Evaluation and Design Requirements for RC "Gravity" Columns

在建筑抗震设计中，通常的做法是假设建筑物的一部分承受所有的地震力，而建筑物的其余部分只承受重力。虽然规范规定要求重力承载系统的设计要能适应施加的横向漂移，但目前尚不清楚检查施加的漂移的程序是否足够，也不确定许多工程师是否真的检查了重力系统的横向漂移。以这种方式设计的一些钢筋混凝土（RC）建筑由于所谓的重力柱（不设计以抵抗侧向力的柱）的破坏而持续损坏和倒塌。本项目旨在进一步了解导致钢筋混凝土重力柱破坏的因素，并开发改进的设计方法。这一需求与现有建筑物的评估和升级有关，同样与新建筑物的设计有关。拟议的研究将使用基于实验证据的分析方法来解决这一需求，并将涉及学术研究人员和设计专业人员。具体而言，研究任务包括：(a)钢筋混凝土柱的变形能力研究；(b)研究实际建筑系统对柱子施加的变形要求；(c)审查设计和评价的实际程序；(d)将调查结果转移到有关守则/指引活动；(e)协调与正在进行的国家科学基金会研究/研究计划有关的其他北岭研究项目；(f)为NEHRP各机构汇编的专业论文系列以及其他出版物和专业报告作出贡献。这是北岭地震项目。＊＊＊

9416441 Moehle It has been common practice in building seismic design to assume part of the building resists all the seismic forces and the remainder of the building resists only gravity forces. Though code provisions require the gravity-load- carrying system to be designed to accommodate the imposed lateral drifts, it is not clear that the procedures for checking the imposed drifts are adequate, and it is not certain that many engineers actually check the gravity system for lateral drifts. Several reinforced concrete (RC) buildings designed in this way sustained damage and collapse associated with failure of the so-called gravity columns (the columns not designed to resist lateral forces. This project is to develop improved understanding of the factors leading to failure of RC gravity columns, as well as to develop improved designed approaches. This need is relevant to evaluation and upgrading of existing buildings, and equally relevant to the design of new buildings. The proposed research will address this need using analytical methods based on experimental evidence, and will involve both academic researchers and design professionals. Specifically, the research tasks include: (a) study of the deformability of reinforced concrete columns; (b) study of deformation demands imposed on columns by practical building systems; (c) examination of practical procedures for design and evaluation; (d) transfer of findings to relevant code/guidelines activities; (e) coordination of other Northridge research projects that are related to the ongoing NSF R/R program; and (f) contribution to the professional papers series to be assembled by NEHRP agencies, as well as other publications and professional presentations. This is a Northridge earthquake project. ***