Design of Concrete Gravity Load Systems for Lateral Displacements

9416466斯坦顿许多钢筋混凝土结构在北岭地震中部分或全部倒塌。 一些倒塌是由于柱的破坏，这些柱只设计用于重力荷载。 许多工程师根据柱的弯矩强度进行评估。 这是一种不适当的方法，因为真实的问题是旋转能力而不是力矩能力。 本研究将从两个方面探讨这一问题。 第一个是开发分析工具，预测层间位移，柱可以经历没有失败。 所用的方法是构建轴向力与曲率承载力的相关图，而不是传统的轴向荷载与弯矩承载力的相关图。 曲率与旋转有关，旋转又可以用来预测层间位移能力。 在分析中将考虑竖向加速度和剪切强度。 创新的柱细节将被开发，这将允许更大的非弹性旋转之前失败。 一种方法是使用框架抗横向荷载部分所需的完整抗震拉杆来详细说明所有柱。 其他细节将取决于在柱端提供局部柔性或提供局部限制以防止破裂和/或剪切破坏。 这些柱的细节将是简单的，经济的，易于检查和建设将被推荐。 这是一个北岭地震项目。 ***

9416466 Stanton A number of reinforced concrete structures collapsed, either partially or totally, in the Northridge earthquake. Some of the collapses were attributed to the failure of columns which were designed for gravity loads only. Many engineers perform the evaluation in terms of the moment strength of the columns. This is an inappropriate approach because the real issue is rotation capacity and not moment capacity. The research undertaken here will investigate two aspects of the issue. The first is to develop analytical tools with which to predict the story drift that a column can undergo without failure. The approach to be used is to construct interaction diagrams relating axial force to curvature capacity, rather than the conventional axial load to moment capacity. Curvature is related to rotation which in turn can be used to predict story drift capacity. The vertical accelerations and the shear strength will be taken into consideration in the analysis. Innovative column details will be developed that will permit larger inelastic rotations before failure. One approach is to detail all columns using the full seismic ties required in the lateral load resisting part of the frame. Other details will be developed that depend on either providing local flexibility at the column ends or on providing localized confinement to prevent bursting and/or shear failure. These column details which will be simple, economical, and easy to inspect and build will be recommended. This is a Northridge Earthquake project. ***