rekabentuk jambatan

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 1

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 2

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 3

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 4

FOR INTERNAL USE ONLY

IV.

BUKU PANDUAN REKABENTUK JAMBATAN

ABUTMENT FOR THE WIDENING OF BRIDGE

In recent years the%amount of traffic flows have increased considerably and as a result of this, bridges (normally in rural areas) that were designed during colonial times had to be widened to meet the capacity of the present traffic flow. Basically the widening of bridges can be divided into 2 cases. (i) Widening on one side only It is worthwhile to mention here, that bridge widenings are treated as a separate bridge. thus any soil settlement occuring in the newly constructed extension would not effect the existing bridge.

proportionally. This phenomena arises from the mere fact that under JKR practice HB-vehicle is guided along the centre line. (ii) Widening on both sides The consideration of D.L., W.L., HA-Live load, surcharge pressure and S.T.C. would be exactly the same as mentioned for case i). No HB load will be taken into consideration since it is unlikely that it will move along the extension, provided both the extension width are the same. The steps involved in the designing of abutment for the extension will follow the same lines as that of conventional abutment.. Provision should be given to provide ample space for installation of piles, especially those adjacent to the existing structure as illustrated in fig.3.

The loading imposed on the bridge widening will depend on the type of extension required. (i) Widening on one side only The treatment of dead load, wind load, HA-live load, surcharge pressure and shear, temperature, shrinkage (S.T.C.) will be similar tothat mentioned for onventional abutment. However, full HA-live load will be considered as, acting on the whole width of the poposed widening,.because the two structures are not monolithic. Traction load will be taken as the full traction force if the new centre line within the extension. But if the centre line lies along., the existing bridge, traction force will be half of the above. This is illustrated in 1z 19 In the case of HB-loading where distance 'a' (refer fig.2J is 1.725m or less, then no HB will be taken consideration. on the other hand if distance 'a' happens to be more than 1.725m, HB loading will be divided Cawangan Jalan, Ibu Pejabat JKR, K.L

Page 5

BUKU PANDUAN REKABENTUK JAMBATAN

FOR INTERNAL USE ONLY

(i) Widening on one side only

Cawangan Jalan, Ibu Pejabat JKR, K.L

Page 6

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 7

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 8

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 9

FOR INTERNAL USE ONLY

BUKU PANDUAN REKABENTUK JAMBATAN

REFERENCES 1. Reynolds & Steedman, Reinforcement Concrete Designer's Handbook London, Viewpoint Publications, 9th Edition, 1981. 2. W.L. Scott, W. Glaville & F.G. Thomas, Ex~lainary Handbook on the B.S. Code of Prqctice for reinforced concrete CP114 : 1957 London, Cement & Concrete Association 1965 3. Code of Practice for Foundations London, British Standards Institution, CP 2004 : 1972 4. E. Pennels, Concrete Bridge Designer's Manual London, Viewpoint Publications, 1981 5. Concrete Bridges, D. Beckett Survey University Press. 6. W.H. Mosley & J.H. Bungey, Reinforced Concrete Design. 7. Brian J. Bells, Reinforced Concrete Foundation.

C H A P T E R 8 FOUNDATION FOUNDATION PART I DESIGN OF BRIDGE FOUNDATIONS DESIGN OF BRIDGE FOUNDATIONS 1. Shallow Foundations bridges are seldom founded directly on shallow foundations except if the foundation material is rock or weathered rock. Table I gives the allowable bearing pressure for sound/weathered rock. the bearing capacity in Table 1 may be confirmed or checked by load-bearing tests at site. Cawangan Jalan, Ibu Pejabat JKR, K.L

for shallow foundations, slope stability problems may arise and need be checked. 2. Piled Foundations please refer to the notes on "Design of Pile Foundations" 3. Additional Remark on Piled Foundation 3a. Choice of Pile Type for bridge structure, raketrpiles are often necessary so we must choose piles which can be raked in construction. Driven castin place piles and bored cast-in-situ piles may be ruled out. for normal bridge structure, the number of pile is often not big, it may be cheaper to use precast piles fabricated at some manufacturer's casting yard, e.g. prestressed pretensioned concrete piles. in rural areas, e.g. Felda schemes, site access may be a problem, so avoid piles requiring special heavy equipment. piles in bridge foundations may require some capacity in bending due to lateral loads, etc., hence piles with higher EI preferred, e.g. steel cylinders over steel Hpiles. minimum lengths in pile may be necessary so that erosion due to scouring is taken care of. If steel piles are within scourable depth corrosion provision is necessary. 3b. Lateral Load Capacity of Pile for piles subjected to only lateral loads, the load capacity may be estimated by several methods, e.g. purely elastic phenomena by H.G. Poulos using subgrade reaction of soil, elastic t plastic phenomena by B.B. Broms, or empirlealmethod by L.C. Reese using the experimental P-y curve properties. Nevertheless these methods are not really applicable here because in bridge foundation, vertical loads are much larger than lateral loads. Page 10

FOR INTERNAL USE ONLY

BUKU PANDUAN REKABENTUK JAMBATAN

when the lateral loads are cyclic in nature, the skin friction as well as the subgrade reaction values must be reduced to allow for the gap in between the soil/pile due to continual cyclic movement, e.g. reduction by 25% for soft clay, and 50% for stiff clay or dense granular material. 4. Analysis of Global Pile Group The force method - a system of axial pile loads is calculated which are simply in equilibrium with applied loads Fig. 1). The rivet group method piles are considered vertical and in, equilibrium with the vertical component of the applied load. Then some piles are raked so that the horizontal components of their axial loads balancethe horizontal component of the applied load.(Fig. 2) In some cases, small unbalanced lateral forces may be tolerated since most piles can withstand certain amount of bending in service condition. E.g. Teng W.C. (1976) quotedthat for reinforced concrete piles to 16 inches in diameter, the allowable lateral load may be up to 21 tons in average .good soil conditions. In any case, an allowable lateral load of 0.5 ton is permissible for such piles. The centroid method - in Fig. 3. The frame method - the piles and the pile cap are considered to form a frame or trust. The pile cap is assumed to be rigid but the piles are elastic and assumed to be rigidly supported at certain point of the length. The cap/pile and pile/support connections can be pinned or fixed (say at least 2 feet into the pile cap for fixed cap/pile connection). Some engineers design for the worst conditions of pinned and fixed connections. The point of f ixity at the sup port may be estimated by earth pressure theories.(Fig . 4) other methods using computers such as space frame or more sophisticated plane frame or elastic halfspace. Cawangan Jalan, Ibu Pejabat JKR, K.L

5. Uncertainties of the Analytical Methods The analysis of a pile system with vertical and raker piles, subjected to vertical and horizontal loads, has not been perfected due to many reasons: E.g. the use of soil modulus concept is based on the unrealistic assumption of linear elastic load/deflection behaviour. The elastical theories of soil pressure, on the other hand is based on failure in the ultimate states. In the truss or frame system, the soil is assumed to have no lateral resistance, which may be too severe an assumption. In the simpler force or rivet group or centroid methods, no account is taken of secondary moments due to flexure of the piles. The assumption of uniform distribution of forces of piles in any row is too simplified. More common is that when the bearing strata settle, piles at the end rows support is greater than piles in. the middle of the row. lack of field data since there are little tests done on pile groups subjected to a combination of vertical and lateral loads. comparisons of different methods may indicate surprisingly large differences in the calculated loads acting on the same piles. Judgement and experience are important. 6. Design Good Practice a fan of piles is better than a group with all central piles. vertical and edge piles raked.

Page 11

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 12

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 13

BUKU PANDUAN REKABENTUK JAMBATAN

FOR INTERNAL USE ONLY

Table 1 Allowable bearing capacity of rock

Rock Type

CP 2004 (KN/m2)

NAVFAC

1

hard,sound massive igneous rock, e.g. granite

10,000

80

2

metamorphic rock e.g. schist

3,000

35

3

sedimentary rock e.g.sandstone, mudstone, limestone without cavity

2,000 4,000

20

4

argillaceous rock, e.g. shale

600 1,000

10

5

soft limestone

600

-

6

weathered rock of any kind

-

10

7

compacted gravel, gravelsand mixture

Codes of practice

(1) (2)

Cawangan Jalan, Ibu Pejabat JKR, K.L

600

3-7

British Standards CP 2004 - 1972 U.S. Naval Facilities Engineering Command NAVFAC. DM - 7.2

Page 14

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 15

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 16

FOR INTERNAL USE ONLY

BUKU PANDUAN REKABENTUK JAMBATAN

DESIGN OF PILE FOUNDATION INTRODUCTION Piles are structural members used to transmit the surface loads to firmer soil below. The load transfer may be by friction, g!nd bearing or combination of both. If the load is resisted by skin resistance along the surface of pile, it is called frictional pile. If the pile derive most of its carrying capacity from the resistance of dense stratum of soil or rock, it is called the end bearing pile.

load per pile is 5-10 kN. Bakau piles must be installed below ground water table to ensure its durability. Pressure treated timber piles are usually made of Kempas and they are available in 125mm or 150mm sections. Allowable working load per pile varies from 30 kN to 100 kN. It was instructed by Ketua Pengarah Kerja Raya in 1975 that pressure treated timber piles shall not be used for building more than 2 storeys high. Also only one joint is allowed for the pressure treated timber pile. 2.2.1.2 PRECAST REINFORCED CONCRETE PILES

2. TYPES OF PILES 2.1 CLASSIFICATION OF PILES The British Standard Code of Practice for Foundation (CP 2004) places piles in three categories. They are as follows: (i) Displacement (or large displacement) piles - These include all solid piles, including timber, precast concrete, steel and concrete tubes closed at the lower end by a shoe or plug. (ii) Small displacement piles - These include rolled steel sections, open ended tubes, and screw piles. (iii) Non-displacement piles - These are formed by boring or other methods of excavation; the borehole may be lined with a casing or tube that is either left in place or extracted as the hole is filled. 2.2

COMMON TYPES OF PILES USED IN JKR PROJECTS

2.2.1 DRIVEN DISPLACEMENT PILES 2.2.1.1 TIMBER PILES The common timber piles used in JKR projects are bakau pile and ' pressure treated timber piles. The common type of bakau timber used. are Bakau Minyak and Bakau Kurap. Bakau piles are generally about 100mm in diameter and 5-6m in length. The allowable Cawangan Jalan, Ibu Pejabat JKR, K.L

This is the most commonly used pile type in JKR projects. The pile is designed as compression members and longitudinal steel is provided to withstand bending and tensile stress during handling and driving. The common sizes of reinforced concrete /piles used in JKR Projects varies from 250mm to 400mm square section. The usual design load for these type of pile are in the region of 300 - 600 kN. 2.2.1.3 PRECAST PRESTRESSED CONRCETE PILES Precast prestressed concretes piles are regularly used in JKR projects. Then' principal advantage over ordinary reinforced concrete pile is the higher strength to weight ratio , enabling long slender units to be lifted and driven. The second main advantage is the effect of the prestressing in closing up cracks during handling and driving. This effect, combined with the high quality concrete necessary for economic employment of prestressing, gives the prestressed concrete pile increased durability. The common sizes for the prestressed concrete pile is similar to precast reinforced concrete piles, i.e. 250 - 400mm square section. The usual design load per pile is 300 - 650 kN. 2.2.1.4

STEEL PILES

Steel piles have the advantage of being robust, light to handle and'capable of Page 17

FOR INTERNAL USE ONLY

BUKU PANDUAN REKABENTUK JAMBATAN

being driven hard to deep penetration to reach a bearing stratum. They can carry high compressive loads when they are seated in a hard stratum. They can be designed as small displacement piles, which is advantageous in situations when ground heave and lateral displacement must be avoided. They can be readily cut down and extended where the level of the bearing stratum varies. H-section and pipe pile are the common steel pile used in this country. The design load for steel H--pile is about 300 - 1800 kN where as for steel pipe pile it is in the region 300 - 3000 kN. 2.2.2. DRIVEN CAST-IN-SITU DISPLACEMENT PILES Driven cast-in-situ piles are installed by driving to the desired penetration a -steel tube with its end closed. A reinforcing cage is next placed in the tube which is then filled with concrete. The tube is withdrawn while placi g the concrete./This system of piling is usually/ patented basing on using different types of shoes of driving technique or casing withdrawal procedure. The system used in this country is'the patented Franki Pile. The design load per pile is in the range of 650 - 1500 kN. Driven and cast-in-situ piles have the principal advantage of being readily adjustable in length to suit the desired depth of penetration. 2.2.3 NON-DISPLACEMENT PILES (BORED CAST-IN-SITU PILES) Bored cast-in-situ piles are installed by first removing the soil by a drilling process, and then constructing the pile by placingconcrete in the drilled hole. The simplest form of construction consists, of drilling an unlined hole and filling it with concrete. In water. bearing,soils, and soft clay, casing is needed to support the sides of the borehole. The casing is withdrawn after placing concrete. In stiff to hard clays and weak rocks, an enlarged base can be formed to increase the end bearing resistance. Design load for bored cast-in-situ pile varies from 400 - 6500 kN.

Cawangan Jalan, Ibu Pejabat JKR, K.L

Micropiles are classified as small diameter (less than 200mm) bored cast-in-situ piles. The special feature of the micropile is its strength, resulting from the placing of a reinforcement and its seating in a hole of sufficient diameter which may be bored in whatever direction is best suited to the requirements of the projects. The equipments used'in-the installation of micropiles are much smaller than those used in bored piles and so it is very convenient to move and install these-equipments. In areas where the ground consist of hard weatherd rock they require special diamond-tipped drills and for large diameter boreholes the process of drilling will be quite difficult. Moreover only few contractors can supply these drills. Whereas for micropiles the drilling process can be, easily done due to the small diameter. The micropiles are good foundation in fractured rocks where the cracks/fractures can be grouted at the same time of grouting the micropiles. For existing structures where the foundation is found to fail these micropiles Ican be used because they do not require large equipments or space to work on and so the other parts of the structure will not be affected. The working loads of micropiles as specified by the soils lab are between 400KN to 800KN but some contractors claim that they can reach up till 1500 KN for 250 mm diameter micropiles. 3.

SELECTION OF PILE TYPE

The select ion.of pile type should be made studying the ground conditions, properties/limitations and cost of various types of pile, and the effect of installation upon existing structures. The maximum load for different sizes and types of piles as used by JKR are as given in the table 1.

Page 18

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 19

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 20

FOR INTERNAL USE ONLY

BUKU PANDUAN REKABENTUK JAMBATAN

(i)to provide for natural variations in the strength and compressibility of soil (ii) to provide for uncertainties in the calculations (iii) to ensure that the total and differential settlements are within tolerable limits. Large number-of loading tests in a variety of soil types have shown that for small to medium (up to 1.2m) diameter piles, the settlement at working load will not exceed 3/8", if the factor of safety is not lower than 2.5. 4.4

PILE BEARING ON ROCK

If a pile can be driven to strong intact bedrock, the safe working load on the pile is governed by -the permissible working stress on-the material of pile, provided pile is not driven through soft clay of fluid consistency. 4.5

PILE BEARING CAPACITY BASED ON STATIC PENETRATION TEST

The bearing capacity of pile can also be calculated using the Dutch-cone penetrometer results. The ultimate base resistance Qb of pile is Qb = Ckd x Ab ' Where Ckd = unit cone resistance Ab = area of base of pile The value of unit cone resistance used should be the average cone resistance taken over a shaft length of three times the pile diameter above the toe and one pile diameter below the toe. . The ultimate frictional resistance Qf.is given by Qf = Fc As Where Fc = unit local friction".measured using the friction sleeve As = area of shaft of pile

Cawangan Jalan, Ibu Pejabat JKR, K.L

Page 21

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 1

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 22

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 23

FOR INTERNAL USE ONLY

5.3

BUKU PANDUAN REKABENTUK JAMBATAN

PILE GROUP TERMINATING IN ROCK

There is no risk of block failure of pile group if the piles have been properly seated in the rock formation. There is no problem of excessive settlement of a well constructed pile group foundation on rock. 5.4

NEGATIVE SKIN FRICTION IN PILE GROUP

Broms have suggested the negative skin friction of pile group be calculated based onFig. 10. If the spacing of the piles is'large, each pile will carry a load resulting from the maximum skin friction Ca (calculated in section 4.6) down to the neutral point. When the spacing of the piles in the group is small, the load increase is as indicated in Fig. 10. The pile group will carry a total load which corresponds to the shear resistance of the soil on the perimeter area of the pile group plus the weight of the fill above the pile group i.e. 2 Cu L (B1 +B2) + B1 B2 qfit

Cawangan Jalan, Ibu Pejabat JKR, K.L

Page 24

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 25

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 26

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 27

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 28

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 29

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 30

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 31

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 32

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 33

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 34

FOR INTERNAL USE ONLY

BUKU PANDUAN REKABENTUK JAMBATAN

into the bearing stratum. Ab = Area of base of Pile, 6. Evaluate the factor of safety of the pile. It is arguable as to what is a suitable factor of safety, and how it should be evaluated. *Tomlinson has quoted that if a factor of safety of 2.5 is used on the total ultimate pile resistance (Q u + Qb), then the settlement at working load is unlikely to exceed 10mm (0.4)in, i.e. Allowable load = ultimate pile resistance, Q u ---------------------------------2.5 However, for large diameter piles exceeding 600 mm. (2ft.), the problem of settlement become more severe. This is because the settlement required to mobilize the end bearing resistance is much more than that required to mobilize skin friction (Skin friction can be mobilised with a downward movement of only about 0.3 to 1% of the pile diameter, while to mobilize the full base resistance requires a downward movement of about 10 to 20% of the base diameter). *Tomlinson, M.J. - Pile design and construction practice, viewpoint 1977. Thus the concept of partial factors of safety is more appliable in the case of large diameter piles. The method suggested by Burland, Butlre and Dunican is to use do allowable load which is the lower of the two given below: (a) Allowable load = z (Qs + Qb) (b) Allowable load = Q+ Qs b. 7. Having determined the allowable load on the pile, check this against the required working load. If the allowable load is less than the required working load, try a longer length of pile and go back to step 3. If the allowable load is more than the required working load a check must be made against the structural capacity of the pile. If, the allowable structural capacity of the pile is exceeded, then. the actual Cawangan Jalan, Ibu Pejabat JKR, K.L

allowable load must be the allowable structural capacity of the piles as determined from structural calculations based on the strengths of the materials making up the pile. Guidelines for the design of: Driven piles in cohesionless soils (Sands) (Cu=O) (Based on borehole results) The bearing capacity of piles in sand is mainly contributed by end bearing,-frictional resistance giving only a relatively small contribution.. The classic formula is: Qu = Nq Pd Ab + 1/2 Ks Pd tan SAs ---------------------------------Qb Qs Where Qu = Ultimate total pile resistance. P d = effective overburden pressure at pile base level. Nq = bearing capacity factor. Ab = base area of pile. Ks = coefficient of earth pressure which depends on relative density of soil, volume displacement of pile, material of pile, shape of pile. S = angle of friction between pile and soil. As = surface area of pile in contact with soil. The steps in the design of driven piles in cohesionless soils are as follows: 1. Examine the soil profile and decide of a bearing stratum of cohesionless soil. This bearing stratum must be at least 6 Diameters thick and should not be underlain by a softer, compressible material. If there is a compressible material below it, then it is advisible to penetrate the soft material to a lower bearing stratum, unless the sand overlying the soft materialis very dense and very thick (unusual). 2. Decide on a trial depth of pile, i.e., decide where the base of the pile is to be founded. The pile must be driven at least 5 Diameters into the bearing stratum, but there is not much point in driving the pile more than 20 Page 35

FOR INTERNAL USE ONLY

BUKU PANDUAN REKABENTUK JAMBATAN

Diameters into the bearing stratum. The limiting value of 20 Diameters is because it is thought that a peak value of Qb is reached at 20 Diameters penetration. The causes of this peak value is thought to be due to the arching of the soil above the pile toe with the tendency to form horizontal cracks in the soil, and due to pulverization of the soil beneath the pile toe under the impact of the hammer blows. 3.

Determine the end bearing resistance from Qb = Nq PdAb

(Qb must not be taken as greater than 10.7 MN/M2 or 100 tons/ft'). Different' authors give different values of Nq . Tomlinson recommends that given by Berezantsev, et al (fig 4.14, Tomlinson* ). Before Nq can be determined, the value of dia. has to be known. This can be obtained from the relationship between SPT and 91 given by Peck, Hanson & Thorbuin(fig 4.13, Tomlinson*). For SPT done on fine sands or silts below the water table , it is safer to apply a correction N' = 15 +1/2 (N-15) for values of N above 15. It must not be forgotten that pd is the effective overburden pressure at pile base level. (*Tomlinson, M.J. - Pile Design & Construction Practice, Viewpoint 1977). 4. Calculate the ultimate skin friction, Qs, from Qs= 1/2 Ks Pd tan & As Value of & and Ks are given in Table 4 (Note that there are other methods) of calculating the skin friction of piles in cohesionless soils, e.g. Nordlunds method) 5. Determine the allowable load on the pile. see steps 6 and 7 of the notes for driven piles in cohesive soils.

Cawangan Jalan, Ibu Pejabat JKR, K.L

Page 36

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 37

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 38

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 39

FOR INTERNAL USE ONLY

Cawangan Jalan, Ibu Pejabat JKR, K.L

BUKU PANDUAN REKABENTUK JAMBATAN

Page 40

FOR INTERNAL USE ONLY

BUKU PANDUAN REKABENTUK JAMBATAN

PRINCIPAL REFERENCES 1. CP 2004, "Foundations" British Standards Institutions, London, 1972. 2. Design Manual 7.2, "Foundations and Earth Structures." Department of the Navy, Nagal Facilities Engineering Command, Alexandria, (USA) 1982. 3. "Precast Piling Practice" by B.B. Broms, Thomas Telford Ltd., London, 1981. 4. "Pile Design and Construction Practice," M.J. Tomlinson, Viewpoint Publications, London, 1977. 5. "Bridge Foundations and Substructures," E.C. Hambly, Building Research Establishment Report, Department of the Environment, London, 1979 6. Course notes from ".Geotechnical Engineering Course" Universiti Malaya, Kuala Lumpur, March - April, 1982.

Cawangan Jalan, Ibu Pejabat JKR, K.L

Page 41