Award Date

December 2023

Degree Type

Thesis

Degree Name

Master of Science in Engineering (MSE)

Department

Civil and Environmental Engineering and Construction

First Committee Member

Ying Tian

Second Committee Member

Nader Ghafoori

Third Committee Member

David James

Fourth Committee Member

Zhiyong Wang

Number of Pages

87

Abstract

Catastrophic progressive collapses of reinforced concrete (RC) frame buildings can be triggered by column failure. In such a scenario, the beams supported by the failed column shall be able to form an alternative load path guarding the building against collapse. The compressive arch action passively generated after losing a column has been identified as an effective load-resisting mechanism for axially restrained RC frame beams. However, the beams need to continuously carry the redistributed gravity loads sustaining in the structural system. Past research predominantly focused on the short-time collapse resistance of RC beams and little is known about their time-dependent response under high sustained loads. Therefore, sustained loading tests were performed on three RC beam-column subassemblies to study their long-term collapse resistance provided by the compressive arch action after losing a supporting column. The major test variables included loading age (between 50 and 267 days) and beam transverse reinforcement ratio (0.327%, 0.436%, and 0.655%). The specimens were tested at high sustained loads of 80% and 90% of the nominal short-term loading capacity under compressive arch action. The performance of a specimen tested in an earlier study was used as a basis to identify the effects of loading age and transverse reinforcement ratio on the time-dependent response of RC frame beams under high sustained loads. The experimental results indicated that younger loading age and lower transverse reinforcement ratio cause greater second order effects associated with creep-induced deformation, thereby decreasing the sustained loading capacity of beams. Additionally, Poisson’s ratio of concrete cover is a suitable indicator for the impending failure of RC frame beams under sustained loads. Potential failure was identified by a rapid increase in Poisson’s ratio due to tertiary creep, which occurred between 20 to 40 minutes before the sustained loading capacity was exhausted.

Keywords

Compressive arch action; Creep; Frame; Poisson's ratio; Progressive collapse; Sustained loading

Disciplines

Civil Engineering

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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