Use of High-Performance Fiber Reinforced Cement Composites to Increase the Displacement Capacity of Structural Walls

结构墙被广泛用作位于地震区的低层和中层结构中的抗横向荷载元件;此外，它们通常被认为是不符合现行规范要求的现有结构的主要改造措施。建议的研究的主要重点是开发一种新的设计钢筋混凝土（RC）结构墙通过使用高性能纤维增强水泥复合材料（HPFRCCs）。这些材料提供拉伸应变硬化响应和高压缩应变能力。本计画将首先进行一实验研究，以了解在位移反向作用下，以HPFRCC材料建造之结构墙之剪力与弯曲行为。这个实验阶段将包括测试几个蹲和细长HPFRCC结构墙与聚乙烯（光谱）或钢纤维增强。重点将放在研究变量的影响，如材料开裂后的强度和应变能力，墙的高宽比，剪应力水平和钢筋的详细说明的HPFRCC结构墙的行为。分析研究的目的是建立模型来预测在位移反向作用下，矮桩和细长HPFRCC墙的剪切和弯曲性能。为此目的，现有的理论开发来预测钢筋混凝土构件的反应将被修改，以占上级拉伸和压缩性能的HPFRCC材料。还将开发简化模型，以估计剪切强度与位移的关系和对应于HPFRCC结构墙的各种性能水平的位移限值。使用压杆和拉杆模型，强度因子开发的压杆和拉杆材料和墙壁测试，将探讨预测HPFRCC墙的剪切强度。最后，将为抗震HPFRCC墙制定钢筋详细要求的规定。

Structural walls are widely used as lateral load resisting elements in low- and medium-rise structures located in seismic zones; moreover, they are often considered a primary retrofit remedy for existing structures that do not meet current code requirements. The main focus of the proposed research is to develop a new design for reinforced concrete (RC) structural walls through the use of high-performance fiber reinforced cement composites (HPFRCCs). These materials offer a tensile strain-hardening response, and high compression strain capacity. In this project, an experimental study will be first conducted to understand the shear and flexural behavior of structural walls constructed with HPFRCC materials under displacement reversals. This experimental phase will include the testing of several squat and slender HPFRCC structural walls reinforced with either polyethylene (Spectra) or steel fibers. Emphasis will be placed on studying the effect of variables such as material post-cracking strength and strain capacity, wall aspect ratio, shear stress level and reinforcement detailing on the behavior of HPFRCC structural walls. Analytical studies will be aimed at developing models to predict the shear and flexural behavior of both squat and slender HPFRCC walls under displacement reversals. For this purpose, existing theories developed to predict the response of reinforced concrete members will be modified to account for the superior tension and compression behavior of HPFRCC materials. Simplified models will also be developed to estimate the shear strength vs. displacement relationship and displacement limits corresponding to various performance levels in HPFRCC structural walls. The use of strut-and-tie models, with strength factors developed for struts and ties from material and wall tests, will be explored to predict the shear strength of HPFRCC walls. Finally, provisions for reinforcement detailing requirements will be developed for seismic-resistant HPFRCC walls.