation of all main geographic regions are aimed at and liaison/coop liaison/cooperat eration ion is being sought sought with other international organizations working on relevant topics. Further details about the current and future activities of  Task Groups T10.1 may be found on the  fib  website (www. (www. fib-international.org/comm-a-tgs).

  general concepts for future mode modell code advancement, •  fundamental principles and reliability concepts for new and existing structures, •   mo mode dels ls an and d mate materi rial al char charac acte teri riza zati tion on for for exis existi ting ng structures, •   inspec inspectio tion, n, maint maintena enance nce,, and ret retrof rofitt itting ing of existi existing ng structures, and

•

•

  evaluation of decision-maki decision-making ng about and management of  existing structures. structures.

The worksh workshop op outcom outcomes es se sett dow down n ide ideas as for possi possible ble ways forward and confirmed the aspiration for developing integrat inte grated ed provisions provisions for new and exis existing ting conc concrete rete structures. These were further developed by the  fib  MC2020 Core Group set up by the   fib  Presidium, which was tasked with considering the factors relevant to the preparation of a single merged general code that fully integrates the provisions for  the design of new concrete structures and matters relating to existing concrete structures, including situations where new struct structura urall me membe mbers rs are are inc incorp orpora orate ted d as par parts ts of existi existing ng

2   |   N E E D FO R M O D E L C O D E ADVANCEMENT

structures, together with developing a route map for achieving this goal. After meeting in Madrid in December 2015, the  fib  MC2020 Core Group proposed a roadmap outlining a  potential course forward in this project. Discussions at the recent follow-up meetings such as at the   fib  Belgian Colloquium qui um and the   fib   Netherlands Netherlands Colloquiu Colloquium m (Brussels (Brussels and

improvem improv ement entss and fur furthe therr dev devel elopm opment ent and ide identi ntifyi fying ng chances and opportunities to do so is a part of  fib's  task associated with its mission of assisting engineers, practitioners and researchers in their work (see Walraven   2). With respect  to development of Model Code 2020, three main application doma domain inss are are to be cons consid ider ered ed,, name namely ly new new conc concre rete te

At the time of its launch, the  fib  Model Code 2010 was (and still is) the most comprehensive code on concrete structures, addressing matters concerned with their complete life cycle: conceptual design, dimensioning, construction, conservation, and dismantlement. At the same time,   fib  aims to be at the frontier fron tier of the prenormal prenormalizat ization, ion, which which implies implies continuous continuous pionee pio neerin ring g wor work k in cod codif ifica icatio tion. n. Recogn Recognizi izing ng nee needs ds for 

 

MATTHEWS   ET AL.

 

structures created with contemporary materials, design and construction practices, new concrete structures making use of novel materials, materials, design and cons construc truction tion practices practices and existing concrete structures utilizing a variety of old materia rials, ls, design designs, s, and con constr struct uction ion pra practi ctices ces.. Each Each of the these se domains has its specific needs and opportunities with regard to code advancement, and treating these needs in a consistent way for all domains will be a major improvement in the Model Code provisions.

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of construction used (see Figure 2). These calls for reflection on the treatment of the novel materials and on the guidance provided on how to deal with the evolution of materials in structural codes, so they have provisions which are able to accommodate further developments in the future (see Dehn and Herrmann   5). With regard to existing concrete structures, it is generally recognized that: •

With regard to new concrete structures, the main concern is the improvement of their performance, quality and competitiveness, compared to other types of engineering solution tions. s. Th This is impl implie iess a ne need ed for for opti optimi mizi zing ng desi design gn and and construc cons truction tion procedures procedures,, enabling enabling use of fitfit-forfor-purpo purpose se solutions and improving environmental performance, energy efficie effi ciency ncy and cost-eff cost-effecti ectivenes venesss of cons construct truction ion technolo technolo-gies appropriate to the whole life-cycle of the structures. It  has been recognized that with the current state of knowledge significant steps can be made to improve the in-service performance of structures (see Sakai et al.   3) and to inco incorpora rporate te efficiently and effectively the through-life management strategy by considering this at the design stage (see Matthews

  They are appreciably different entities to the new concretee structur cret structures es whic which h conte contempora mporary ry desi design gn and constru struct ctio ion n prac practi tice cess crea create te and and th that at th thee di diff ffer eren ence cess generall gene rally y rela relate te to the age/peri age/period od when the structur structures es were constructed, the implicit assumptions contained in the codes used for their design, and in the supporting material/product standards of those earlier times. •   They are composed of materials with different charactercharacteristics to those employed in contemporary concrete structures. While the specified concrete strength was typically much mu ch lo lowe werr th than an th that at empl employ oyed ed to toda day, y, th thee actu actual al strength can be significantly higher depending upon the extent of subsequent in-service hydration (of the coarse

et al.   4). Obviously, sustainability, through-life management  and life cycle perspective are important considerations for  existing structures; however some additional issues apply as well, as discussed further below. A particular need for advancement of the Model Code has to do with the increasing development and use of novel cementitious materials with alternative binders, various types of fibers, and other forms of modification. Figure 1 illustra trates tes the tr treme emendo ndous us inc increa rease se in concr concrete ete compre compress ssive ive strength that has occurred since about 1950, and identifies the various descriptions that have been assigned to the concretes associated with these changes. It can be observed that  there is strong tendency toward developing materials with

cement particles present).   Their actual actual nature nature and conditio condition n can be inves investiga tigated, ted, allowing a prognosis to be made about their future condition and performance. However, investigations can be difficult to undertake and leave significant uncertainties to be addressed in the structural assessment process. •   Existing Existing structur structures es may have experienced experienced damage damage or  deterioration—it is important to establish what the influence will be upon the current and future characteristics of the concrete and steel. This may be an essential first  step toward making structure management and intervention decisions for an existing structure. •   Certain structural structural materials and components are not used

enhanced strength characteristics. Also as time has passed, we observe an increasing diversity in the materials and forms

anymor any more, e, such such as pla plain in or ind indent ented ed rei reinfo nforci rcing ng ste steel. el. Consequently, most modern codes and recommendations are based on the assumption assumption that standardize standardized d ribb ribbed ed reinf reinforc orcing ing steel steel bars bars are use used d as rei reinfo nforc rceme ement nt and, and, accordingly, do not include provisions for use or evaluation of prev previous ious types of rein reinforc forcing ing material materials. s. Thus, modern design rules can have limited applicability for  use in the assess assessment ment of older existing existing stru structur ctures es and therefore should be applied with care. •   Some past past struct structura urall mat materi erials als,, such such as hig high h al alumi umina  na  cement cem ent concrete concrete (HAC (HACC)/c C)/calc alcium ium aluminat aluminatee cement  cement  concrete, are not generally used anymore for structural purposes because they had certain unfavorable character-

350

RPC, UHPC: c.2000s

   ] 300   a    P    M    [ 250    h    t   g   n 200   e   r    t   s   e 150   v    i   s   s   e   r 100   p   m   o 50    C

HPC: c.1990s

NSC: 1970-1980 1970-1980ss

MC 2010

NSC: c.1950s MC 1990

0 0.1

0.2

0.3

0.4

0.5

0.6

0.7

Water-binder ratio [-]

FIGURE 1   Developme Development nt of concrete compressive compressive strengt strength h with time since

about 1950. Expressed in terms of mean concrete cylinder compressive strength (courtesy: Harald Müller). NSC, normal strength concrete; MC 1990, CEB-FIP Model Code 1990; HPC, high-performance concrete; MC 2010,  fib  Model Code 2010; RPC, reactive powder concrete; UHPC, ultrahigh performance concrete

•

istics. In the case of HACC, due to chemical processes, it oft often en experi experienc enced ed a red reduct uction ion in it itss compre compressi ssive ve  7 strength while in service (see Neville ). •  Depending upon the period of their construction, many existing structures may contain obsolete structural details which whi ch wil willl actua actually lly produc producee subopt suboptimu imum m behavi behavior or in

 

 

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MATTHEWS  ET AL.

Mate rial al and and/o /orr for form m of of con const stru ruct ctio ion n Materi

Peri Pe riod od of av avai aila labi bilit lity y / maj major or use use in th thee UK UK (de (dens nsit ity y of of shad shadin ing g indi indica cate tess ext exten entt of of use use))

Cement and concrete based materials

1700

1750

1800

1850

1900

Mass concrete: lime or pre-Portland cement based Mass concrete: Portland cement based Clinker aggregate concrete in 󿬁ller joist 󿬂oors Reinforced concrete: early patent systems Reinforced concrete Precast concrete Pre-tensioned concrete Post-tensioned concrete Lightweight structural concrete, blocks and screeds Asbestos-󿬁bre-reinforced cement sheet materials Glass-󿬁bre-reinforced cement (cladding & permanent formwork) Other-󿬁bre-reinforced concretes (screeds & ground 󿬂oors) Polymer-󿬁bre-reinforced concrete

respect of failure modes associated with shear, punching, and torsion in some regions of the structure. Clearly the implications of such structural details need to be evaluated. However, this is not always an easy undertaking and work needs to be undertaken in MC2020 to provide assessment guidance that enables proper consideration of  the the ac actu tual al stru struct ctur ural al deta detail ilin ing g of exis existi ting ng conc concre rete te structures.

3   |   V I SI O N A N D O B JE C T I V E S FO R  R  F I B M O D E L C O D E 2020

1925

1950

1975

2000

2010

FIGURE 2   Indicativ Indicativee usage of ceme cement  nt  and concrete materials/forms of  construction in the United Kingdom  (ISE  6 ). The density of shading indicates the intensity of usage in that  period. Heavier shading indicates the more intense usage

of sus susta taina inabil bility ity when when dea dealin ling g with with new and existi existing ng concrete structures; •   a model code that will take sustainability sustainability as a fundamental requirement, based upon a holistic treatment of societal needs and impacts, life-cycle cost and environmental impac imp acts ts.. These These ove overa rarch rching ing requi requirem rement entss wil willl have have defi defini ning ng impl implic icat atio ions ns for for su subs bsid idia iary ry perf perfor orma manc ncee requirements critical to structural design and assessment  procedures. These are matters such as human and environmental safety, serviceability and durability, and other  specific performances such as the robustness of the structure and the resilience of its functionality; •   a model code that follows an integrated life cycle per-

fib  MC2020 is to go beyond the point reached The vision for   fib by   fib  MC2010, recent ISO codes, such as ISO 16311, and the current Eurocode activities to extend the application of  Eurocodes to existing structures.   fib  MC2020 is envisaged as an ambitious project that would build upon the achievements of  fib  fib  MC 2010 and its holistic treatment of activities for the desi design, gn, construc construction tion,, conserva conservation, tion, and dismantl dismantleement of concrete structures. The goal is that such a single merged mer ged code code would would fully fully int integr egrat atee the guidel guideline iness for the design des ign of new concr concrete ete struct structure uress wit with h tho those se rel relati ating ng to existing concrete structures, also recognizing the fact that the differen diff erentiat tiation ion betw between een new and exis existing ting stru structur ctures es is not  always easy to achieve, particularly during/after the adapta-

spective which promotes a holistic treatment of; •   a model code with a safety philosophy based on reliability concepts, that takes advantage of better knowledge and understanding of uncertainties and of the risk acceptance and risk differentiation concept for both new and existing structures; structures; •   a model code that consequently makes use of the performance based concept to close the gap between material engineers and structural engineers and to remove specific constraints for novel types of concrete and reinforcing materials; •   a model code with provisions based on rational, physically cally correc correctt and app approp ropria riatel tely y gen genera eraliz lized ed mod model els, s,

tio tion n of exi existi sting ng str struct ucture uress for new per perfor forman mance ce requi require re-ments. It is anticipated that the format and contents of   fib MC2020 MC202 0 will evolve to suit these forward-look forward-looking ing obje objecctives, dealing both with the design of new structures and all the activities associated with the through-life management of  existing exis ting conc concrete rete structu structures res including matters such as inservice assessment and interventions upon them, including situations where new structural members are incorporated as parts of existing structures. The numerous aspirational goals that have been identifie fied d for   fib   MC2020 MC2020 in the vari various ous tech technica nicall disc discussi ussions ons include that ideally it should be:

allowing for implementation of the level of approximation approach for both the design of new structures and all the activities associated with the through-life management of exis existing ting concrete concrete structur structures es incl including uding matt matters ers such such as in in-s -ser ervi vice ce asse assess ssme ment nt and and in inte terv rven enti tion onss upon them; •   a model code that allows full advantage to be taken of  information that can be acquired by (in situ) testing and monitorin moni toring g of exis existing ting structur structures, es, for the throu through-li gh-life fe managemen mana gementt of exis existing ting concrete concrete stru structur ctures es incl including uding prediction and updating of reliability and durability of  deteriorating deteriorat ing structures; structures; •  a model code that recognizes the importance of robust-

•

  a model code that includes worldwide knowledge with respect to materials and structural behavior and recognizes the needs of engineering communities in different  regions of the world; •   a model code that reflects the importance of sustainability and provides guidelines for the consistent treatment 

ness and redundancy for respectively new and existing structur stru ctures, es, and offers offers cons consiste istent nt treatme treatment nt of thos thosee in (conceptual) design, through-life management and associated activities such as assessment; •   a model code that reflects the importance of sustainability approa approach ch and provid provides es gui guidel deline iness for con consis sisten tent  t 

 

MATTHEWS   ET AL.

 

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treatment of sustainability demands to new and existing concrete structures; structures; •   a mode modell co code de th that at gi give vess part partic icula ularr atte attenti ntion on to the the is issue suess spec specif ific ic fo forr exis existi ting ng stru struct cture ures, s, such such as the the eff effect ect of mat materi erial al degrada degradatio tion n and and/or /or ins insuff uffici icient ent or  deficient detailing on the provided material and member behavior models, the need for model improvement  an and d th thee trea treatm tmen entt of unce uncert rtai aint ntie iess in mo mode dels ls and and model parameters parameters for exist existing ing struct structures ures and (phased) (phased)

Recognizing the overall ambition of the  fib  MC2020 pro ject, it is clear that all   fib   commissions, together with other  bodies bod ies who are worki working ng on relev relevant ant topic topics, s, will will need need to work wor k tog toget ether her to asse assembl mblee the breadt breadth h of kno knowl wledg edgee and expertise which will be required for the  fib  MC2020 project. It is envisaged that all  fib  commissions along with members of the wider   fib  family will contribute to the drafting of   fib MC2020. In particular, it is proposed that the contributing group should provide a more inclusive representation of all

interventions; •  a model code that adopts through-life management, and recognizes the decision making processes for the management of existing structures and undertaking interventions upon them, and the effect of (phased) interventions on the structural behavior and service life expectations; •   a model code that gives particular attention to new types of con concr crete ete and new techn techniqu iques es for constr construct uction ion and (r (rem emed edia iall and and enha enhanc ncem emen ent) t) inte interv rven enti tion ons, s, whic which h includes defining test methods and creating a framework  for testing and performance evaluation of concrete with supple sup plemen menta tary ry bin bindin ding g mater materia ials ls and nov novel el typ types es of  aggregates;

main geographi geographicc regi regions ons (Africa, (Africa, Asia Asia,, Australi Australia, a, Euro Europe, pe, North America, and South America) to bring insights that  would not otherwise be gained. Additionally, it is proposed that liaison/coope liaison/cooperati ration on will be sought sought with other inte internarnational tion al organiza organizations tions working working on relevant relevant topic topics, s, incl including uding bodi bodies es such such as CE CEN, N, IS ISO, O, JC JCI, I, ACI, ACI, PC PCI, I, JC JCSS SS,, and and RILEM. It is also foreseen that contacts with international organizations will be developed and maintained via various mechanisms including holding of joint events, which could act as an important stimulus to participation in the work on various topics and as a basis to explore the range of technical practice employed in various regions and by different professional groups. However, the specifics of these involvements and interactions go beyond the scope of this paper. It is also recognized that an important objective would be to present detailed background technical information in supporting   fib  bulleti  bulletins, ns, pref preferab erably ly with these these publi publicati cations ons being developed and made available as work on  fib  MC2020 progresse progr esses. s. Idea Ideally lly the developme development nt of backgroun background d documents would enable continuous dissemination of up-to-date results to other bodies that wish to adopt the   fib   MC2020 concepts, and would also provide for timely feedback in the final stage of harmonization of  fib  fib  MC2020. Finally, consideration will need to be given to new ways of deli deliveri vering ng   fib   MC2020, MC2020, with modern modern (digi (digital) tal) delivery delivery being foreseen alongside the traditional hardbound book format. A digital digital delivery delivery form format at would would faci facilita litate te subseque subsequent  nt  maintenance and evolution of  fib  fib  MC2020. It could also help further furt her develop develop   fib's   knowledge knowledge diss dissemin eminatio ation n process process,, working in coordination with  fib  Commission 9:  Dissemination of knowledge.   This would allow   fib   to reach a larger  audience, as well as potentially allowing efficient periodic adjustments to be made to the technical content of the   fib

•

  a model code that consistently treats the end-of-servicelife life issue issuess such such as dem demoli oliti tion on and dispos disposal al includ including ing safety level for dismantling and structural aspects of dismantlement, and finally; •   a model code that is oriented toward prac practical tical needs, provides guidelines to the practitioners when provisions in regular standards are deficient or lacking, and can serve as a reference for engineering standards worldwide.

As part of the discussion on the content of the  fib  Model Code 2020, the question has arisen about the form that such a general structural code would take. It has been suggested that that succ succes esss migh mightt be po port rtra raye yed d diag diagra ramm mmat atic ical ally ly by Figuree 3a, with extensive Figur extensive general general provi provision sionss being shared for for appl applic icat atio ions ns for for bo both th new new and and exis existi ting ng stru struct ctur ures es,, whereas wher eas an ineffec ineffective tive formulat formulation ion migh mightt be portr portrayed ayed as shown in Figure 3b (Denton 2015). Further discussions will be needed to resolve how radical the approach should be to creating a general structural code for both new and existing concrete structures. structures.

FIGURE 3   (a) Succ Successful essful future general

structural code with extensive shared general provisions and (b) Ineffective Ineffective future general structural code with limited shared general provisions provisions (courtesy: Steve  8 Denton from  )

 

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Model Code for concrete structures as future developments occurred.

4   |   ADVANCEMENTS IN N   F I B   M O D E L C O D E 2020

The above mentioned selected aspects make clear that signif nifica icant nt improve improvement ment is nee needed ded and may be ach achiev ieved ed in the the gu guid idan ance ce avai availa labl blee for for the the de desi sign gn and and stru struct ctur ural al assessment of the vast portfolio of existing concrete structures which form the diverse range of buildings and infrastructure that we all rely on during our day-to-day lives. In the the follo followi wing ng some some of the the ma main in ar area eass ident identif ifie ied d for  for  improvement improve ment are discussed, discussed, showing examples examples of technitechnical procedures required modification modification to support advanced design and effective assessment of existing concrete structure turess iden identi tifi fieed nu nume mero rous us asp spec ects ts that that need need to be addres add ressed sed.. Additio Additional nal points points to those those mentio mentioned ned below below and and furth further er deta detail ilss to th those ose incl include uded d in the pro provis vision ional al Table of Contents of the   fib   Model Model Code 2020, 2020, are currently under review by   fib   T10.1. As one component of the activities to take forward this work, the   fib   T10. work, T10.1 1 meet meetin ing g in Delf Delftt in Ma Marc rch h 2017 2017 endors end orsed ed the ide ideaa of settin setting g up MC202 MC2020 0 Actio Action n Gro Groups ups focusing on specific technical topics. Currently the following Action Groups are envisaged: AG1 Action Group Databases AG2 Action Group Shear and Punching AG3 Action Group Bond AG4 Action Group Durability and Service Life Prediction AG5 Action Group Detailing AG6 Action Group Fire AG7 Action Group Seismic Design and Assessment  AG8 Action Action Gro Group up Nonlin Nonlinea earr Finite Finite Ele Elemen mentt Modeli Modeling ng (AG: NL FEM) AG9 Action Group Structural Health Monitoring and Testing (AG: SHM and Testing) AG10 Action Group Robustness AG11 Action Group Fatigue AG12 Action Group Impact and Explosion The vision for the MC2020 Action Groups is that they will draw together knowledge and expertise in their selected technical topic areas, both within and outside  fib, as is appropri priate ate.. Accord According ingly ly the they y will will com common monly ly add addres resss topics topics which whic h several several   fib   commissions/  fib   Task Task Groups Groups have have an interest in and therefore will have a need to collaborate in the development of the relevant contributions to MC2020. Thus the Action Groups are expected to address wider or  generic gene ric issues. issues. Acco Accordin rdingly gly they are expected expected to provi provide de input across MC2020 and therefore may well need to deal with philosophical points which require wider consideration tha than n is perhap perhapss neces necessar sary y for contr contribu ibutio tions ns to a sin single gle section of MC2020.

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4.1   |   Sustainability perspective

MC2020 MC20 20 prov provid ides es an im impo port rtan antt oppo opport rtun unit ity y to furt furthe her  r  advance adva nce our appr approach oach to the sustaina sustainable ble design, design, construc construc-tion, and through-life care of concrete structures. Central to this this will will be how how we form formul ulat atee and and veri verify fy perf perfor orma manc ncee requirements for concrete structures within a holistic sustainability framework utilizing the widely accepted   “three pillars of sustainability sustainability”  of social, environmental and economic performance. Such an approach provides a way to recognize the greatt benefits grea benefits conc concrete rete structur structures es provide provide to human humankind' kind'ss global society, along with their impacts on that society and the wider environment, as well as their economic cost and return. Adop Adopti ting ng th this is in inte tegr grat ated ed li life fe-c -cyc ycle le appr approa oach ch,, th thee requirem requ irements ents for soci social al performa performance nce would have defi defining ning implications implicatio ns for subsidiary performance requirements critical to struc structura turall design design and asse assessm ssment ent procedure procedures. s. These are matters such as human and environmental safety, durabili bility ty,, serv servic icea eabi bili lity ty and and ot othe herr so soci cial al aspe aspect cts, s, such such as esthe estheti tics, cs, adapta adaptabil bility ity and mai mainte ntenan nance ce.. Based Based upo upon n the wider social context, there may be requirements for specific performa perf ormances nces such as the robustne robustness ss of the structu structure re and the resilience of its functionality. There is ongoing debate about how these aspects, along with the verification of the associa associated ted perf performa ormance nce requ requirem irements ents,, might be best dealt  dealt  with in the organization organization of MC2020. MC2020. Whil Whilee the approach approach adopted adopt ed has to be phil philosophi osophicall cally y robust, robust, its impleme implementantatio tion n nee needs ds a pra pract ctica icall and conven convenie ient nt method methodolo ology gy for  its use. Sustainable design of concrete structures should aim at creating satisfactorily reliable structures which meet the specified demands for safety, serviceability, and durability for a defined number of years in an environmentally acceptable manner at a  suitable through-life cost. The Model Code needs to support  the creation of structures with reduced environmental impact  by facili facilita tatin ting g the effici efficient ent and and mod modera erate te use of nat natura urall resourc resources, es, with the producti production on of les lesss wast wastee and pollu pollution, tion, which support economic prosperity and vibrant social development. Good example of effective extension of the use of the structures after adaptation to the new faction can be found in Va Van n Nel Nelle le factor factory y Rot Rotter terda dam m which which is sti still ll fit for use after  after  structural and architectural readaptation (Figure 4). 4.2   |   Through-life managem management ent of concrete st structures ructures

The treatment of the through-life management of concrete structures, a topic introduced in MC2010, will be evolved to suit the broa broader der circ circumsta umstances nces of appl applicat ication ion of MC20 MC2020. 20. Conceptually Conceptu ally through-li through-life fe mana manageme gement nt seeks seeks to inte integrat gratee issues relating to the design and construction of new concrete structures with those required for the management of  existing concrete structures throughout their service life. It is expected that adequate through-life management of existing structures will enable optimization of life cycle cost of the

 

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Suitable Suitab le qualit quality y manag manageme ement nt proces processes ses are req requir uired ed throughout thro ughout the design design and cons construct truction/i ion/inter ntervent vention ion stag stages es to ensure that the structure will comply with the specified performance requirements, including being adequately durable. A component of such quality management is the prepara ratio tion n of a Bir Birth th Ce Certi rtifi ficat catee Docume Document nt contai containin ning g al alll the relevant data to allow effective and efficient management of  the structure throughout its life cycle. An aspect of through-life management is the implementati tation on of th thee cons conser erva vati tion on and and ma mana nage geme ment nt stra strate tegi gies es defined during design. This requires processes by which the condition condi tion of existing existing conc concrete rete structu structures res can be eval evaluate uated d and interventions undertaken. These activities may include monito mon itorin ring, g, inspec inspectio tion, n, making making asses assessme sments nts,, possib possibly ly restricting restrict ing usage, performing maintenance and undertaking interventions to extend service life and/or meet new performance requirements, as appropriate. Accordingly the provisions necessary for the successful through-life management of concrete structures need to be identi identifie fied d dur during ing the con conce ceptu ptual al design design sta stage. ge. For man many y structures these considerations might focus on longevity and durability provisions to ensure that the minimum required

FIGURE 4   Built in 1930 Van Nelle fact factory ory Rotterda Rotterdam m is still fit for us usee

after structural and architectural re-adaptation to a new function (source: https://www.flickr.com —Nanette de Jong)

safety and performance levels are respected for the relevant  Limit States. However, for some structures these considerations atio ns migh mightt include include addr addressi essing ng matt matters ers such as resilie resilience nce and recovery recovery from exce exception ptional al events, events, such as tsun tsunamis amis,, severe earthquakes, or other potential causes of major damage, as well as postevent functionality requirements. 4.3   |   Fundamental reliability principles

structures. This is a challenge often faced in the engineering pract pra ctice ice,, which which ca can n be ill illust ustrat rated ed by an exampl examplee of Krk  Bridge, Brid ge, Croatia Croatia where the associated associated costs of the maintenance and repair works in a period of less than 30 years' service amounted to some 25% of the cost of construction of  the structure (see Figure 5).

FIGURE 5   Krk B Bridge, ridge, Croatia, general view, and illustration of deterioration: the associated costs of the maintenance and repair works in a period of less than 30 years' service amounted to some 25% of  the cost of construction of the structure

Overalll the Overal there re are many many con consid sider erati ations ons whi which ch nee need d to be incorpora inco rporated ted with within in MC2020 MC2020 for sele selectin cting g an appro appropriat priatee struc st ructur tural al relia reliabil bility ity le level vel for ei eithe therr a new or an existi existing ng structure. The selection the structural reliability level to be adopted in Model Code 2020 needs to take into account in a  comprehe comp rehensive nsive way the important important differen differences ces whic which h exis exist  t 

 

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betwe between en the circum circumst stanc ances es of new constr construct uction ion and the assessm asse ssment ent and exte extensio nsion n of life of existing existing building buildingss and other constructed assets. Recognizing the world perspective that is being adopted for the Model Code 2020, the envisaged approach involves the selection of an appropriate structural reliability level early in the design process which will take into account not only these types of factors, but also other issues issues such as those raised raised by developin developing g count countries ries relating to the local (national or regional) selection of appropriate reliability levels to be used in design and/or structural assessment relative to their economic level. There The re is the need need to rec recal alibr ibrat atee the target target rel reliab iabili ility ty levels accounting for the economic constraints and sustainability abil ity consider consideratio ations ns associa associated ted with exis existing ting structur structures, es, while respecting the generally accepted risk levels relating to the loss of human life adopted adopted for new structur structures. es. Target  reliabil reli ability ity leve levels ls shoul should d also be modified modified for monumenta monumentall buildings taking into account not only their status as existing structures, but also that their operation and use might also be assisted by the implementation of active and/or passive monitoring and safety management systems, so that their consequence class can be reduced by limiting the risk for human life by mea means ns of appr appropria opriate te control control measures measures and procedures. It is proposed that structural robustness will be treated at a metric level by definition of a specific  β -value, -value, so allowing for its correct quantification. The inc inclus lusion ion of existi existing ng struct structure uress withi within n the new Model Code will require the management of new types of  uncertai unce rtaintie nties, s, of an epistem epistemic ic nature, to cove coverr the lack of  knowledge of their structural configuration and some aspects of their structural behavior. Such specific uncertainties cannot be treated at an aleatoric level but may require use of  event tree and Bayesian approaches, which are not usually employed in the design of new structures. General Gene ral provisions provisions for the trea treatmen tmentt of model model unce uncerrtainti tainties es rel relate ated d to the defini definitio tion n of em empir pirica icall and sem semiiempirical resistance models will be given, with the scope to achieve better uniformity in their reliability level.

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Also for the assessment of existing structures, the determination mina tion of the properti properties es of the stru structur ctural al material materialss and their corresponding constitutive relations is an indispensable step in the process leading to conclusions and decision making. ing. Also Also here here th thee defi defini niti tion on of su suit itab able le me meas asur urem emen ent  t  methods, to be used both at the site and in the laboratory, is required. Moreover attention should be given to the properties of  older old er type typess of materi materials als,, lik likee plain plain reinfo reinforci rcing ng bar bars, s, whi which ch have practically been ignored in modern code recommendations, but are again highly relevant in relation to the assessment of existing structures from different eras of construction. Finall Fin ally, y, meas measure uremen mentt method methodss have have to be def define ined d in order to determine the properties of structural materials in existing structures subject to deterioration. In all cases where material properties are measured, both the mean values and the coefficient of variation have to be determined, for the sake of the assessment of structural reliability.

4.4   |   Contemporary, recent, old, and innovative materials

Up to no now w conc concre rete te prop proper erti ties es have have ge gene nera rall lly y been been expressed as a function of the concrete compressive strength, determined on standard tests. The development of concrete as a struc structur tural al mater material ial,, howeve however, r, has res result ulted ed in spe specia ciall mixture-compositions aimed at the optimization of particular  concrete properties. The determination of the particular properties of defined performance concretes, with the objective of taking best advantage of their characteristics, requires the prescription of related measurement methods. In such a way contemporary standard concrete's for general application and defined performance concrete's can be used in a suitable way for the application being considered (see Figure 6).

FIGURE 6   The MuCEM (M (Musée usée des civi civilisations lisations d dee L'Europe et de lla  a 

Mediteranée) is the first building in which ultra high-performance concrete (UHPC) has been employed in different applications, both as structural member and as sheathing, on a vast scale (source:   https://www.flickr.com — Sébastien Bertrand and Jean-Pierre Jean-PierreDalbéra) Dalbéra)

 

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4.5   |   Design and assessment procedures

To be able to carry out design of new structures and verification of the structural reliability and the remaining service life of existing structures, general models for structural behavior  are necessary. Those models have to be offered with different levels of approximation. The most appropriate level of  approximation for the case being considered depends on the st stag agee of deve develo lopm pmen ent, t, fo forr exam exampl ple, e, pr pred edes esig ign n or fina finall design des ign,, along along with with the comple complexit xity y and con conse seque quence ncess of  intervention. The design and assessment methods should be suitable for new stru structur ctures, es, incl including uding high performa performance nce stru structur ctural al material mate rials, s, existing existing structur structures es built with trad tradition itional al or even outdated structural materials and procedures, existing structur tures es des design igned ed on the basis basis of supers supersede eded d metho methods, ds, and structures in which there is deterioration of their materials. The design and assessment methods should also be valid for  struct structure uress aft after er ret retrof rofitt itting ing,, so that that the rol rolee of advanc advanced ed repair materials and methods should be included. Target verification criteria should be given for all levels of applicati application; on; including including stru structure cturess after after interven intervention tion (see Figuree 7). The design Figur design and assess assessment ment methods methods should should be valid for structural safety (including the effect of dynamic loa loadin ding g and temper temperatu ature re eff effect ects) s) and se servi rvice ceabi abilit lity, y, for  defined periods of time (in relation to the required service life), life ), and taking account account of wider wider sustaina sustainabili bility ty and resilience considerations. Attention is to be given to the importance of good conceptual design, as well as conceptual redesign, desi gn, based on a defined defined minimum level of infor informati mation on about the condition of the structure considered. 4.6   |   Advancements enabled by numerical tools, monitoring, and sensor techniques

The   fib   Model Model Code Code 2020 2020 will will aim aim an ena enabli bling ng use and benefiting from new technologies. For structures with special characte characterist ristics ics (size, (size, comp complica lications tions,, advanced advanced shapes, shapes, unknown boundary conditions) reliable numerical analyses can provide provide valuable valuable informati information on on stru structur ctural al behavior, behavior, safety and remaining service life. It is expected that non linea earr FEM analys analysis is wi will ll be inc increa reasi singly ngly used used in the fut future ure for both:

FIGURE 7   Repair of sub substructure structure of a 

VA0128 overpass on the Ljubljana —Koper  highway, Slovenia, using cathodic protection system at test site of FP6 ARCHES (source: Rob Polder)

 

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  new structures characterized characterized by high structural complexity and/or special details or by use of special materials, and for  •   exis existi ting ng stru struct ctur ures es in th thei eirr orig origin inal al stat statee or afte after  r  intervention. •

There is then the need to define a consistent safety format for such types of analysis calibrated on the current reliability levels. The use of non linear FEM will also require the definition of specific model uncertainties to ensure the reliability level of such calculation tools, calibrated on a set  of specific experimental tests. Testing Test ing and moni monitorin toring g shall shall enable enable to assess assess reli reliable able data on the real conditions and behavior of structures, and may enable reduction of uncertainties in the assessment and prediction of the performance of the structures. In situ load testing and proof loading may be a useful tool for the definition of structural behavior and for the updating of the numerical models describing the structure; specific provisions for  the use of such special types of test on the structure will be given in the Model Code. Monitorin Moni toring g is beco becoming ming a funda fundamenta mentall tool to cont control rol the evolution in time of structural behavior and to allow a  predictive, instead of reactive, policy to be used to control the maintenance process. The developing availability of lowcost microsensors (MEMS) will allow their extensive use in the measurement of local behaviors (crack opening evolution, stress levels) and overall behavior (displacements, rotations, accelerations). The Model Code will give suggestions for the treatment of large data sets (Big Data) produced by monitoring. These processes are expected to involve the use of spe specif cific ic alg algori orithm thmss and by the devel developm opment ent of selfselfdiagnosis procedures. 4.7   |   New issu issues es for con consideration sideration

When working toward a new Model Code for concrete structures, inevitably blind spots show up. Areas are found where expressions based on laboratory testing do not give a sufficiently ciently repr represe esenta ntative tive basis basis for solv solving ing prac practic tical al problem problems. s. Such a mismatch between the results of research and practice, may indicate a clear requirement requirement to develop improved models

 

 

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for structur structural al behavior behavior,, with increas increased ed practic practical al rele relevanc vance. e. Moreover More over new developm developments ents are expe expecte cted d wit with h regard regard to effective monitoring of structures and the management of big sets sets of data, data, result resulting ing in improve improved d maintena maintenance nce program programs. s. There are many aspects of deterioration models which have to be impr improved oved.. Another Another challenge challenge is the use of web websit sites es offering offe ring defineddefined-purp purpose ose cal calcul culati ation on program programss or relevant  relevant  appropriate appropria te data, for the analysis analysis of structures structures under particu particular  lar  conditions. Feedback from users of any updated code, particularly a future-oriented Model Code, can be of tremendous value for the introduction of further improvements. improvements.

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  Adopted Adopted improv improved ed way wayss of wor workin king g inc includ luding ing tar target  get  workshops on specific issues, and so on.

Further discussions will be needed to resolve how radical the approach should be to create a general structural code for  both new and existing concrete structures. In terms of new ways for delivering the  fib Model Code  for concrete structures, the use of con conte tempo mporar rary y (di (digit gital) al) delivery routes is foreseen. This would potentially ease the

 fib   MC2020 MC2020 is envisa envisaged ged as an am ambit bitiou iouss and extrem extremely ely challenging project that would build upon the achievements of  fib  fib  MC 2010 and its treatment of activities for the conservation vation of exi existi sting ng concre concrete te st struc ructur tures. es. The vis vision ion for   fib MC2020, as a single merged general structural code, is to go beyond the point reached by  fib  MC2010, recent ISO codes, such as ISO 16311, and the current Eurocode activities to

task of subsequently maintaining/undertaking further development of the  fib Mod Model el Cod Codee for con concret cretee str struct ucture uress, as well as facilitating improvements in the knowledge dissemination process working in coordination with  fib  COM9:  Disseminatio semin ation n of knowle knowledge. dge.   This could allow allow   fib   to reach a  larger audience, as well as potentially allowing efficient periodic adjustments to be made to the technical content of the  fib Model Code for concrete structures   when when th this is was was appropriate. Although Alth ough the above considerati considerations ons are not exha exhaustiv ustive, e, it is clear that the   fib   MC2020 project will open up new fields fields of end endea eavor vor in struc structur tural al eng engine ineeri ering ng tha thatt should should help help faci facili lita tate te harm harmon oniz izat atio ion n of stru struct ctur ural al desi design gn and and

extend their application to existing structures. It is proposed that MC2020 will take sustainability as a  fundamental requirement, based upon a holistic treatment of  societal needs and impacts, life-cycle cost and environmental impacts. Adopting an integrated life-cycle approach, the requirements for social performance would have defining implications for subs subsidia idiary ry performa performance nce requireme requirements nts crit critica icall to structural design and assessment procedures. These are matters such as human and environmental safety, serviceability, durability, robustness of the structure and the resilience of its functionality, as well as other performance aspects, including aesthetics, adaptability, maintenance, and so on.

assessm assessment ent concepts concepts and proc procedure eduress whic which h curr currentl ently y vary in the diffe differe rent nt regio regions ns and countr countries ies of the world world.. The work on Model Code 2020 is expected to contribute to the future futu re deve developme lopment nt of other other aspe aspects cts of   fib   activities, activities, such as providing material for future   fib  semina  seminars rs and teac teaching hing cours cou rses, es, inc includ luding ing tho those se to be giv given en in dev devel elopi oping ng cou counntries tries.. The work work is als also o lik likely ely to ide identi ntify fy specif specific ic topics topics and resea research rch activ activiti ities es (t (to o be under undertak taken en by oth other ers) s) tha that  t  would benefit owners of concrete structures, as well as the professi prof essionals onals involve involved d in the throu through-l gh-life ife care care and manageme age ment nt of the lar large ge num number ber of existi existing ng con concr crete ete struc struc-tures tures.. La Last, st, but not least, least, the MC2020 MC2020 pro progra gram m of wor work  k  will help maintain and, we trust, enhance the international

It is pro propos posed ed tha that  t   fib   MC2020 MC2020 wil willl follow follow an int inteegrat grated ed li life fe cycl cyclee pers perspe pect ctiv ivee and and serv servic icee life life desi design gn approach appro ach which which promotes promotes a holistic holistic treatme treatment nt of defi defined ned performa perf ormance nce requ requirem irements ents incorpora incorporating ting cons consider ideratio ation n of  structural safety, serviceability, serviceability, durability, and sustainability that link to wider issues such as the through-life managem agemen ent, t, cost cost,, envi enviro ronm nmen enta tall and and soci societ etal al im impa pact ctss of  concrete structures. The process for developing  fib  MC2020 is expected to:

  fib. reputation of  fib.

5   |   CONCLUDING REMARKS

•

  Involve all  fib  commissions and bodies working on relevant vant to topi pics cs for for ex exam ampl ple, e, CO COM3 M3   Existing Existing concre concrete te structures,  as well as engaging with other international

engineering and material science bodies.   Establish a shared vision of specifics of the task —say via various initial workshops. •   Employ a planning, coordinating and drafting body to ide identi ntify fy topic topics/t s/the he desire desired d con conten tents ts for    fib   Model Code 2020.

•

ACKNOWLEDGMENTS

The authors wish to acknowledge the wide range of ideas incorporated into this paper which were received from various sources and in particular for the contributions made by atte attend ndee eess at th thee work worksh shop opss and and T1 T10. 0.1 1 meet meetin ings gs held held between June 2015 and March 2017, and those arising from  the valuable Core Group discussions in Madrid in December  2015. ORCID  Agnieszka  Agnieszk a Bigaj-van Vliet    http://orcid.org/0000-0001-8678-4990

REFERENCES 1.   fib MC2010.   Model Code for Concrete Structures 2010. Fédération Internationale du Béton (fib), Lausanne, Switzerland . Berlin: Wilhelm Ernst & Sohn, 2013.

 

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2.   Walraven JC. Model code 2010 for concrete structures: mastering challenges and encountering new ones.  Struct Concr . 2013;14(1):3–9. 3.   Sakai K, Shibata T, Kasuga A, Nakamura H. Sustainability design of concrete structures.  Struct Concr . 2016;17(6):1115–1124. 4.   Matthews S, Bigaj-van Vliet AJ, Ueda T. Conservation of concrete structures according to fib  Model Code 2010.  Struct Concr . 2013;14(4):362–377. Herrmann n A. A perform performanc ance-b e-base ased d approac approach h for mechan mechanical ical 5.   Dehn F, Herrman concrete conc rete propert properties ies—a roa roadma dmap p toward towardss constit constitutiv utivee cohere coherence nce.. In: Beusha Beushause usen n HD, edi editor. tor.   fib Sympos Symposium ium 2016: 2016: perfor performan mance-b ce-base ased  d  Cap pe approache appr oachess for concrete concrete structures structures — Cape C ape Tow Town/S n/Sout outh h Afri Africa ca. Ca Town,, South Africa: International Town International Federation Federation for Structural Structural Concrete Concrete (fib), 2016; p. 83 –90. ISBN:978-2-88394-121-2 ISBN:978-2-88394-121-2.. 6.   Institution of Structural Engineers.   Appraisal of existing structures. 3rd ed. London: ISE, 2010 [refer to Table 6.1 for indicative usage of cement and concrete products in the UK]. 7.   Neville AM.  Properties of concrete. 4th ed. Essex: Longman, 1995. 8.   Denton S. Advancing the  fib  Model Code for concrete structures. Paper presented at: fib Workshop: Advancing the  f ib  Model Code for concrete structures: need for code provisions for assessment, interventions and management  of existing concrete structures, The Hague, Jun 30; 2015,

AUTHOR'S BIOGRAPHIE BIOGRAPHIES S

Stuart Matthews Building Buil ding Technolog Technology y Group Group,, Build Build-in ing g Rese Resear arch ch Es Esta tabl blis ishm hmen entt Ltd, Ltd, Hertfordshire UK 

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 Joost Walraven Fa Facu cult lty y of Ci Civi vill En Engi gine neer erin ing g and and Geos Geosci cien ence ces, s, Delf Delftt Univ Univer ersi sity ty of  Technology, Delft, The Netherlands  [email protected]  j.c.walrave [email protected]

Giuseppe Mancini Faculty Facu lty of Civi Civill Engineeri Engineering, ng, Politechnico di Torino, Turin, Italy [email protected] 

Gerrie Dieteren Buildings, Infrastructure and Maritime, TNO, The Netherlands Netherlands [email protected]

[email protected] 

Agnieszka Bigaj-van Vliet  Buildings, Infrastructure and Maritime, TNO, The Netherlands Netherlands [email protected]

How to ci How cite te th this is arti articl cle: e:   Matthe Matthews ws S, BigajBigaj-van van Vliet A, Walraven J, Mancini G, Dieteren G.  fib Model Code 2020: Towards a general code for both new and existing concrete structures.   Structural Concrete. 2018; 1–11. https://doi.org/10.1002/suco.201700198 11. https://doi.org/10.1002/suco.201700198