Characterization of masonry behavior under high strain rates

Abstract

The study of the dynamic properties of materials has increased in recent times. It is well established that the strain rate influences most of the materials used in construction. This effect on materials such as concrete or steel has been intensively investigated. However, similar studies on masonry materials such as clay bricks cannot be found in the literature easily. Understanding the strain rate effect on masonry materials is important for proper modelling and design of masonry structures under high velocity impacts, such as masonry parapets in bridges, or historic masonry subjected to blast loads, due to deliberate or negligent actions. This work aims at studying the behavior of masonry and its components in compression at different strain rates. A Drop Weight Impact Machine is used on historic clay brick, mortar and masonry specimens at different heights and weights introducing different levels of strain rate, ranging from 4 s-1 to 199 s-1 . The strain rate effect on the ultimate strength, Young’s modulus and strain at peak strength are determined from the experimental results. Empirical relations of dynamic increase factors (DIF) for these material properties are also presented. Finally, the study of a case study regarding the analysis of a historical structure in Portugal subjected to blast is presented and discussed for different scenarios.