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|Title:||Spall damage of concrete structures|
|Authors:||Mississippi State University. Department of Civil and Environmental Engineering.|
McVay, Mark K.
Protective structures prediction
|Publisher:||Structures Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Technical report (U.S. Army Engineer Waterways Experiment Station) ; SL-88-22.|
Abstract: Spall is defined as the ejection of fragments from the opposite side of a structural element from which it is impacted and/or impulsively loaded. This research was on the spall of reinforced concrete panels subjected to bomb fragment impacts and/or airblast loads from nearby bomb detonations. Theories of spall, tests involving spall, and current spall prediction methods were reviewed and evaluated. The current spall prediction methods did not satisfactorily predict all of the previous test results found in the literature. Forty tests were conducted on reinforced concrete walls to investigate parameters which affect spall, to evaluate prediction methods further, and to provide data with which theory and prediction methods could be improved. Theoretical calculations were conducted for airblast loads under the compressive elastic limit. The tests showed that spall is dependent upon the shape and duration of a stress wave as well as peak pressure. Scale model structures subjected to model bomb threats incurred less damage than full-scale structures subjected to full-scale bomb threats due to strain-rate effects. Thus, empirical prediction curves based upon scaled standoff distance underpredicted the damage in the full-scale tests. Cased bombs caused worse damage than equal-size bare bombs at the same standoff distances from equal walls. Thick-cased bombs caused much worse damage than equal-size thin-cased bombs at the same standoff distances from equal walls. An increase in wall thickness slightly reduced the amount of spall. Walls with close-spaced reinforcing steel suffered less damage than walls with wider-spaced reinforcing steel. Walls made of high-strength concrete suffered worse spall damage than walls made of 4,000-psi concrete subjected to the same bomb threats. Walls made of 4,000-psi concrete with 191.7 lb/yd³ of acrylic latex additive suffered less spall damage than similar concrete walls without the latex additive subjected to the same bomb threats. Walls made of 4,000-psi concrete with 80 lb/yd³ of crimped steel fibers suffered less damage than similar concrete walls without steel fibers subjected to the same bomb threats. Data on 334 tests were collected in addition to the data from the 40 tests in this study. Improved empirical prediction curves for bare and cased charges were made and are presented in this report. NOTE: This file is very large. Allow your browser several minutes to download the file.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Technical Report|
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