Finite Element Analysis Workflow for Heat Straightening of Impact-damaged Steel Bridges PDF Download
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Author: Norman Fong Publisher: ISBN: Category : Languages : en Pages : 92
Book Description
Impacts between over-height vehicles and steel bridges are common throughout North America and the resulting bridge damage is unpredictable and sudden. Heat straightening is an alternative to replacing steel members and mechanical straightening for repairs. In many cases, bridges remediated using heat straightening require fewer disruptions to traffic and lower repair costs compared to repairs replacing steel members. Heat straightening limitations and practices have been developed with American steel grades and climates in mind. Often heat straightening is described as an art as much as a science; this repair method has relied on experienced practitioners using heat straightening patterns designed to cause rotations or shortening in members. Heat straightening of impact-damaged steel bridges can be modelled with finite element analysis (FEA). Heat straightening is a thermo-mechanical process. Existing studies modelling heat straightening with FEA do not fully explain the modelling techniques and material parameters used. A workflow defining steps and material parameters can be used to facilitate modelling of impact and heat straightening on bridges. This study proposes a workflow using FEA to model the heat straightening of impact-damaged steel bridges. The proposed workflow will be used to study heat straightening of CSA 350W steel - a commonly used Canadian steel grade. The workflow is developed by investigating modelling techniques for impact and heat straightening separately. The developed finite element models include material parameters accounting for work hardening, thermal effects and strain-rate sensitivity of steel. The presented research demonstrates that the proposed workflow is viable for modelling impact and heat straightening of steel bridges. Although this study involved the application of the developed modelling techniques for a hypothetical bridge, the exercise has provided valuable insight into methods of expediting heat straightening repair and the modelling process. For instance, it has provided insight into the following: the introduction of jacking forces without causing mechanical straightening, the removal of plastically deformed stiffeners to reduce deformations, and the treatment of residual stresses from heat straightening.
Author: Norman Fong Publisher: ISBN: Category : Languages : en Pages : 92
Book Description
Impacts between over-height vehicles and steel bridges are common throughout North America and the resulting bridge damage is unpredictable and sudden. Heat straightening is an alternative to replacing steel members and mechanical straightening for repairs. In many cases, bridges remediated using heat straightening require fewer disruptions to traffic and lower repair costs compared to repairs replacing steel members. Heat straightening limitations and practices have been developed with American steel grades and climates in mind. Often heat straightening is described as an art as much as a science; this repair method has relied on experienced practitioners using heat straightening patterns designed to cause rotations or shortening in members. Heat straightening of impact-damaged steel bridges can be modelled with finite element analysis (FEA). Heat straightening is a thermo-mechanical process. Existing studies modelling heat straightening with FEA do not fully explain the modelling techniques and material parameters used. A workflow defining steps and material parameters can be used to facilitate modelling of impact and heat straightening on bridges. This study proposes a workflow using FEA to model the heat straightening of impact-damaged steel bridges. The proposed workflow will be used to study heat straightening of CSA 350W steel - a commonly used Canadian steel grade. The workflow is developed by investigating modelling techniques for impact and heat straightening separately. The developed finite element models include material parameters accounting for work hardening, thermal effects and strain-rate sensitivity of steel. The presented research demonstrates that the proposed workflow is viable for modelling impact and heat straightening of steel bridges. Although this study involved the application of the developed modelling techniques for a hypothetical bridge, the exercise has provided valuable insight into methods of expediting heat straightening repair and the modelling process. For instance, it has provided insight into the following: the introduction of jacking forces without causing mechanical straightening, the removal of plastically deformed stiffeners to reduce deformations, and the treatment of residual stresses from heat straightening.
Author: Robert J. Connor Publisher: Transportation Research Board ISBN: 0309099374 Category : Transportation Languages : en Pages : 140
Book Description
TRB¿s National Cooperative Highway Research Program (NCHRP) Report 604: Heat-Straightening Repair of Damaged Steel Bridge Girders: Fatigue and Fracture Performance explores limits, based on fatigue and fracture performance, on the number of damage and repair cycles to which damaged steel bridge girders may be subjected using the heat-straightening procedure.
Author: Matthew Lackowski Publisher: Purdue University Press ISBN: 9781622601134 Category : Transportation Languages : en Pages : 78
Book Description
Significant research has been conducted on the development of: (1) heat straightening repair techniques and their field implementation, (2) guidelines and recommendations for heat straightening repair, (3) empirical procedures for estimating plastic rotations achieved during heat straightening, (4) empirical procedures for predicting residual stresses caused by heat straightening, and (5) the effects of heat straightening on the structural properties of repaired bridges. Currently, there is a need for additional research on: (a) the fatigue performance of heat straightened beams, (b) the effects of single and multiple heat straightening on the fracture toughness and microstructure of steel beams, (c) the development of guidelines for evaluating and replacing steel beams subjected to single or multiple damage-repairs, and (d) investigating the effects of realistic heat straightening with imperfections on the properties and serviceability of steel beam bridges. The literature review of existing heat treatments indicates that heat straightening with maximum temperature limited to 1200 F is relatively similar to the process annealing heat treatment. Heat straightening with maximum temperature limited to 1400oF is similar to the normalizing annealing heat treatment. Both these heat treatments repair plastically deformed microstructure by the phenomenon known as recovery and recrystallization. Normalizing annealing is more efficient and faster than process annealing in repairing the plastically deformed microstructure by recrystallization. Heat treatment and repair of the material microstructure is incidental to the heat straightening repair process. The heat straightened beam can be further heat treated to complete the repair of the material microstructure (recrystallization etc.). The practical and economic feasibility of additional heat treatment using electrically powered and controlled radiant heaters was evaluated and found to be reasonable.
Author: Amit Hariom Varma Publisher: ISBN: Category : Iron and steel bridges Languages : en Pages :
Book Description
The effects of multiple damage-heat straightening repair events on the structural properties and fracture toughness of A36, A588, and A7 bridge steels were investigated experimentally. The damage and repair parameters included in the project are: (i) the damage strain, (ii) the restraining stress, (iii) the number of damage-repair cycles, and (iv) the maximum heating temperature. Extensive laboratory-scale and large-scale tests were conducted to evaluate the effects of these parameters on the structural properties including: (a) elastic modulus, (b) yield stress, (c) ultimate stress, (d) % elongation, (e) surface hardness, (f) fracture toughness, and (g) microstructure. Ninety-one laboratory-scale specimens, and six large-scale beam specimens made from A36, A588, and A7 steel were tested.