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Network Tied Arch Modeling, Analysis & Design
Bridging Your Innovations to Realities
midas Civil Bridging Your Innovations to Realities
Contents The following will be contents of this training 1.
Introduction
2.
Modeling
- Summary of In-depth Discussion Session
- Unit Setting
- midas Civil GUI
- Materials & Sections
-Project Information
- Geometry: Arch, Hanger Arrangements, Tie, Wind Braces - Boundaries & Loads
3.
Analysis and Design - Moving Load - Final Stage Analysis - Unknown Load Factors - Hanger Force Tuning - Set up for Construction Stage
- Construction Stage Analysis - Time History Analysis - Hanger Loss
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midas Civil Bridging Your Innovations to Realities
Introduction •
Summary of in-depth discussion session: •
Analysis and design considerations
•
Construction and final stage analysis
•
midas Civil’s functions:
•
Unknown load factor
•
Cable load tuning
•
Moving load tracer
•
midas Civil Graphic User Interface (GUI)
•
Project information
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midas Civil Bridging Your Innovations to Realities
Summary of in-depth discussion Design of Network Tied Arch Moving Load Tracer
1. Final Stage •
Calculate cable forces & cable force tuning
•
Correct geometry
•
Critical live load
•
Extraordinary Loads (accidental hanger loss)
Hanger Force Adjustment •
Optimization problem influence matrix •
Cable Tuning
•
Time History Analysis
2. Construction Stage •
Nonlinear behavior of cables
•
Temporary supports situation
Unknown Load Factor
Lack of Fit force •
Hanger forces at different construction stages
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midas Civil Bridging Your Innovations to Realities
Midas Civil graphic user interface
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midas Civil Bridging Your Innovations to Realities
Project information Bridge Type: Network Tied Arch • Bridge Length: 300 ft • Arch Height : 60 ft • Width : 30 ft
• Number of Lanes : 2 60 ft
300 ft
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midas Civil Bridging Your Innovations to Realities
Project information Network Tied Arch bridge need to be studied in two different stages, Construction stage and Final stage, so we need two model files for each stage.
We start with Final stage model and apply all the ultimate static loads to the structure and run a linear static analysis. The main purpose of this stage is to find optimized pretensioning forces in each hanger for the best performance of the bridge.
The second part is investigation of bridge’s behavior during erection. In this stage the hanger forces obtained from the first model will be used as initial pretensioning force of hangers during construction stages, and responses of the bridge will be monitored. The model used in this stage contains 42 construction stages starting from tie and arch erection with help of temporary supports and ending by installing hangers and remove the temporary supports.
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Modeling-part 1 Part 1 •
Unit setting
•
Define material and sections
•
Geometry •
Arch
•
Hangers
•
Cross beams
•
Longitudinal girders
•
Structure Alignment
•
Braces
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midas Civil Bridging Your Innovations to Realities
Units setting
File New Project Tools Unit System
1. Length ft 2. Force kips 3. Click OK
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midas Civil Bridging Your Innovations to Realities
Materials
Properties Material Properties
1. Click Add
3
1 2
4 5
2. Type of Design Steel 3. Name A501 4. Standard ASTM09(S) 5. DB A501 6. Click OK Similarly Define Grade C5000 Material in Type of Design as Concrete
6
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midas Civil Bridging Your Innovations to Realities
Sections Properties Section Properties
1 2
1. Click Add 2. Type I section 3. Name Arch
3
4
4. Select User Type 5. Enter Parameters as Shown 6. Click OK Similarly Define Sections: W24X250, W10X22, S24X121and cable section with diameter .16feet
5
Properties Thickness Define Thickness of .5 feet
6
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midas Civil Bridging Your Innovations to Realities
Geometry modeling
Create Node Node/Element Create Nodes 1. Enter the following coordinates: (0,0,0), (300, 0, 0), (150, 0, 60) (-75, 0 ,-300) 4 1
Create Element
2
Node/Element Create Elements 1. Material 1: A501 2. Section 2: Tie
3. Click on Nodal Connectivity box to turn green
3
4. Select nodes 1 and 2 by clicking
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midas Civil Bridging Your Innovations to Realities
Arch
Create Arch Node/Element Create Line Element on Curve
1
1. Select Arc by 3 points 2. Material 1: A501 3. Section 1: Arch
2
4. Number: 16 5. Select corresponding nodes from model view
3
as following P1: Node 1 P2: Node 3
4
P3: Node 2 5
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Hanger arrangement
Create Hangers 1
Node/Element Create Elements 1. Element Type: Tension Only/Hook/Cable 2. Material 1: A501 3. Section 5: cable 4. Click on Nodal Connectivity box to turn green 5. Connect node 4 to all nodes on the Arch (5 to
2
5
18) 6. Select all elements and node below the Tie and
3
delete them
6
4
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midas Civil Bridging Your Innovations to Realities
Hangers
Mirror the hangers frame Node/Element Elements Mirror 1. Select all hangers 2. Mode: copy
2 3
3. Reflection: y-z plane, x=150 ft
4. Apply
4
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Hangers
Intersect hangers & tie Node/Element Intersectt 1. Select tie elements 2. Apply
2
1
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midas Civil Bridging Your Innovations to Realities
Structure alignment
Rotate Structure Node/Element Elements Rotate
2
1. Select entire structure 2. Mode: move
3
3. Angle of Rotation: -10 4. Axis of Rotation: last option (2 points) 5. Select nodes 1 and 2 respectively or enter coordinates: 1st point: (0, 0, 0)
10˚ 4 5
2nd point: (300, 0, 0)
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Arch
Mirror the network frame Node/Element Elements Rotate
1. Select entire structure 2. Mode: copy
2
3. Reflection: z-x plane, y=15 ft 4. Apply
3
4
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midas Civil Bridging Your Innovations to Realities
Cross beams
Node/Element Extrude 1. Select Nodes 1, 2, 21, 24, 26, 28, 30, 36, 39 2. Material 1. A501 3. Section 3: Tie 4. Dx,dy,dz 0, 5, 0
2 3
5. Number of times 6
6. Click -> Apply It will create one more node
4
5
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Longitudinal girders
Create Longitudinal girders Node/Element Create Elements 1. Material 1: A501 2. Section 3: Girder 3. Create 5 longitudinal girders by connecting corresponding nodes of cross beams at two ends
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midas Civil Bridging Your Innovations to Realities
Wind brace
Create wind braces Node/Element Create Elements 1. Material 1: A501 2. Section 4: Braces 3. Create wind braces
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midas Civil Bridging Your Innovations to Realities
Modeling-part 2 (Final Stage) Part 2: this model will be used for Final stage analysis •
•
Boundary conditions •
Groups for construction stages (structure, boundary and load groups)
•
Abutments
Loads •
Static load cases
•
Self weight
•
Superimposed dead load
•
Pretensioning force of hangers
•
Moving load
midas Civil Bridging Your Innovations to Realities
Groups for construction staging Group Tab ( Tree Menu) 1. Define the Groups for - Structure: Deck Stage 1 to 4, Arch Stage 1 to 5, Hanger 1 to 30, Temp Restrain 1 to 4, Lack of Fit (all hangers), cross beams - Boundary: End Supports, Temp Supports 1 to 4 - Load Group: Self Weight , SDL, Pretension 1 to 30
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Abutments Boundary Define Supports 1. Select Nodes at the left and the
right end of the bridge 2. Boundary Group Name End Supports 3. Select Dall
2 1
4. Click Apply
3
4
1
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Static load cases Load Static Loads Static Load Cases 1. Name Self Weight 2. Type Dead Load 3. Click Add Similarly Define SDL with Type Dead Load and Pretension 1 to 30 with type Prestress (PS)
1
3
2
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midas Civil Bridging Your Innovations to Realities
Self weight Load Static Loads Self Weight 1. Load Case Name Self Weight 2. Load Group Name Self Weight 3. Z -1 4. Click Add 1 2
3
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midas Civil Bridging Your Innovations to Realities
Superimposed dead load
1 2
4 3
Load Static Loads Element 1. Load Case Name SDL 2. Load Group Name SDL 3. w -70 lb/in 4. Select all longitudinal girders (tie) 5. Click Apply
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Pretensioning Load
Hanger 5 1 Hanger 2 2 Hanger 1
3 5
4
Load Temp./Prestress Pretension Loads 1. Load Case Name Prestress 1 2. Load Group Name Prestress 1 3. Prestress Load: 1 lb 4. Select 1st hangers from left (group: Hanger 1) 5. Click Apply 6. Repeat the process for all hanger groups
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midas Civil Bridging Your Innovations to Realities
Moving Load
Load Moving load 1. Select AASHTO-LRFD 2. Click Traffic Line Lanes
3. Add 4. Name: Lane 1 5. Eccentricity: -7.5 ft 6. Wheel Spacing: 6 ft 7. Vehicular load distribution: select cross beam group 8. Select by 2 points 9. Select nodes 1 and 2 10. Apply 11. Repeat for Lane 2 with eccentricity of -22.5
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midas Civil Bridging Your Innovations to Realities
Moving Load Load> Moving Load Analysis Data> Moving Load case.
5
5. Enter a Load case name: MVL 6. Check or modify Multiple Presence Factor.
3
7.Select loading effect for sub load case as Independent .
6
8. Add Sub-Load case. 9. Select one of the vehicles.. 10. Scale factor as 1, and min. number of loaded lane as 1 and max. as 2. 11. Select lanes L1 and L2.
12. Click OK.
7
13. Similarly create load case for HL-93 Tandem Vehicle.
9
8
10
Load> Moving Load Analysis Data> Vehicles.
1. Click Add Standard 2. Click on Vehicle load type
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3. Select HL-93 TRK as first vehicle load type., DLA = 33%,Click Apply 4. Select HL-93 TDM as second vehicle load type. Click OK
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midas Civil Bridging Your Innovations to Realities
Analysis Moving Load •
Moving load tracer find critical live load configuration
•
Convert to static load
Final Stage Analysis •
Unknown Load factors
•
Hanger force tuning
Construction Stage Analysis •
Geometry nonlinearity
•
Lack of Fit force
Time History Analysis •
Hanger loss
midas Civil Bridging Your Innovations to Realities
Run analysis 1: Final Stage
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midas Civil Bridging Your Innovations to Realities
Results: Moving Load Tracer Results Moving Load Moving Load Tracer Beam Force/Moment 1. Moving load case: Min MLC1 2. Element: 81 3. Apply: the vehicle arrangement that causes maximum negative bending moment will be shown 4. Click Write Min/max Load to file to save this load arrangement as a static load
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midas Civil Bridging Your Innovations to Realities
Load combination
Results Load Combination 1. Create a load combination which
have all load cases (SW, SDL, Pretensions 1~30) with factor 1. 2. Name: LCB 3. Select Self Weight, Factor: 1 4. Repeat for all load cases
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midas Civil Bridging Your Innovations to Realities
Unknown Load Factor The static analysis is performed on final stage model file. Initially a unit pretension force is applied on all hangers, in this stage, after static analysis, we are going to use Unknown Load Factor function to find required pretensioned load in each hanger for certain constrains.
Results Bridge Cable Control Unknown Load Factor 1. Add New 2. Name: Hanger forces 3. Load Combination: Mid Span 4. Add Constraints 5. Name: Deck 131 6. Displacement 7. Node ID: 131 8. Component: Dz
9. Select Inequality 10. Upper and lower bound: 0.75 & -0.75 11.Repeat the process for Nodes 132 to 137
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Unknown Load Factor
1. Load Comb: LCB 2. Square 3. Both 4. Check all Pretension load cases as Unknown 5. Select all Constraints 6. Click get Unknown Load Factors
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midas Civil Bridging Your Innovations to Realities
Hanger forces Factors are calculated for each hanger. This factor is the required pretensioning force to satisfy previously defined constraints. To generate the corresponding load combination: 1. Click Make Load Combination 2. Name: Hanger forces 3. Ok 4. Influence Matrix could be extracted by selecting Influence Matrix.
5. Ok
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midas Civil Bridging Your Innovations to Realities
Hanger forces The load factors, which are required pretensioning forces to be applied to each hanger was calculated and a new load combination is created and the results could be checked under this load combination.
Now the effect of change in pretensioning level of each hanger could be investigated by using Cable Tuning function. The effect of such change on structure response could be monitors as well.
The pretensioning loads obtained at this step, will be used for construction stages analysis.
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midas Civil Bridging Your Innovations to Realities
Hanger force tuning Results Bridge Cable Control Cable Force Tuning 1. Load Combination: Hanger force 2. Name: Hanger forces 3. Click to generate new results 4. Name: Deck moment 5. Group: Deck stage 4 6. Type: Beam force, MY 7. x-Axix: +DX, Element 8. Add 9. Close 10. By changing in level of pretensioning of each hanger, bending moment changes
11. Save load combination as a new combination with all the changes
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midas Civil Bridging Your Innovations to Realities
New set up for construction stages (modeling-part 3) this model will be used for Construction stage analysis •
Boundary conditions Temporary supports
•
Construction Stages set up Define stages
CS analysis control data •
Loads: Update pretensioning force of hangers (obtained from Final Stage Analysis)
In this stage, use the same model just add 42 construction stages, temporary supports (used for erection) and apply pretensioning forces obtained from the previous part.
midas Civil Bridging Your Innovations to Realities
Temporary supports
Boundary Define Supports 1. Select Nodes at the 1st cross
beams from the left and support 2. Boundary Group Name Temp Supports1
1
2
3. Select Dz 4. Click Apply 1
Similarly define supports for nodes at other cross beams by names Temp supports 2 and 3 as the
3
group 4
1
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midas Civil Bridging Your Innovations to Realities
Update pretensioning forces
Unit pretensioning forces of hanger (which defined in the first model) should be updated and replaced by factored obtained previously from Unknown Load Factors function
1. Right click on Pretensioning Load and select Tables 2. Update all prestressing by corresponding force (factors) 3. Data could be arranged in Excel and then copied to the table
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midas Civil Bridging Your Innovations to Realities
Define stages
Load Construction Stage 1. Generate 2. Name: Construction Stage 3. Suffix: 1 to 42 4. Ok 5. Change the names to: Deck 1 ~ 4 Arch 1 ~ 5 Hanger 1 ~ 30 Remove Falsework 1 ~ 3
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midas Civil Bridging Your Innovations to Realities
Construction stage analysis control data
midas Civil Bridging Your Innovations to Realities
Run analysis 2: Construction Stage
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midas Civil Bridging Your Innovations to Realities
Results: Lack of Fit Force Results Results Table Construction Stage Lack of Fit Force Truss
Thank You
Pouya Banibayat, PhD
Sharing Knowledge, Gaining Experience, Making Difference
[email protected] Organized By MIDASoft, Inc.
646-852-9289
