ORCID Identifier(s)

0000-0003-2162-7956

Graduation Semester and Year

2020

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil Engineering

First Advisor

Shih-Ho Chao

Abstract

The Staggered Truss Framing (STF) system is a type of steel structural system used in mid- to high-rise buildings. It was initially developed in the 1960s in order to create a steel framing system that has low floor-to-floor height (9 to 10 ft.) and wide column-free space (60 to 80 ft.). This system consists of a series of story-high trusses spanning the total width between two rows of exterior columns and arranged in a staggered pattern on adjacent column lines. Due to the staggered layout, lateral seismic force transfer in the STF system is also in a staggered manner from the top of the structure; therefore, the lower floor’s diaphragm and its connections are carrying increasingly larger load due to the accumulative inertia forces all the way from the top level of the building. Nevertheless, STF’s seismic behavior is nearly unknown and extensive analytical and three-dimensional experimental studies and collapse simulations are needed in order to understand its seismic behavior. The main objectives of this study are to investigate the cyclic behavior of the connection between precast hollow-core slab diaphragm to steel truss in the STF system, to present a design procedure for the STF system, and to evaluate the seismic performance of the proposed modified STF by nonlinear time-history (NTH) analyses. Large-scale experiments were tested under cyclic loading protocols. The results showed that the prestressed precast hollow-core slab and its connection to the steel chord of the STF system has insufficient strengths to resist high shear forces. On the other hand, Finite Element Analyses (FEA) showed that some interior connections are under the effect of double shear. Nonlinear analyses show that STF system with the modified configurations including multi-panel Vierendeel panels in the middle of trusses with addition of vertical members in the non-truss levels can effectively improve the ductility and seismic behavior of steel trusses. It also has clearly defined yield mechanism and structural fuses compared with the conventional STF system. Furthermore, the STF system no longer primarily depends on staggered manner via the diaphragms to transfer the lateral forces, as in the conventional STF system. Nonlinear analyses also showed that using the horizontal trusses as a diaphragm can effectively transfer the seismic forces along the longitudinal direction.

Keywords

STF, Steel, Seismic

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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