SGER: Implosion of a Building and Progressive Collapse Analysis of Structures

摘要-0601258防止渐进性倒塌是一个非常重要的社会问题，特别是在1995年Murrah联邦大厦遭到袭击和2001年9月11日恐怖袭击之后。这种预防需要了解系统级的行为，但是实际的数据很少，因为系统级的测试非常昂贵。渐进式倒塌本质上是一个系统级问题，最初的局部破坏从一个元素扩散到另一个元素，最终导致整个结构或其不成比例的大部分倒塌（ASCE 7, 2002）。我们对这种条件下的倒塌机制和结构能力的理解是有限的，因为有关单元和整体结构行为的相关实验结果很少。本提案描述了一项探索性研究计划，该计划从计划内爆的全尺寸钢筋混凝土（RC）结构中获得真实可靠的数据，以确定其在施加预计划损伤情景后的能力和潜在的渐进倒塌机制。从建筑物中获得的数据是真实可靠的，因为除了在爆炸柱上打一些小洞放置炸药外，在爆炸前不需要对RC梁和柱施加任何结构破坏。内爆层中的非结构元素将被移除，以便于坍塌。非结构单元的移除不会对结构的破坏机制产生太大的影响，而且可以更容易地检查结构单元的变形能力，而不必考虑非结构单元带来的复杂性。该研究计划将作为证明收集此类数据的可能性的第一步，以及数据在开发可靠的能力模型以及可靠的渐进崩溃分析程序中的价值。GSA（2003）和DOD（2004）使用移除一根柱子作为初始局部破坏的情景来检查结构的渐进倒塌。在建筑物主内爆之前，对部分柱进行了爆破，以评估建筑物的反应和适当的内爆策略。基于与control Demolition Inc的现有合作，这些专栏将与CDI专家共同选择。该建筑将分两个阶段进行仪器检测；一次是在爆炸试验期间一次是在主内爆期间。第一阶段将提供有关建筑物故障后系统响应的宝贵信息，这将大大有助于改进建模技术和移除承重元件后的需求估计。从第二阶段收集的数据将用于开发由于施加的大位移和力而导致RC结构元件倒塌的能力模型。实验的主要目的是：了解渐进式坍塌和破坏模式的机制；评估程序的渐进倒塌分析目前使用的工程师；确定钢筋细部、接缝和楼板隔板对逐渐倒塌的影响；确定关键构件的变形能力；并对先进的材料和几何非线性结构进行了校核和动力分析。智力优势：在这项探索性和创新性研究中，将进行全面的系统级实验计划，以收集具有预先计划损伤的RC结构的可靠响应。利用这些数据，将研究配筋细部对连续倒塌的影响。记录的数据将用于开发能力模型，进而可用于更可靠地估计结构的潜在渐进倒塌。此外，这些数据将用于校准和验证先进的非线性动力分析的渐进崩溃。更广泛的影响：可靠的渐进式倒塌分析的发展导致识别具有潜在危险的结构，这反过来又导致更好地分配有限的资源用于结构的修复和开发具有成本效益的现有结构改造计划。该项目的成果也将有助于量化新结构现行规范中结构完整性要求的有效性。此外，研究结果可用于检查现有结构的防倒塌性能及其修复。

Abstract-0601258Preventing progressive collapse is a gravely important problem for society, particularly after the attacks on the Murrah Federal building in 1995 and the terrorist attacks on September 11, 2001. Such prevention requires knowledge of system-level behavior, but there is very little actual data because system-level tests are prohibitively expensive. Progressive collapse is by nature a system-level problem where the spread of an initial local failure from element to element eventually results in the collapse of an entire structure or a disproportionately large part of it (ASCE 7, 2002). Our understanding of collapse mechanisms and structural capacities under such conditions is limited because relevant experimental results on the behavior of elements and whole structures are scarce.This proposal describes an exploratory research plan that obtains realistic and reliable data from a full-scale reinforced concrete (RC) structure scheduled to be imploded, in order to determine its capacity and potential progressive collapse mechanism after imposing preplanned damage scenarios. The data obtained form the building are realistic and reliable, because there is no need to impose any structural damage to RC beams and columns prior to the implosion other than making some small holes in exploding columns to place explosives. The nonstructural elements in the imploding stories will be removed for the ease of collapse. The removal of nonstructural elements will not considerably affect the collapse mechanism, yet makes it easier to examine the deformation capacity of structural elements without the complication introduced by nonstructural elements. The research program will serve as a first step to demonstrate the possibility of collection of such data, and the value of the data in developing reliable capacity models as well as procedures for reliable progressive collapseanalysis. GSA (2003) and DOD (2004) use scenarios with the removal of one column as the initial local failure to examine progressive collapse of structures. Prior to the main implosion of a building, some of the columns are exploded to evaluate the response of the building and proper implosion strategy. Based on an existing collaboration with the Controlled Demolition Inc, these columns will be chosen jointly with CDI experts. The building will be instrumented at two stages; one during the explosion tests and one during the main implosion. The first stage will provide invaluable information about the post-failure system response of the building, which will significantly help improve modeling techniques and estimation of demands following the removal of load bearing elements. The data collected from the second stage will be utilized to develop capacity models for collapse of RC structural elements due to the imposed large displacements and forces. The main objectives of the experiment are to: understand mechanisms of progressive collapse and failure modes; evaluate procedures for progressive collapse analysis currently used by engineers; determine effects of reinforcement details, joints and floor diaphragms on progressive collapse; identify deformation capacities of critical elements; and calibrate and verify advanced material and geometric nonlinear dynamic analysis of the structure.Intellectual Merit: In this exploratory and innovative research, a full-scale system-levelexperimental program will be carried out to collect reliable responses from a RC structure with preplanned damage. Utilizing the data, the effects of reinforcement detailing on progressive collapse will be studied. The recorded data will be used to develop capacity models, which in turn can be used to more reliably estimate potential progressive collapse of structures. Furthermore, the data will be used to calibrate and verify advanced nonlinear dynamic analysis of progressive collapse.Broader Impact: Development of reliable progressive collapse analysis leads to identifyingstructures that are potentially hazardous, which in turn results in better allocation of limited resources in rehabilitation of structures and development of cost-effective retrofit plans for existing structures. The outcomes of this project will also help quantify the effectiveness of structural integrity requirements in current codes for new structures. Furthermore, the outcomes can be used in examining collapse prevention performance of existing structures and their rehabilitation.