GSA – Getting it Right

2 What's New GSA 8.7? New Steel Design Codes New RC slab design codes New Footfall Analysis Codes — BS 6841:1987; BS ; User defined frequency weighting curve. Non-linear Shell Elements Assemblies and Assembly Results Modal and Seismic Analysis Improvements New Mesh Generation Engine — quicker processing, producing smaller and better conditioned meshes. Curved Members Faster processing — including faster grid load expansion, faster response spectrum analysis, faster post processing, and faster RC Slab calculations. New GsRevit Functionality — improved coordination, improved section mapping and Revit 2014 compatibility. Patterned Load — a set of tools for the analysis of generalised patterned floor loading.

Examples When things go wrong

Sleipner ATacoma Narrows I-5 Skagit River BridgeSavar Building, Banglaseh

5 Sleipner A Offshore Platform

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What can go wrong? And how can you fix it?

9 Did you really mean to do that?

10 The key thing to remember is… GSA MODEL RUBBISH OUTRUBBISH IN

11 What is the matrix?

12 What is the matrix?

13 Please release me…

14 Please release me… Restraints All nodes are free to move, though controlled by the attached elements, unless they are restrained in some way Typical use – support points Rigid Constraints Rigid Constraints / Links / Joints Means for adding infinite stiffness between nodes without problems in the stiffness matrix Typical use – floor diaphragms Releases All elements are fully fixed to the nodes and hence other elements, unless they are released in some way Typical use – beam connections

15 Units If you don’t get what you expect: check your units

16 Materials

17 What a difference that shear makes

18 What a difference that shear makes Giving a property a zero stiffness will lead to instability in the matrix Except zero shear stiffness, as this switches of shear deflection…

19 Location, Location, Location

20 Location, Location, Location

21 FEA is not CAD

22 FEA is not CAD The main purpose of CAD is to represent the physical requirements of the structure and communicate it to others The main purpose of FEA is to mathematically predict the physical behaviour of the structure and to facilitate the design of the elements Do you really need the offsets…?

23 Loads of problems

24 Loads of problems

25 Loads of problems

26 Stability

27 Stability

28 Stability

29 I know that the answer is around here somewhere

30 I know that the answer is around here somewhere

31 I know that the answer is around here somewhere

32 Size matters

33 Size matters

34 Another fine mesh…

35 Another fine mesh…

36 Another fine mesh…

37 Tricks and Tools

38 Tricks and Tools Look at the deflected shape If you are doing a static analysis Run a dynamic one as well If you are doing a dynamic analysis Run a static one as well If something is just not right Run a Model Stability Diagnostic analysis

39 Many a slip…

40 Lessons from the floor

GSA – Getting it Right