A069 STUDENT STEEL BRIDGE COMPETITION 2011

2011 STUDENT STEEL BRIDGE COMPETITION STRUCTURAL ANALYSIS, DESIGN, AND DRAWING PRODUCTION USING BENTLEY PRODUCTS... AISC/ASCE STUDENT STEEL BRIDGE COMPETITION – 2011 ANALYSIS, DESIGN A

2011 STUDENT STEEL BRIDGE COMPETITION

STRUCTURAL ANALYSIS, DESIGN, AND DRAWING PRODUCTION USING BENTLEY

PRODUCTS

AISC/ASCE STUDENT STEEL BRIDGE

COMPETITION – 2011

ANALYSIS, DESIGN AND DOCUMENTATION OF STEEL BRIDGES

USING STAAD.Pro V8i AND STRUCTURAL MODELER INTEGRATION

By

RAVINDRA OZARKER, P.ENG

APPLICATION ENGINEER STRUCTURAL MODELER GROUP

Table of Contents

1.0 Introduction ……… ……… 5

2.0 Creating the Bridge Geometry/Structural Analysis ……… ………… 8

3.0 Step-by-Step Tutorial ……… ……… 21

Exercise 1: Overall Bridge Geometry……… 21

Exercise 2: Creating the Leg Structure ……….… 30

Exercise 3: Modifying the Deck Geometry ……… 40

Exercise 4: Creating Member Offsets ………51

Exercise 5: Physical Member Formation ……… 61

Exercise 6: Truss Specification Creation and Assignment ……… 63

Exercise 7: Support Creation and Assignment ……… 66

Exercise 8: Property Creation and Assignment ……….67

Exercise 9: Formation of Cantilever Section……… 74

Exercise 10: Creating Load Cases & Items ……… 83

Exercise 11: Performing Analysis ……….91

Exercise 12: Understanding the Results ………92

Exercise 13: Design of the Structure using AISC 360-05 ……… 102

4.0 STAAD.Pro and Structural Modeler Integration ……… 105

5.0 Help, Questions, Comments ……….118

Appendices

A: Creating Bridge Geometry Using STAAD.Pro V8i Grid System ……… 120

B: Creating Bridge Geometry Using STAAD.Pro V8i dxf Import ……… 126

C: STAAD.Pro Input Command File ……… 134

D: Specifying Proper Slenderness Lengths in STAAD.Pro ……… ……… …146

E: Dataset Installation ……… … 154

1.0 Introduction

The Student Steel Bridge Competition is sponsored by the American Institute of Steel Construction

(AISC), American Society of Civil Engineers (ASCE) and cosponsored by the American Iron and Steel

Institute (AISI), Bentley Systems, Inc., Canadian Institute of Steel Construction (CISC), James F Lincoln

Arc Welding Foundation, National Steel Bridge Alliance (NSBA), Nelson Stud Welding, Nucor

Corporation, and Steel Structures Education Foundation (SSEF)

Students design and erect a steel bridge by themselves but may seek advice from faculty and student

organization advisers Civil Engineering students are challenged to an inter-collegiate competition that

includes design, fabrication, and construction of a scaled steel bridge Participating students gain

practical experience in structural design, fabrication processes, construction planning, organization,

project management, and teamwork

In the industry, commercial structural analysis and design software integrated within a BIM (Building

Information Modeling) or BrIM (Bridge Information Modeling) environment are used extensively to

complete projects on time and at the same time lets engineers maintain accuracy and come up with very

efficient design alternatives The correct combination of software tools can make the bridge design,

fabrication and construction task very easy

STAAD.Pro is the professional’s choice for steel, concrete, timber, aluminum and cold-formed steel

structures, culverts, petrochemical plants, tunnels, bridges, piles and much more It is a general purpose

structural analysis and design tool

Structural Modeler is an advanced, yet intuitive and easy-to-use building information modeling (BIM)

application that empowers structural engineers and designers to create structural system models and

related engineering drawings (i.e documentation)

STAAD.Pro and Structural Modeler are integrated STAAD.Pro models can be imported into Structural

Modeler and Structural Modeler models can be exported out to STAAD.Pro

The purpose of this document is to help students analyze and design their bridge models using Bentley’s

STAAD.Pro software and produce engineering layout drawings using Structural Modeler This document

does not teach how to compare advantages of various alternatives that are allowed in this competition

Designers must consider carefully the comparative advantages of various alternatives For example, a

truss bridge may be stiffer than a girder bridge but slower to construct Successful teams analyze and

compare alternative designs prior to fabrication

Following are some statements from the Student Steel Bridge Competition 2011 Rules manual

This Year’s Problem Statement :

A new road in a state park will facilitate travel across the park and improve access to remote areas A

bridge will be constructed over a scenic river and also will carry utilities to a new welcome center and

The bridge with the lowest construction cost (Cc) will win in the construction economy category

Construction cost is computed as

Cc = Total time (minutes) x Number of builders (including barges) x $50,000 per builder-minute

+ $30,000 for each temporary pier in the staging yard

Total time is defined in 7.2.3 and includes penalties The number of builders includes all members and

associates of the competing organization who are within the construction site or physically assist the team

at any time during timed construction or repair

Overall Performance

The overall performance rating of a bridge is the sum of construction cost and structural cost (Cc + Cs)

The bridge achieving the lowest value of this total wins the overall competition

From the above statements it is clear that a bridge that is light and stiff (i.e structurally efficient) may not

necessarily be an overall winner Designers need to keep other criteria such as constructability and cost

(i.e construction economy) in mind

This document and software packages discussed here will help students analyze and understand their

structures better to achieve structural efficiency The documentation that will be produced can be used to

discuss/plan construction economy

2.0 Creating the Bridge Geometry/Structural Analysis

STAAD.Pro can make your bridge design and analysis task easier The bridge geometry in STAAD.Pro

can be constructed in many ways:

1 STAAD.Pro user interface

(a) Bridge Geometry Discussed In This Tutorial

(b) Property Assignment

(c) Lateral Load Test

(d) Vertical Load Test – Step 1

(e) Vertical Load Test – Step 2

Figure 1: Bridge Geometry and Loading Process

Note: If custom cross sections are used for the bridge members, the custom shapes can be modeled as

General Sections You may have to use STAAD.SectionWizard Alternatively, a General Section can

be also created in STAAD.Pro V8i using the instructions on the following link:

ftp://ftp2.bentley.com/dist/collateral/Web/Building/STAADPro/Modeling_Custom Shapes in

STAAD_PRO.pdf

The loads on the bridge will be placed based upon the roll of first dice The following table shows the

possible values of L and locations where the displacements will be measured

Following are all possible values of L and LC based on the roll of the two dice

Table 1: Bridge Loading

Weight of the structure Self weight of the structure

Lateral Load Self weight of the structure

Distributed Load as shown below:

0.075 kip/(2 beams * 3ft deck) = 0.0125 k/ft load on each member

0.075 kip point Load as shown below

Notes:

(1) L is defined in Section 8 of the document entitled Student Steel Bridge Competition - 2011 Rules

3.0 Step-by-Step Tutorial

Exercise 1: Overall Bridge Geometry

1 Launch STAAD.Pro by clicking on the Start->All Programs->STAAD.Pro V8i->STAAD.Pro icon

The STAAD.Pro V8i introduction screen will appear as shown in Figure 2

Note: Make sure that US Design Codes is checked and has a green light besides it The US

Design Codes is not checked, you will need to check this box and close the STAAD.Pro interface

and re-open it again

Figure 2: STAAD.Pro Introduction Screen

2 Click on File->Configure The Configure Program dialog box will appear Make sure that the

Base Unit is set to English

Note: If you will be constructing your bridge model in the metric unit system, make sure that you

set the base unit system to Metric

Figure 3: Base Unit System Setup

3 Click on the File->New menu command The New dialog box will appear

4 Provide the model options as shown in Figure 4

Figure 4: The New Dialog box

5 Click on the Next button The Where do you want to go Today? Dialog box will appear as

shown in Figure 5

6 Click on the Finish button

7 The STAAD.Pro V8i user interface will appear as shown in Figure 6

Figure 5: The Where do you want to go Today? dialog box

Figure 6: STAAD.Pro User Interface

8 You could create the bridge geometry using the grid options shown in Figure 6 Appendix A of

this document illustrates the procedure of creating a simple bridge geometry using the grid

system You could also create a bridge geometry using MicroStation XM and export that drawing

as a dxf Appendix B discusses how this can be achieved In this tutorial, the Structure Wizard

will be used to create the bridge geometry

9 Click on the Geometry->Run Structure Wizard menu command The Structure Wizard user

interface will appear as shown in Figure 7

Figure 7: Structure Wizard User Interface

10 Double click on the Pratt Truss icon on the left The Select Parameters dialog box will appear

as shown in Figure 8

Note: In this dialog box, you can adjust the bay-to-bay spacing by simply clicking on the … icon

Make sure that the summation of the bay-spacing is equal to total length and width that you have

specified respectively

Figure 8: Structure Wizard User Interface

11 Input the parameters in the Select Parameters dialog box as illustrated in Figure 8

12 Press the Apply button The structural geometry will appear as shown in Figure 9

Figure 9: Bridge Structure Geometry in Structure Wizard

13 To transfer the structure to STAAD.Pro, select the File->Merge Model With STAAD.Pro Model

menu command Structure Wizard interface will close and a conformation dialog box will appear

Figure 10: Confirmation dialog box

14 Click Yes for the conformation dialog box The Paste Prototype Model dialog box will appear

15 Click on the Ok button The bridge geometry will be created in STAAD.Pro as shown in Figure

11

Note: The Y Axis should be the axis of gravity in your STAAD.Pro models

Figure 11: Bridge geometry in STAAD.Pro interface

16 The bridge geometry seen in Figure 11 has to be mirrored in the XZ-plane

17 Select the Beams Cursor from the left hand side

Figure 12: Beams Cursor

18 Select all the beams in the graphics window Ctrl + A will select all the beams in the model

19 Click on Geometry->Mirror command The Mirror dialog box will appear as shown in Figure 13

Figure 13: The Mirror dialog box

20 Input the mirror parameters as shown in Figure 13

21 Click the OK button The structure will be mirrored about the X-Z plane as shown in Figure 14

Figure 14: Bridge structure is mirrored about the X-Z plane

Note:

Basic 3D Navigation Tools: Use the arrow keys on the keyboard to rotate structure, the middle

mouse roller button to zoom in and out If you press the roller button and hold it down, you will be

able to pan You may also use the icons in the icon bar

22 Select the node points as shown in Figure 15 using the nodes cursor

Figure 15: Node points selected

23 Select the Geometry->Translational Repeat menu command

Figure 17: Translational repeat command selected

25 The 3D Repeat dialog box will appear as shown in Figure 17 Input the mirror parameters as

shown in Figure 17

26 Click the Ok button The legs of the bridge structure will appear as shown in Figure 18

Figure 18: Legs of the bridge are created

Exercise 2: Creating the Leg Structure

1 Select the leg members and right click with the mouse and select the Insert Node option

Figure 1: Legs of the bridge are created

2 Select the leg members and right click with the mouse and select the Insert Node option

Figure 2: Legs of the bridge are created

3 Click the Ok button The legs of the bridge structure will be subdivided to create the lattice leg

attachment points

Figure 3: Legs of the bridge are created

4 Select the node point on the bottom left hand side corner

Figure 4: Legs of the bridge are created

5 Select the node point on the bottom left hand side corner

6 Right click on the screen and select the copy command This will copy the highlighted node to

the memory

Figure 5: Legs of the bridge are created

7 Right click on the screen and select the Paste command The Paste with Move dialog box will

appear

Figure 7: Legs of the bridge are created

8 Input the parameters as illustrated in Figure 7 and Press the Ok button You will note a new node

point at the lower left hand side of the structure

Figure 8: Legs of the bridge are created

9 Select the Geometry->Add Beam->Add beam from Point to Point menu command

Figure 9: Legs of the bridge are created

10 Connect the nodes with a new beam element as shown in Figure 10

11 Delete all the leg members except the member that was created in the above step and the small

lattice leg attachment points

Figure 10: Legs of the bridge are created

12 Divide the beam into three equally parts Right click on the beam and select the Insert Node

command

13 Input the information in the Insert Nodes dialog box as shown in Figure 11 2 is entered in the n=

input box

Figure 11: Insert nodes dialog box

14 Click the Ok button

15 Select the new leg members as shown in Figure 12

Figure 12: The beam members are selected

16 Select the Geometry->Circular Repeat menu command

17 The 3D Circular dialog box will appear Input the data in the 3D Circular dialog box as shown in

Figure 13

Figure 13: 3D Circular dialog box

18 Click on the node icon as shown in Figure 13 Select the node point as shown in Figure 14

Figure 14: Node point is clicked

19 Press the Ok button The leg members will be created as shown in Figure 15

20 Select the lattice leg member as shown in Figure 15

21 Right click on select the Copy command

Figure 16: Copy command is selected

22 Right click on select the Paste Beams command The Paste with Move dialog box will appear

Figure 17: Paste Beams command is selected

23 Press the Reference Pt button The Specify Reference Point dialog box will appear

Figure 18: Reference Pt button is pressed

Figure 19: Specify Reference Point dialog box

24 Press the Ok button and click on the lower node of the lattice leg attachment points to create the

rest of the leg members as shown in Figure 20

25 Press the Ok button and click on the lower node of the lattice leg attachment points to create the

rest of the leg members as shown in Figure 20

Exercise 3: Modifying the Deck Geometry

1 Select the members as shown in Figure 1 Press the delete key on your keyboard to delete these

members

Figure 1: Members are being deleted

2 Draw a member as shown in Figure 2

Figure 2: New Member is created

3 Select all members in the model by pressing the CTRL+A key on the keyboard