In-plane and out-of-plane behaviour of concrete masonry infills

在现代建筑结构中，砌体墙通常用于填充钢或钢筋混凝土框架，作为内部隔墙或外部包层。由于在评估砌体与框架之间相互作用程度方面缺乏科学信息，砌体填充体通常被视为非结构单元，并且边界框架的设计同时适用于重力和侧向荷载。砌体填充物对框架刚度和强度的贡献因此被忽略。然而，忽略填充物的贡献是一种保守的方法，这是一种误解。填充墙显著增强框架的刚度，这反过来又吸引更大的力到结构的填充区域。设计不当的填充墙被认为是造成地震中灾难性结构破坏的一个因素。另一方面，合理设计的填充物已显示出在抵抗各种类型的横向荷载方面为框架系统提供显著的强度和延展性-即使在相当大的裂缝之后。******框架体系的非线性、非弹性行为，加上砌体填料的各种材料和几何特性，使得准确评估填料对填充体系的侧向刚度和强度的贡献成为一项挑战。尽管在过去的三十年里进行了大量的实验测试和数值分析，但结果是分散的，这些研究的一些发现要么是不确定的，要么甚至是相互矛盾的。加拿大砌体设计标准CSA S304.1-04（2004）中包含的砌体填充物设计指南是基于40多年前进行的工作。使用这些指南获得的设计值与现有的实验结果存在显著差异，也与其他公认的标准（如美国规范MSJC 2013，新西兰砌体设计规范NZS 4230和欧洲规范8）的值存在显著差异。这些不一致导致了研究成果在很大程度上没有转化为行业实践的情况。***为了在结构的横向和重力荷载抵抗系统中加入砌体填充物，科学验证和行业接受的设计指南涵盖填充物的实际应用是至关重要的。因此，这一建议的动机是通过实验和分析来研究框架范围内混凝土砌体填充物的行为和能力，从而促进合理设计方法的发展。研究完成后，预计将用一系列参数量化填充和框架的行为，从而提出适用于行业实践的建设性建议。这将填补现行标准的空白，并最终影响目前的砌体填充施工实践。**

Masonry walls have been commonly used to infill steel or reinforced concrete frames either as interior partitions or exterior cladding in modern building construction. Due to a lack of scientific information in assessing the extent of interaction between the infill and the frame, the masonry infill is often treated as non-structural element and the bounding frame is designed for both gravity and lateral loading. The contribution of masonry infills to the frame stiffness and strength is therefore ignored. It is, however, a misconception that ignoring the contribution of the infill is a conservative approach. Infill walls significantly stiffen the frame, which in turn attracts larger forces to the infill region in a structure. Improperly designed Infill walls have been identified as a contributing factor to catastrophic structural failures in earthquakes. On the other hand, properly designed infills have shown to provide significant strength and ductility for the frame system in resisting various types of lateral loads-even after considerable cracking. ******The nonlinear, inelastic behaviour of the frame system coupled with the various material and geometric characteristics of masonry infills has made accurate evaluation of the infill contribution to the lateral stiffness and strength of the infilled system a challenge. Despite that much experimental testing and numerical analysis have been conducted in the past three decades, the results have been scattered and some findings from these studies were either inconclusive or even conflicting. The design guidelines for masonry infills contained in the Canadian masonry design standard, CSA S304.1-04 (2004), are based on work conducted more than 40 years ago. The design values obtained using these guidelines are found to be in significant disparity with existing experimental results and also with values obtained from other recognized standards such as American code MSJC 2013, New Zealand masonry design code NZS 4230 and Eurocode 8. These inconsistencies have resulted in the situation that research findings have not been transferred to industry practice to a large degree. ***In order to incorporate masonry infills in the lateral and gravity load resisting systems of a structure, scientifically verified and industry-accepted design guidelines that cover practical applications of infills are crucial. This proposal is hence motivated to investigate, both experimentally and analytically, the behaviour and capacity of concrete masonry infills bounded by frames so as to contribute to advancement of rational design approaches. The research, upon its completion, is expected to quantify the infill and frame behaviour with a range of parameters to a point that constructive recommendations applicable to industry practice can be made. This will fill in the gap in the current standard which will ultimately impact the current masonry infill construction practice. **