NEESR-CR: Assessment of Punching Shear Vulnerability of Slab-Column Connections with Shear Stud Reinforcement

这个奖项是一个结果的NSF 09-524计划征求“乔治E。小布朗地震工程模拟网络（NEES）研究（NEESR）”竞赛，包括密歇根大学（牵头机构），明尼苏达大学双城分校（子奖项）和明尼苏达大学杜卢斯分校（子奖项）。该项目将利用明尼苏达大学（双子城）的NEES设备场地。由柱直接支撑的板或平板框架系统组成的结构系统由于其建筑外观、功能性和经济性而广泛用于混凝土建筑。在高地震危险地区，它们已被用于高达60层的结构中，与结构墙或抗弯矩框架结合使用。由于它们在地震期间可能发生冲切破坏，抗剪钢筋通常以有头剪力钉的形式提供。 然而，作为先前NEESR项目（NSF奖0421180）的一部分进行的测试结果引起了人们对这种钢筋抗冲切性能有效性的严重关注。考虑到过去十年中建造的大量带有头部钢筋的平板结构，这些测试结果可能表明，在西海岸的下一次大地震中可能会出现潜在的重大问题。如果这确实是一个严重的问题，因为以前的NEESR测试结果似乎表明，地震工程界应该采取措施，并防止类似的情况下观察到的焊接钢连接在1994年北岭，CA earthquake.This project involves a group of researchers from three U.S. Universidad Nacional Autónoma de梅西科（UNAM）.主要研究目标是通过评估实际使用的典型头部钢筋设计的效率来估计现有板柱连接的脆弱性。在明尼苏达大学NEES-MAST实验室，将对大型板柱混凝土进行重力荷载和双向侧向位移联合作用下的试验。这些测试将允许在强地面运动期间评估带大头钉钢筋的板柱连接的脆弱性。一个平板结构的振动台试验也将在墨西哥国立自治大学进行，以评估在动态激励下与有头钢筋连接的响应。智力价值：这项研究将产生所需的信息，使执业工程师和建筑官员，以确定脆弱的平板结构与有头钢筋。这是少数几个实验研究在大地震确认这些担忧之前引发对现代结构安全性的重大担忧的例子之一。因此，本项目所积累的知识对于保护生命和减少地震中平板结构可能发生的破坏或倒塌所造成的经济损失具有重要意义。更广泛的影响：教育和推广计划的目标是本科生和大学预科生。 通过使用明尼苏达大学NEES设备现场的远程参与功能，这些学生将有机会见证实验计划的各个步骤，并远程参加有关地震基础知识和地面运动混凝土结构设计的讲座。该项目的数据将通过NEES数据库存档并向公众提供。

This award is an outcome of the NSF 09-524 program solicitation "George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)" competition and includes the University of Michigan (lead institution), the University of Minnesota, Twin Cities (subaward), and the University of Minnesota, Duluth (subaward). This project will utilize the NEES equipment site at the University of Minnesota (Twin Cities). Structural systems that consist of slabs directly supported by columns or flat plate frame systems are widely used in concrete construction because of their architectural appearance, functionality, and economy. In regions of high seismic hazard, they have been used in structures of up to 60 stories, in combination with structural walls or moment resisting frames. Because of their potential for punching shear failures during earthquakes, shear reinforcement is often provided in the form of headed shear studs. Results from a test conducted as part of a prior NEESR project (NSF award 0421180), however, have raised serious concerns about the effectiveness of this reinforcement for punching shear resistance. Given the large number of flat-plate structures with headed reinforcement built in the last decade, these test results could be an indication of a latent major problem that could surface in the next large earthquake on the west coast. If this is indeed as serious of a problem as the prior NEESR test results seem to indicate, the earthquake engineering community should act with diligence and prevent a situation similar to that observed with welded steel connections during the 1994 Northridge, CA earthquake.This project involves a group of researchers from three U.S. universities and the Universidad Nacional Autónoma de México (UNAM). The main research objective is to estimate the vulnerability of existing slab-column connections by evaluating the efficiency of typical headed reinforcement designs used in practice. Large-scale slab-column subassemblies will be tested under combined gravity load and biaxial lateral displacements at the University of Minnesota NEES-MAST Laboratory. These tests will allow the evaluation of the vulnerability of slab-column connections with headed stud reinforcement during strong ground motions. Shake table tests of a flat-plate structure will also be conducted at UNAM for evaluation of the response of connections with headed reinforcement under dynamic excitation.Intellectual Merit: This research will generate needed information that will allow practicing engineers and building officials to identify vulnerable flat-plate construction with headed reinforcement. This is one of a very few instances in which experimental research has prompted major concerns about the safety of modern structures before those concerns are confirmed by a major earthquake. Thus, the knowledge developed in this project could have a major impact in terms of protecting lives and reducing financial losses associated with potential failure or collapse of flat-plate structures during an earthquake.Broader Impacts: The education and outreach program targets undergraduate and pre-college level students. Through the use of the teleparticipation capabilities at the University of Minnesota NEES equipment site, these students will have the opportunity to witness the various steps of the experimental program and remotely attend lectures on the basics of earthquakes and design of concrete structures for ground motions. Data from this project will be archived and made available to the public through the NEES data repository.