midas civil training_0220-edit-final.pdf

MIDAS e-Learning Courses

Sharing Knowledge, Gaining Experience, Making Difference Organized By MIDASoft, Inc.

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

3


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

4


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

5


Midas Civil graphic user interface

6


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

7


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.

8


Modeling-part 1 Part 1 •

Unit setting

•

Define material and sections

•

Geometry •

Arch

•

Hangers

•

Cross beams

•

Longitudinal girders

•

Structure Alignment

•

Braces

9


Units setting

File  New Project Tools  Unit System

1. Length ft 2. Force  kips 3. Click OK

10


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

11


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

12


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

13


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

14


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

15


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

16


Hangers

Intersect hangers & tie Node/Element  Intersectt 1. Select tie elements 2. Apply

2

1

17


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)

18


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

19


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

20


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

21


Wind brace

Create wind braces Node/Element  Create Elements 1. Material 1: A501 2. Section 4: Braces 3. Create wind braces

22


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


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

24


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

25


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

26


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

27


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

28


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

29


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

30


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

11

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

12

31


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


Run analysis 1: Final Stage

33


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

34


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

35


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

36


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

37


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

38


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.

39


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

40


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.


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

42


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

43


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

44


Construction stage analysis control data


Run analysis 2: Construction Stage

46


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

midas civil training_0220-edit-final.pdf

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