Design of Concrete Gravity Load Systems for Lateral Displacements

9416466斯坦顿在北岭地震中，许多钢筋混凝土结构部分或全部倒塌。一些坍塌归因于仅为重力荷载设计的柱子的故障。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，因为真正的问题是旋转能力，而不是力矩能力。在这里进行的研究将从两个方面探讨这一问题。首先是开发分析工具，用来预测一个专栏可以不失败地经历的故事漂移。所采用的方法是建立轴力与曲率能力之间的相互作用图，而不是传统的轴力与弯矩能力之间的相互作用图。曲率与旋转有关，而旋转又可以用来预测故事的漂移能力。在分析中将考虑竖向加速度和抗剪强度。将开发创新的柱细节，允许在失效前进行更大的非弹性旋转。一种方法是使用框架的抗侧向荷载部分所需的全部抗震纽带来详述所有柱。将开发其他细节，其依赖于在柱端提供局部弹性或依赖于提供局部约束以防止破裂和/或剪切破坏。这些列细节将是简单，经济，易于检查和建造将被推荐。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. ***