Enhancement of structural response in members built with engineered cementitious composites (ECC)

工程水泥复合材料(ECC)砂浆是一种纤维增强的水泥基材料，旨在表现出高延展性。嵌入在混合物中的聚乙烯醇纤维(PVA)允许ECC达到3%至5%的极限拉伸应变，而没有明显的损伤。ECC不像普通混凝土在断裂时产生单一的、宽的拉伸裂缝，而是形成多个微裂缝，这些微裂缝在第一次裂缝后转化为假塑性行为。这使得用ECC制造的结构构件可以产生更大的变形，因为受拉的纤维可以承受高达传统混凝土500倍的变形。ECC已被用于日本高层建筑的连梁和剪力墙、桥梁上部结构，并用于缓解大坝的裂缝。在北美，ECC已被用于一些建筑和桥梁结构。在加拿大，这种引人注目的材料用于结构目的在加拿大非常有限。人们认识到，要更广泛地使用ECC，需要彻底了解这种创新材料的机械性能。剪切性能是研究的一个特别重要的方面，因为高估结构构件的剪切强度可能会导致脆性和灾难性的破坏。本研究旨在评估使用艾伯塔省本地原材料制造ECC的可行性，表征其材料性能，并研究ECC的剪切性能。这项研究的目的是证明ECC是一种可行的替代传统混凝土的材料，具有优异的回弹、剪切强度和拉伸延展性。

Engineered Cementitious Composite (ECC) mortar is a fibre-reinforced, cement-based material designed to exhibit high ductility in tension. Polyvinyl alcohol fibres (PVA) embedded in the mix allows ECC to reach ultimate tensile strains from 3% to 5% with no visible damage. Instead of developing a single, wide crack in tension as plain concrete does when it fractures, ECC develops multiple micro-cracks which translate into a pseudo-ductile behaviour after first crack. This allows for greater deformations in structural members made with ECC, since the fibres in tension can sustain deformations up to 500 times more than conventional concrete. ECC has been used at the coupling beams and shear walls of high-rise buildings in Japan, bridge superstructures, and to mitigate cracks in dams. In North America, ECC has been used in a few building and bridge structures. In Canada, the use of this remarkable material for structural purposes in Canada is very limited. It is recognized that a more widespread use of ECC requires a thorough understanding of the mechanical properties of this innovative material. Shear behaviour is a particularly important aspect to study since overestimating the shear strength of structural members may lead to brittle and catastrophic failures. This research intends to assess the feasibility to fabricate ECC with raw materials local to the province of Alberta, characterize its material properties, and investigate the shear behaviour of ECC. The goal of the study is to show that ECC is a viable alternative to conventional concrete, with superior resilience, shear strength and ductility in tension.