2011 STUDENT STEEL BRIDGE COMPETITION STRUCTURAL ANALYSIS, DESIGN, AND DRAWING PRODUCTION USING BENTLEY PRODUCTS tailieuxdcd@gmail.com 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 September 1, 2010 tailieuxdcd@gmail.com Table of Contents 1.0 Introduction …………………………………………………………………………… ……… 2.0 Creating the Bridge Geometry/Structural Analysis ………………………………… ………… 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 tailieuxdcd@gmail.com 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 tailieuxdcd@gmail.com 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) tailieuxdcd@gmail.com 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 camp ground The Park Commission has requested design/build proposals for the new bridge Construction Speed The bridge with the lowest total time will win in this category Construction Economy 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 Lightness The bridge with the least total weight will win in the lightness category Stiffness The bridge with the lowest aggregate deflection will win in the stiffness category Structural Efficiency The bridge with the lowest structural cost (Cs) will win in the structural efficiency category Structural cost is computed as Cs = Total weight (pounds) x $4000 per pound + [Aggregate deflection (inches)]1.5 x $1,200,000 tailieuxdcd@gmail.com 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 tailieuxdcd@gmail.com 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: STAAD.Pro user interface Structure Wizard Using a DXF import (importing a dxf MicroStation or AutoCAD drawing) Structural Modeler ProSteel 3D In this case part of the bridge geometry will be created using Structure Wizard The bridge geometry is shown in Figure tailieuxdcd@gmail.com (a) Bridge Geometry Discussed In This Tutorial tailieuxdcd@gmail.com (b) Property Assignment (c) Lateral Load Test 10 tailieuxdcd@gmail.com TO UNI GY -0.15 TO UNI GY -0.0042 18 21 *** LOAD LOADTYPE None TITLE L=0 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.15 TO UNI GY -0.0058 18 21 *** LOAD LOADTYPE None TITLE L=3 VLT PRELOAD SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.104166 TO UNI GY -0.0042 18 21 *** LOAD LOADTYPE None TITLE L=3 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.15 TO UNI GY -0.0042 18 21 *** LOAD LOADTYPE None TITLE L=3 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.15 TO UNI GY -0.0058 18 21 *** LOAD LOADTYPE None TITLE L=6 VLT PRELOAD SELFWEIGHT Y -1 PMEMBER LOAD 142 tailieuxdcd@gmail.com TO UNI GY -0.104166 TO UNI GY -0.0042 18 21 *** LOAD LOADTYPE None TITLE L=6 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.15 TO UNI GY -0.0042 18 21 *** LOAD LOADTYPE None TITLE L=6 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.15 TO UNI GY -0.0058 18 21 *** LOAD 10 LOADTYPE None TITLE L=7 VLT PRELOAD SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.104166 10 TO UNI GY -0.0042 18 21 *** LOAD 11 LOADTYPE None TITLE L=7 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.15 10 TO UNI GY -0.0042 18 21 *** LOAD 12 LOADTYPE None TITLE L=7 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD 143 tailieuxdcd@gmail.com TO UNI GY -0.15 10 TO UNI GY -0.0058 18 21 *** LOAD 13 LOADTYPE None TITLE L=9 VLT PRELOAD SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.104166 10 TO UNI GY -0.0042 18 21 *** LOAD 14 LOADTYPE None TITLE L=9 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.15 12 TO UNI GY -0.0042 18 21 *** LOAD 15 LOADTYPE None TITLE L=9 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.15 12 TO UNI GY -0.0058 18 21 *** LOAD 16 LOADTYPE None TITLE L=12 VLT PRELOAD SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.104166 12 15 TO UNI GY -0.0042 18 21 *** LOAD 17 LOADTYPE None TITLE L=12 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD 144 tailieuxdcd@gmail.com TO UNI GY -0.15 12 15 TO UNI GY -0.0042 18 21 *** LOAD 18 LOADTYPE None TITLE L=12 VLT STEP SELFWEIGHT Y -1 PMEMBER LOAD TO UNI GY -0.15 12 15 TO UNI GY -0.0058 18 21 *** LOAD 19 LOADTYPE None TITLE WEIGHT SELFWEIGHT Y -1 *** LOAD 20 LOADTYPE None TITLE LATERAL LOAD SELFWEIGHT Y -1 PMEMBER LOAD UNI GY -0.0125 6.5 9.5 CON GZ 0.075 PERFORM ANALYSIS PRINT ALL PARAMETER CODE AISC UNIFIED FYLD 7200 ALL METHOD LRFD CHECK CODE ALL FINISH 145 tailieuxdcd@gmail.com APPENDIX D SPECIFYING PROPER SLENDERNESS LENGTHS IN STAAD.PRO 146 tailieuxdcd@gmail.com 1.0 Introduction STAAD.Pro is a general purpose structural analysis and design tool The structural engineer may also first create the steel frame models in STAAD.Pro and design then design the steel frames using the appropriate loading and codes The purpose of this document is to demonstrate the use of the LY and LZ design parameters in STAAD.Pro 147 tailieuxdcd@gmail.com 2.0 Slenderness Lengths Following figure shows four identical members attached to a steel frame One of the bays has secondary beams (i.e the rear bay) The remaining two bays have secondary beams but the engineer did not model those intermediate beams in this model (e.g bay at the front) Figure 1: Steel tubes (Identical Members) attached to a steel frame There is no force directly applied to the identical members The structure is symmetric and loads are symmetric also One would expect either all the four members to pass or all four to fail Figure 2: Code Check results 148 tailieuxdcd@gmail.com The engineer performed a code check using the AISC 360-05 code on the entire frame and obtained the results shown in Figure Note that two of the four identical members at the front fail with a design ratio of 1.14 The two identical members at the rear end of the structure have very low unity ratios The beams at the front failed in STAAD.Pro due to slenderness limitations and effective length or Section E2 of the AISC 360-05 code Let us look at the results for the front identical member * 40 ST TUB20203 (AISC SECTIONS) FAIL Clause E2 1.143 0.22 C 0.00 0.01 14.14 | -| | SECTION CLASS: CB: 0.000 | ACTUAL RATIO: 228.59 ALLOWABLE RATIO: 200.00 | | SLENDERNESS CHECK: | SECTION CAPACITIES: (UNIT - KIP FEET) | | AX.TENS: 0.00E+00 COMPRESS:0.00E+00 TORSION: 0.00E+00 | | BEND Z: 0.00E+00 BEND Y: 0.00E+00 SHEAR Z: 0.00E+00 SHEAR Y: 0.00E+00 | | -| | SECTION PROPERTIES: (UNIT - FEET) | | AXX: 0.01 AYY: 0.01 AZZ: 0.01 RZZ: 0.06 RYY: 0.06 | | SZZ: 0.00 SYY: 0.00 | | -| | PARAMETER: (UNIT - KIP FEET) | | KL/R-Z: 228.59 KL/R-Y: 228.59 UNL: 4.7 CB: 0.00 FYLD: 5184.00 | | FU: 8352.00 NET SECTION FACTOR: 1.00 SHEAR LAG FACTOR: 1.00 STP: | | DFF: 0.00 dff: 23.00 | | -| | CRITICAL LOADS FOR EACH CLAUSE CHECK (UNITS KIP -FEET) | | CLAUSE RATIO LOAD FX VY VZ MZ MY | | Cl.D2 0.000 0.00E+00 | | Cl.E 0.000 0.00E+00 | | Cl.F-Major 0.000 0.00E+00 | | Cl.F-Minor 0.000 0.00E+00 | | Cl.H1/H2 0.000 0.00 0.00E+00 0.00E+00 | | Cl.G-Major 0.000 0.00E+00 | | Cl.G-Minor 0.000 0.00E+00 | | Cl.H3 0.000 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 | | -| ERROR : CALCULATED SLENDERNESS RATIO EXCEEDS ALLOWABLE LIMIT The beams at the front should have passed but failed due to slenderness because the KL/r of the beam exceeds the allowable slenderness value of 200 The slenderness length (i.e Lx in KLx/rx or Lz in KLz/rz) value is the member length in STAAD.Pro by default Engineers have to check if the member length is the slenderness length based on how the structure has been modeled In this case, the two identical members at the rear end of the structure have a LZ and LY of 4.71 ft Using the information presented in Figure below, the slenderness length may be 4.71 for LY but LZ should be 14.14 ft This is because there is no restraint along the Local Y axis 149 tailieuxdcd@gmail.com Figure 3: Lz or Slenderness length about local z axis (out of the plane of the slope) In the case of the two identical beams at the front, you will note that we have not modeled the secondary beams In this case, the LY (Slenderness length about the local Y axis as shown in Figure 5) should be set to 4.17 ft 150 tailieuxdcd@gmail.com Figure 4: Slenderness lengths can be specified in STAAD.Pro as Design Parameters Figure 5: Ly or Slenderness length about local y axis (in the plane of the slope) 151 tailieuxdcd@gmail.com After implementing these changes, you will note that the four identical beams have identical design ratios of 1.14 Figure 6: Updated Code Check results The user may use STAAD.Pro’s Interactive Steel Designer to estimate the values of LX, LY, and LZ, however engineering judgment is required in this case also Figure shows how the LY and LZ calculated by the Interactive Steel Designer may not be correct The LY for physical members M3 and M4 should be 4.71 ft 152 tailieuxdcd@gmail.com Figure 7: Formation of Physical Members in STAAD.Pro 153 tailieuxdcd@gmail.com APPENDIX E DATASET INSTALLATION 154 tailieuxdcd@gmail.com Dataset Installation: Attached is the “Structural Analysis, Design, And Drawing Production” document prepared for participants of this year’s AISC 2011 Student Steel Bridge Competition This year dataset zip file “STUDENT_STEEL_BRIDGE_COMPETITION_2011_DATASETS_BENTLEY.zip” is also distributed with the manual The manual has thirteen step-by-step exercises Unzip the contents of the zip file to a location on your computer (e.g c:\training) You could use winzip to see/unzip the contents or you could simply right click on the file and click on explore Let us assume that you right click on the file and select Explore Windows Explorer will appear as shown below Copy the folder inside the zip file to a safe location on your machine The STUDENT_STEEL_BRIDGE_COMPETITION_2011_DATASETS_BENTLEY folder contains three sub-folders i ii Microstation – Contains a dxf file for Appendix A STAAD.Pro – Contains nine STAAD.Pro models My Bridge_1.std which contains results of following Ex to in the manual This file can be used for Ex My Bridge_2.std which contains results of following Ex to in the manual This file can be used for Ex My Bridge_3.std which contains results of following Ex to in the manual This file can be used for Ex 10 My Bridge_4.std which contains results of following Ex to 10 in the manual This file can be used for Ex 11 My Bridge_5.std which contains results of following Ex to 11 in the manual This file can be used for Ex 12 155 tailieuxdcd@gmail.com My Bridge_6.std which contains results of following Ex to 12 in the manual This file can be used for Ex 13 My Bridge_7.std which contains results of following Ex to 13 in the manual This file can be used for Section 4.0 This file has been provided so that the user can experiment with STAAD/Structural Model Integration My Bridge_8.std which contains results of following Ex to 13 in the manual This file can be used for Section 4.0 This file has been provided modified for STAAD/Structural Model Integration The properties were renamed for proper mapping and loadings were removed iii My Bridge_9.std which contains results of following Ex to 13 in the manual This file can be used for Section 4.0 This file has been provided modified for STAAD/Structural Model Integration The properties were renamed for proper mapping and loadings were removed This file is just a backup of My Bridge_8.std file The My Bridge_8.std may get modified after the first import (i.e additional groups will be created for design history reasons) If you would like to get to the unmodified version of My Bridge_8.std you may open My Bridge_9.std Structural Modeler bridge_mapping_file.txt – Mapping file used in Section 4.0 Bridge_Model.dgn – Structural Modeler file that was created using the STAAD.Pro file in Section 4.0 StructuralShapesTemplate-2.xls – The MS Excel file modified in Section 4.0 and is used to define custom shapes in Structural Modeler 156 tailieuxdcd@gmail.com