Effect of Temperature Increase on Lateral Response of Axially Restrained Beams Subjected to Concentrated Loads

Author

Kyle Frick, Southern Illinois University CarbondaleFollow

Date of Award

8-1-2016

Degree Name

Master of Science

Department

Civil Engineering

First Advisor

Kassimali, Aslam

Abstract

The lateral response of axially restrained beams with various end conditions is presented herein using nonlinear analysis. The beams were studied for three end conditions, with two lengths per end condition and two magnitudes of point loads per length. The method of analysis was performed using geometrically non-linear analysis. Material nonlinear analysis was not considered. This method of analysis, which is based on Eulerian (corotational) formulation and includes thermal effects, was published by Kassimali and Garcilazo (2010). Graphical results are shown for the response of the beams. The results are also compared to published values given in the AISC manual. The following conclusions were shown from this study: 1) When comparing the amplification factors (both deflection and bending moment) found in this study to the amplification factors given in the AISC manual, the data shows similar values in the pre-buckling region. However, once the temperature is raised high enough and the beam enters the post-buckling region, significant difference in the amplification factors can be seen. The beams in this study showed that the amplification factors do not increase greatly during post-buckling. The values given in the AISC manual on the other hand show an indefinite increase in amplification factor once the buckling stage is reached. It is thought that this decrease in amplification factors in post-buckling is due to the increased strength in the beams from catenary forces that are developed. 2) When comparing similar beams (same end conditions and same lateral loads), the length of the beam will play a role in the lateral response to thermal loading. It was consistently shown in all end support conditions that the shorter beams developed higher amplification factors compared to the longer beams. This difference was not substantial in the pre-buckling stage, but once the beam approached the critical temperature and into the post-buckling range, the difference in amplification factors became significant. 3) Along the same lines, comparing beams with the same end conditions and same length, the magnitude of the lateral load also played a role in the lateral response of the beams. The beams with the lighter lateral loads would develop higher amplification factors than the heavier loaded beams. As with the length, the lateral loads didn’t have much difference until the beams would approach the critical temperature. However, after that point, the difference of the amplification factors would become quite large.