Abstract

Metal buildings with roof truss diaphragms and tension-only rod bracing are a common structural system for single story industrial and commercial buildings. Despite the widespread use of metal building diaphragms in modern construction, there is limited knowledge on their strength and ductility under seismic loads. In this study, finite element models of diaphragm subassemblies and a full-size diaphragm were created to determine the strength and ductility of metal building diaphragms with tension-only rod bracing using hillside washer rod connections. Finite element models of two-tier diaphragm specimens that had been previously tested in the laboratory were created. Girders and purlins were modeled using elastic beam-column elements. Tension rods were modeled using elastic-perfectly plastic elements with a failure strain that was calibrated to match the subassembly test data. The tension rod anchorage connection was modeled using an elastic perfectly plastic gap material in series with an elastic material. The diaphragm subassembly model was subjected to monotonic and cyclic loading and the hysteresis results were used to determine the static subassembly strength and ductility. A finite element model of a full-size eight-tier roof truss diaphragm in a high-seismic location was created. The full-size model was subjected to monotonic and cyclic loading to determine static diaphragm strength and ductility. A parametric study was used to determine the effect of rod, purlin, girder, and friction parameters. The results of the parametric study indicate that the rod yield stress, rod size, rod connection stiffness and the friction force had a significant affect on the load-deformation response of the diaphragm, while other parameters had a negligible effect. From the subassembly model, predicted overstrength and ductility factors were found to range from 1.33 to 1.44 and 2.00 to 2.92 respectively. The calculated ductility factors were found to match the predicted ductility values. However, the overstrength factors varied from the predicted values. The full-size model was subjected to a ground motion record that was scaled to match the design response spectrum for the location. The results show that the dynamic diaphragm ductility capacity for this building was adequate to withstand the diaphragm ductility demand under the Maximum Considered Earthquake level ground motions for the ground motion examined.

Degree

MS

College and Department

Ira A. Fulton College of Engineering; Civil and Environmental Engineering

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2024-04-18

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd13604

Keywords

roof truss diaphragms, tension-only rod bracing, finite element models, monotonic, cyclic loading, force reduction factor

Language

english

Download

Included in

Engineering Commons

Share

COinS