Resistance of Concrete Masonry Walls with Membrane Catcher Systems Subjected to Blast Loading

Over recent decades, three distinct methods have evolved that are currently being used to generate resistance functions for single-degree-of-freedom analyses of unreinforced masonry walls subjected to blast loading. The degree of differences in these resistance definitions depends on whether the wall is assumed to be simply supported or whether compression arching forces result from rotation restraint at the supports. The first method originated in the late 1960s as a result of both experimental and analytical research sponsored by the US Department of Defense. That method, referred to as the Wiehle method, is the basis of Unified Facilities Criteria 3-340-02 and other derived analytical software such as the Wall Analysis Code developed by the US Army Corps of Engineers, Engineer Research and Development Center. The second method is based on elastic mechanics and an assumed linear decay function that follows and is the basis of the widely used Single-Degree-of-Freedom Blast Effects Design Spreadsheets software distributed by the US Army Corps of Engineers, Protective Design Center. The third method is largely based on concrete and masonry behavioral theories developed by Paulay and Priestly in the early 1990s. This article systematically compares the resistance methodologies for arching and non-arching scenarios, demonstrates the implications by plugging the disparate resistance functions into blast load single-degree-of-freedom models, compares the analytical results to full-scale blast test results, and offers conclusions about the accuracy and efficacies of each method.

Section: Review Of Static Resistance Definitionsmentioning

confidence: 99%

Assessment of resistance definitions used for blast analysis of unreinforced masonry walls

Gagnet

Hoemann

Davidson

2017

“…Structural frames infilled with unreinforced concrete masonry unit walls are very common all over the world. CMU walls are frequently used in buildings because they offer a costeffective option and can satisfy many building requirements; however, they are extremely susceptible to blast pressure, resulting in wall collapse, fragmentation, and severe injury to occupants (Wu, Hao 2007;Moradi 2007;Hao, Tarasov 2008;Wang, Hao, Ding, Li 2009;Moradi, Dinan, Bewick, Davidson 2011;Bazhenov, Kibetz, Kruszka 2012). Consequently, there is a need to retrofit CMU walls to increase their resistance to blast loading.…”

Section: I In Nt Tr Ro Od Du Uc Ct Ti Io On Nmentioning

confidence: 99%

Simulation of Retrofitted Unreinforced Concrete Masonry Unit Walls under Blast Loading

Aghdamy

Griffith

2013

This paper describes an investigation into the effectiveness of using spray-on nano-particle reinforced polymer and aluminium foam as new types of retrofit material to prevent the breaching and collapse of unreinforced concrete masonry walls subjected to blast over a whole range of dynamic and impulsive regimes. Material models from the LS-DYNA material library were used to model the behaviors of each of the materials and its interface for retrofitted and unretrofitted masonry walls. Available test data were used to validate the numerical models. Using the validated LS-DYNA numerical models, the pressure-impulse diagrams for retrofitted concrete masonry walls were constructed. The efficiency of using these retrofits to strengthen the unreinforced concrete masonry unit (CMU) walls under various pressures and impulses was investigated using pressure-impulse diagrams. Comparisons were made to find the most efficient retrofits for masonry walls against blasts.

“…The bonded approach typically involves the application of a thin layer of a spray-on or trowel-on elastomer. The effectiveness of the bonded approach and the development of resistance functions has been presented previously (Davidson et al, 2004(Davidson et al, , 2005Moradi et al, 2008Moradi et al, , 2009Moradi et al, , 2011 and is not the focus of the present article. The unbonded method is often referred to as a "catcher system" since it simply acts as a barrier that catches the wall debris.…”

Section: Introductionmentioning

confidence: 99%

Blast resistance of membrane retrofit unreinforced masonry walls with flexible connections

Gagnet

Hoemann

Davidson

2017

Unreinforced masonry infill walls are one of the most economical and widely used exterior wall systems. However, they can produce secondary fragments due to their brittle failure modes when subjected to an impulsive blast load. One retrofit to reinforce existing masonry walls is to install a membrane that prevents fragments from entering the building's interior. Previous research focused on defining the resistance provided by the wall membrane system, but did not include flexibility of the attachments and their influence on the retrofitted wall system. This article addresses that issue through (1) a review of existing membrane retrofit resistance definitions, (2) a derivation of the resistance definition that includes connection flexibility, (3) validation of the derived resistance definition through nonlinear finite element analyses, and (4) comparison of the resistance in a single-degree-of-freedom framework against full-scale blast testing.