Behavior of Hot Rolled Asymmetric Steel I-Beams: Concept to Construction
Abstract
Steel composite floor systems have been commonly used in commercial and residential floor systems. As the push to reduce building heights and increase building construction speed, concrete floor systems with a shallow depth to span ratio have surged ahead of steel composite floor systems. To make steel more competitive in shallow floor systems, multiple unique asymmetric built-up sections have been produced. These built-up sections are labor-intensive and require long lead times to produce. To make steel more competitive in residential floor systems, a hot-roll asymmetric steel I-beam (termed A-shape) was devised.
The overarching goal of this research was to create new knowledge toward the behavior of A-shapes throughout their life, which includes manufacturing, construction, and operation. The research presented herein is divided into five phases. Phase 1 was thermal-mechanical finite element modeling. The modeling approach used nonlinear steel properties and was experimentally validated. The purpose of the modeling was to capture the residual stresses due to the manufacturing cooling process. A parametric study was executed and the controlling flange width-to-thickness ratios were identified for A-shapes. The modeling was also used to study global deformations due to the cooling process, which was found to be manageable for realistic A-shape geometry.
Phase 2 was the development and production of proof-of-concept (POC) beams. The top flange of W-sections was reduced, and the beams were reheated to simulate the cooling of future hot-rolled asymmetric beams. The POC beams were used for further validation of the simulated global deformations and provided specimens for a full-scale experiment. Phase 2 also incorporated expert feedback from steel mills, which provided guidelines for A-shape dimensions.
Phase 3 was the experimental testing of a full-scale floor system incorporating the POC beams. During all stages of construction and actuator loading, A-shape beam strains and deflections were monitored. The data collected was used to understand the structural behavior of A-shapes as well as validate the theoretical calculations to be used in the next phase.
Phase 4 was a comprehensive analytical study to understand the controlling limits for A-shapes during construction and in-service. The study that was devised evaluated four unique loading scenarios, under 18 limit states, to fully understand the behavior of A-shapes. Phase 5 utilized the understanding of A-shape manufacturing, construction, and in-service behavior to develop recommended A-shape dimensions.
Citation
Stoddard, Eric Alan (2022). Behavior of Hot Rolled Asymmetric Steel I-Beams: Concept to Construction. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /197261.