Reliability assessment of damaged ductile RC frame structures against progressive collapse in close-in detonation conditions
Date of Issue2009
School of Civil and Environmental Engineering
A new approach is developed based upon the alternative load path (ALP) concept to assess the reliability of multi-storey ductile frame structures subjected to one column failure under close-in detonation conditions. This approach is based on a combination of the Monte Carlo Simulation method and an iterative algorithm developed for calculating structural performance function. The damaged ductile frame structure is simulated with a lumped plasticity model, while the singularity of the structural stiffness matrix is adopted as a reasonable failure criterion for structures under static loading conditions. A performance function is established based on the virtual work principle, critical collapse mechanism criterion and a construction system. An iterative procedure is developed to solve the performance function where the interaction between the axial force and the strength of the end springs is considered in the calculation of the minimum internal virtual work. A flowchart based on a combination of the developed procedure and the Monte Carlo Simulation method (MCS) is presented for the reliability assessment of damaged structures under static loading conditions. In order to consider the dynamic effects induced by the sudden loss of a column in a close-in detonation, the method for the reliability assessment of the damaged ductile frame against progressive collapse under static loading conditions is further developed. The safety of the frame structure is evaluated based on two aspects: (1) the flexural response and (2) the shear response of the structure. Two performance functions are formed for structural flexural response to consider the structural collapse due to the lack of strength or deformation capacity of the structural weakest collapse mechanism. A third performance function is constructed to consider shear response. Since any of the above three performance functions less than zero will lead to structure progressive collapse, a global performance function is calculated by taking the minimum of these functions.
DRNTU::Engineering::Civil engineering::Structures and design