Response of Arching Unreinforced Concrete Masonry Walls to Blast Loading
Publication: Journal of Structural Engineering
Volume 137, Issue 10
Abstract
New standards for blast protection of buildings are currently being developed in the United States and Canada. In this regard, both standards are considering unreinforced masonry (URM) walls as particularly vulnerable to blast events and may not be used in blast-resisting structural systems. In this paper, the effectiveness of enforcing arching action as a cost-effective hardening technique for vertically spanning one-way URM walls under blast loads is investigated. A total of eight full-scale concrete-block URM walls were subjected to blast loads generated by high explosives. Enforcing URM walls arching between rigid supports significantly enhanced their out-of-plane blast resistance compared to similar nonarching (flexural) URM walls. Moreover, no fragments or debris were observed on the leeward side of the arching walls, indicating the potential of the proposed hardening technique in reducing the hazard level on the occupants of buildings with exterior URM walls. The improved performance is attributed to the formation of hinges at the walls’ supports and midheights. This three-hinged arch mechanism allowed the walls to develop large in-plane compressive forces, which subsequently increased their out-of-plane resistances and prevented flying debris due to increased friction forces between the masonry courses. Comparing the observed strength of the arched walls to their strength predicted by existing models showed a significant underestimation of the actual wall strengths. The results of the study clearly demonstrate that, with minimal structural intervention, URM walls can significantly improve the building envelope performance and contribute to the structural resistance of blast loads.
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Acknowledgments
The following organizations are gratefully acknowledged for their support toward this study: the Chemical, Biological, Radiological/Nuclear and Explosives Research and Technology Initiative (CRTI Project No. UNSPECIFIED06-015TD) for the financial support, the Canadian Explosives Research Laboratory (CERL) for conducting the blast tests, the Canadian Armed Forces for the use of the test range, the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Concrete Masonry Producers Association (CCMPA) for donating the masonry blocks, the Canada Masonry Design Center (CMDC) for building the walls, and the Center for Effective Design of Structures (CEDS) at McMaster University funded through Ontario Research and Development Challenge Fund (ORDCF), a program of the Ministry of Research and Innovation (MRI), for their financial support.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 137 • Issue 10 • October 2011
Pages: 1205 - 1214
Copyright
© 2011 American Society of Civil Engineers.
History
Received: May 30, 2010
Accepted: Nov 11, 2010
Published online: Nov 16, 2010
Published in print: Oct 1, 2011
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