Seismic Response of Low-Rise Masonry Buildings with Flexible Roof Diaphragms PDF Download
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Author: Gregory L. Cohen
Publisher:
ISBN: 9781423523277
Category :
Languages : en
Pages : 147
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Book Description
This study compares the responses from shaking-table testing and analytical predictions evaluated in the context of geometric scaling, to provide a coherent description of the seismic response of low-rise masonry buildings with flexible roof diaphragms. Two half-scale, low-rise reinforced masonry buildings with flexible roof diaphragms are subjected to carefully selected earthquake ground motion on the Tri-axial Earthquake and Shock Simulator at the Construction Engineering Research Laboratory. Damage to the half-scale specimens is assessed using published protocols. Geometric scaling analysis relates response and damage of the half-scale specimens to those of the full-scale prototype structures. Linear elastic modeling is simplified to a generalized two-degrees-of-freedom idealization. Response-spectrum analysis of such an idealization is accurate and justified for prediction of dynamic response of the half-scale specimens and the corresponding full-scale prototype. It is shown that low-rise masonry buildings with flexible roof diaphragms can be designed for seismic loads as single-degree-of- freedom systems, using the degree of freedom associated with the in-plane response of the diaphragm in the building's transverse direction, rather than the degree of freedom associated with the in- plane responses of the shear walls.
Author: Gregory L. Cohen
Publisher:
ISBN: 9781423523277
Category :
Languages : en
Pages : 147
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Book Description
This study compares the responses from shaking-table testing and analytical predictions evaluated in the context of geometric scaling, to provide a coherent description of the seismic response of low-rise masonry buildings with flexible roof diaphragms. Two half-scale, low-rise reinforced masonry buildings with flexible roof diaphragms are subjected to carefully selected earthquake ground motion on the Tri-axial Earthquake and Shock Simulator at the Construction Engineering Research Laboratory. Damage to the half-scale specimens is assessed using published protocols. Geometric scaling analysis relates response and damage of the half-scale specimens to those of the full-scale prototype structures. Linear elastic modeling is simplified to a generalized two-degrees-of-freedom idealization. Response-spectrum analysis of such an idealization is accurate and justified for prediction of dynamic response of the half-scale specimens and the corresponding full-scale prototype. It is shown that low-rise masonry buildings with flexible roof diaphragms can be designed for seismic loads as single-degree-of- freedom systems, using the degree of freedom associated with the in-plane response of the diaphragm in the building's transverse direction, rather than the degree of freedom associated with the in- plane responses of the shear walls.
Author: Steven C. Sweeney
Publisher:
ISBN:
Category : Flexible diaphragm
Languages : en
Pages : 38
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Book Description
This paper provides an integrated approach to the seismic evaluation of low-rise reinforced masonry buildings with flexible roof diaphragms. The paper is divided into four phases. In Phase 1 (Behavior), results from shaking-table testing, quasi-static testing, and analytical predictions are integrated to provide a coherent description of the seismic response of low-rise reinforced masonry buildings with flexible roof diaphragms. Two half-scale, low-rise reinforced masonry buildings with flexible roof diaphragms are subjected to earthquake ground motions on the Tri-axial Earthquake and Shock Simulator at the United States Army Construction Engineering Research Laboratory, Engineer Research and Development Center. Following the shaking-table tests, diaphragms and top four courses of attached masonry walls are salvaged from the half-scale structures and tested quasi-statically in their own plane. A new index, the diaphragm drift ratio, is introduced to describe the potential for diaphragm damage. In Phase 2 (Analysis), coordinated analytical modeling is developed and implemented to corroborate and extend the results of that experimental work, and to examine the efficacy and accuracy of different analytical modeling approaches. Linear elastic finite-element models, simplified two-degree-of-freedom models, and nonlinear lumped-parameter models are developed; all agree well with measured responses. In Phase 3 (Seismic Evaluation), the first two phases are used to develop and verify a simple extension to FEMA 310, the predominant seismic evaluation methodology for low-rise reinforced masonry buildings with flexible diaphragms. In Phase 4 (Application and Verification), the proposed extension, applied to four existing buildings, is shown to be simple, useful, and necessary.
Author: Franklin Lehr Moon
Publisher:
ISBN:
Category : Composite materials
Languages : en
Pages : 1298
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Book Description
As a capstone to several Mid-America Earthquake Center (MAE Center) projects, a full-scale two story unreinforced masonry (URM) building was tested following the application of several retrofit techniques, which included the use of fiber reinforced polymer (FRP) overlays, near surface mounted (NSM) rods, vertical unbonded post-tensioning, and joist anchors. The test structure was composed of four URM walls, flexible timber diaphragms and interior stud walls, and was designed and built following construction practices consistent with those used in Mid-America prior to 1950. Initial testing subjected both the roof diaphragm and in-plane walls to slowly applied lateral load reversals in an unreinforced sate. Following this series of tests, each in-plane wall was retrofit and retested. Experimental results indicated that global issues such as flange participation and the effects of overturning moment substantially impacted the response of primary components both before and after retrofit. FRP retrofit techniques resulted in strength increases up to 32% and displayed a pseudo-ductile response caused by progressive debonding. For cases where such retrofits forced sliding failures, large increases in energy dissipation resulted. The use of vertical unbonded post-tensioning resulted in strength increases between 40%-60%; however, piers displayed a tendency to switch from a ductile rocking/sliding mode to a more brittle diagonal tension mode. In addition, results highlighted the need for retrofit schemes to employ both horizontal and vertical reinforcement to prevent progressive crack opening that can decrease wall displacement capacity. Based on the experimental results, the model implied by the "Prestandard for the Rehabilitation of Existing Structures," FEMA 356, for the analysis of in-plane URM walls was modified and extended to (1) include the effect of FRP pier retrofits and (2) consider the global effects of URM structures. The resulting model displayed reasonable estimates of measured response both before and after retrofit, with an average error of 14%. In addition, the proposed model displayed improvements over the current model from 14% to 66%. Based on the results of sensitivity analyses this improved accuracy was primarily attributed to the consideration of global effects.
Author: Ho Jung Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 520
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Author: Gregory L. Cohen
Publisher:
ISBN:
Category : Building, Brick
Languages : en
Pages : 38
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Author:
Publisher:
ISBN:
Category : Earthquake engineering
Languages : en
Pages : 22
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Author: Steven C. Sweeney
Publisher:
ISBN:
Category : Buildings
Languages : en
Pages : 80
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Author: Steven C. Sweeney
Publisher:
ISBN:
Category : Buildings
Languages : en
Pages : 114
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Author: Gregory L. Cohen
Publisher:
ISBN:
Category : Buildings
Languages : en
Pages :
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Author:
Publisher:
ISBN: 9781564240354
Category :
Languages : en
Pages :
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