建筑结构倒塌过程模拟与防倒塌设计

Simulation of collapse process and design method to resist collapse for building structures

针对结构性能的数值模拟方法进行了综合分析,基于离散单元法提出了结构倒塌分析的理论模型。通过试验研究了混凝土块体间碰撞的力学行为,并结合扩展的数值分析建立了混凝土块体在不同碰撞形式下的计算模型。针对建筑物内的局部爆炸作用,在分析构件反应的基础上采用离散单元法对结构平面及空间倒塌过程进行了数值模拟。建立了适用于任意加载路径的材料弹簧力-位移本构关系,据此分析了地震作用下钢筋混凝土框架结构以及砌体结构空间倒塌过程。采用基于OpenGL的图形建模技术,实现了结构倒塌过程数值模拟结果的三维可视化。模拟结果与振动台模型试验结果及工程实测结果比较表明,所采用的离散单元法适合结构大变形阶段的分析。为提高计算效率和精度,有必要采用多尺度的模拟分析。另外,对不同荷载及作用下建筑结构抗倒塌设计方法进行了总结。并指出结构参数对抗连续倒塌性能的影响、结构倒塌机理、实用的防连续倒塌设计方法以及地震作用下结构防倒塌定量设计方法等方面尚待深入研究,以便建立相应的防倒塌设计规范。

Numerical methods for simulating structural behavior of buildings are reviewed and analyzed.Based on discrete element method （DEM） in which the structural elements are discretized reasonably,a new numerical simulation model is employed in this paper to analyze the collapse process of building structures.Theoretical model to calculate the impact action between discrete concrete blocks or elements is proposed through collision tests.By studying the structural responses under blast loads,both plane and spatial collapse processes of reinforced concrete frame structures are simulated.By defining the constitutive relationships with failure criterion for springs in material level under arbitrary loading paths,the numerical simulation of spatial collapse process for reinforced concrete frame structures and masonry structures are also performed.Comparing with the shaking table tests and the results obtained from the practical project,it can be concluded that the proposed DEM based simulation method can be commendably used to simulate the collapse process of building structures by choosing rational discretization plan and reasonable impact model.To improve the simulation accuracy and increase the speed of calculation,it is better to adopt the multi-scale simulation technology in the future.The design method to resist progressive collapse is also discussed.According to the state of the art,further research is recognized to be needed to identify the structural parameters influencing the progressive collapse behavior and the collapse mechanism of building structures.The practical design method for progressive collapse resistant design and the quantitative design method to resist collapse of building structures under earthquake should be developed and implemented in future code.