Collaborative Research: Engineered Earth Masonry for Affordable Seismic Resistant Low-Rise Buildings

美国对可持续和抗灾能力强，但又负担得起的家庭和企业低层建筑的需求持续不断。本研究的目的是探讨高品质加筋土砌体（REM）的抗震低层建筑的可行性。这一目标将通过使用不可生物降解的再生塑料纤维与内部钢筋相结合，将可持续和适合当地但易碎的未烧制的泥土砌体转化为更坚固，更具延展性的系统来实现。本研究将探讨REM作为低层工业建筑和工棚的低成本选择，以期通过降低建筑和维护成本促进小型工厂和仓库的发展，从而促进经济发展。本研究的技术目标如下：（1）设计，原型，并验证一个负担得起的和高品质的REM系统抗震低层建筑，（2）制定，验证和实施一个新的数值模型，以准确和有效地预测REM墙的结构响应。假设是：v（1）用9%或更少的水泥稳定的土块和砂浆工程，用1%或更少体积分数的再生塑料纤维加固，结合内部钢筋，将改变REM的强度和延性，使其适合抗震建筑，和（2）基于新开发的非线性宏单元（ME）的计算效率高的数值模型，其运动学由尽可能少的自由度描述，将能够准确预测REM结构在静态和动态载荷下的响应。这项研究将分三个阶段进行。首先，将通过材料和组件的载荷测试，对选定的原型砌块-砂浆组合（无钢筋、纤维增强和纤维增强灌浆钢筋）进行表征。将为第二阶段选择一个候选的加固系统。三维（3D）数字图像相关（3D-DIC）将用于测量全场变形图，并为数值模型的开发提供信息。由此产生的材料，砂浆接缝，REM组合本构模型将制定详细的有限元（FE）模型。其次，性能数据将通过大规模测试和3D-DIC监测REM墙准静态循环荷载。研究结果将为新的结构ME模型及其FE代码的制定和验证提供信息。第三，也是最后，基于有限元模型的大规模标本将开发的数值和实验结果之间的比较的基础上。由此产生的第一代ME模型将用于初步估计抗震设计系数和因素，以确定可行性。此外，还将对代表性的可再生能源材料和建筑物的可持续性相关参数和建筑成本进行初步量化，以便为与替代系统（例如轻型木结构）进行比较以及进行生命周期成本分析提供依据。

There is a continuing demand in the United States for sustainable and hazard-resilient but highly affordable low-rise buildings for households and businesses. The goal of this research project is to investigate the feasibility of high-quality reinforced earth masonry (REM) for seismic resistant low-rise buildings. This goal will be achieved by transforming sustainable and locally appropriate but brittle unfired earth masonry into a stronger and more ductile system by using non-biodegradable recycled plastic fibers combined with internal steel reinforcement. This research will investigate REM as a low-cost option for low-rise industrial buildings and sheds, with a vision of fostering the development of small plants and warehouses by reducing construction and maintenance costs, thus promoting economic development. The technical objectives of this research are the following: (1) to engineer, prototype, and verify an affordable and high-quality REM system for seismic resistant low-rise buildings, and (2) to formulate, verify and implement a new numerical model to accurately and efficiently predict the structural response of REM walls. The hypotheses are:v(1) engineering of earth blocks and mortar stabilized with nine percent or less cement, and reinforced with one percent or less volume fraction of recycled plastic fibers, combined with internal steel reinforcement, will change the strength and ductility of REM, making it suitable for seismic resistant buildings, and (2) computationally efficient numerical models based on newly developed nonlinear macroelements (MEs), whose kinematics are described by the smallest possible number of degrees of freedom, will enable the accurate prediction of the response of REM structures subject to static and dynamic loads. This research will be conducted in three phases. First, selected prototype block-mortar combinations (unreinforced, fiber reinforced, and fiber reinforced with grouted steel bars) will be characterized through load testing of materials and assemblages. A candidate reinforced system will be selected for the second phase. Three-dimensional (3D) digital image correlation (3D-DIC) will be used to measure full-field deformation maps and inform the development of numerical models. The resulting constitutive models for materials, mortar joints, and REM assemblages will serve to formulate detailed finite element (FE) models. Second, performance data will be obtained through large-scale testing and 3D-DIC monitoring of REM walls subject to quasi-static cyclic loading. The results will inform the formulation and validation of new structural ME models and their FE code implementation. Third and final, ME-based FE models of the large-scale specimens will be developed based on the comparison between numerical and experimental results. The resulting first-generation ME models will be used for a preliminary estimate of seismic design coefficients and factors to establish feasibility. In addition, a preliminary quantification of sustainability-related parameters and construction cost for representative REM materials and buildings will be performed to provide a basis for comparison with alternative systems, for example, light-framed wood, as well as life-cycle cost analysis.