ADVANCED ENGINEERING SCIENCE

Report - Linear and Non-linear Behaviour

Elastic critical lateral torsional buckling and post-buckling non-linear behaviour of steel girders

Objectives:
To demonstrate appropriate understanding, application and limitations of the proposed procedure for design of steel structural members subjected to destabilising effects, in particular lateral torsional buckling.

To establish a procedure using FE to determine the Elastic Buckling Moment Mcr for various support conditions and geometric properties.

To investigate the non-linear behaviour (both geometry and material non-linearity) for elements subjected to lateral torsional buckling

Analysis and Design Requirements
You are required to determine the bending design buckling resistance of a steel bridge girder, Mb,Rd in the bare-steel stage (construction stage). The girder is simply supported for in-plane bending with torsional restraint at both ends. The girder is assumed to carry a vertical udl. The data shown in Tables 1&2 provide the individualised parameters for each student.

Critically discuss and provide a concise correctly referenced summary of the available procedures for determining the Critical Buckling Moment, Mcr , and the ultimate bending resistance capacity of the steel girders referring to published literature and codes of practice. Please use APA referencing system.

Discuss how the value of Mcr is used according to the procedure in BS EN1993 to determine the design buckling moment resistance, Mb,Rd.

Determine, using Finite Elements Method, the Elastic Critical Buckling Moment, Mcr, for the bridge girder given in the Data section below. Clearly present the deformed buckled shape and clearly state the value of the uniformly distributed load (udl) at the point of buckling instability. Verify the value of Mcr using a formula from the published literature.

Carry-out, and critically discuss, the following analyses on the bridge girder in question, using Finite Elements Method.

First Order Elastic Analysis

First Order Plastic Analysis (Material Non-Linearity-MNL)

Second-order Plastic analysis (Geometric and Material Non-linearity, GNL and MNL)

Assume and justify appropriate initial distortion (imperfections). Assume and justify appropriate steel material model. Present clearly the load-deflection behaviour during load increments to clearly establish the bending resistance capacity.

Critically discuss how web stiffeners and bracing systems are used in practice when designing steel girders. Examples of bracing systems are shown in Fig.3.

Learning outcome 1: Critically appraise and formulate engineering problems.

Learning outcome 2: Evaluate solutions for engineering problems by using constitutive relationships and material failure theorems.

Learning outcome 3: Formulate, predict and test behaviour of Structures using a commercial FEM package.

Learning outcome 4: Assess and evaluate the results from the computer analysis.

Attachment:- Advanced_Engineering_Science.rar