Stiffness Optimization Of Large-span Roof Structures Under Wind Loads By The Quantum-behaved Particle Swarm Optimization Algorithm

As the society advances, varieties of large-span roof structures have increasinglysprung up. Its wind-resistant optimum design can effectively improve the mechanicalperformance and save construction costs. However, researches on the wind-resistantoptimization concentrates on high-rise buildings, but seldom on roof structures. Withdesirable versatility, a wind resistant systematic method for large-span roof structuresbased on Quantum-behaved Particle Swarm Optimization (QPSO), which is a noveland effective stochastic intelligent algorithm and barely employed to civil engineering,is established. The detail works go as follows:1. By introducing the coordinate factor for constraint violation, a well-performeddynamic penalty function expression is newly constructed. And through its integrationinto the algorithm QPSO known as an unconstrained algorithm, an algorithmDPQPSO (Dynamic-Penalty-based QPSO) is proposed to deal with constrainedoptimization problems, such as wind-resistant optimization of simple roof structures.The corresponding universal code has been written.2. By modifying self-adaptive penalty function expression, the algorithmSPQPSO (Self-Adaptive-Penalty-based QPSO), are proposed to deal withwind-resistant optimization for complex roof structures. The universal computationcode has also been accomplished.3. Based on the theories of CQC (Complete Quadratic Combination) method andLRC (Load Response Correlation) method, two programs for computing windinduced response (such as displacements and stresses) and equivalent static windloads (ESWLs) are written respectively, taking into consideration of modal couplingeffect and cross terms of wind force spectrum. Then, wind-induced responsecharacteristics of large-span roof structures, such as statistical characteristics, spectralcharacteristics and contributions of background and resonant components, arediscussed. Distributions of ESWLs and mean wind load on the roof are compared, andcontributions of each mode are investigated.4. Through discrete variable handling, wind-resistant optimization of a portalframe with variable cross-sections is conducted by the algorithm of DPQPSO. Windload on the structure is firstly obtained from the wind tunnel database of TokyoInstitute of Technology, Japan. Design variables are then determined according to the design standard. Finally, statistical results of optimization and mechanicalcharacteristics of the optimal structure are analyzed.5. Through established ESWLs, wind-resistant optimal design of a dry coal shedin a power plant, which is a double-layer cylindrical reticulated shell, is implementedthrough the SPQPSO algorithm. Additional constraint coupled with the objectivefunction is found to accelerate the convergence of optimal design. The constructuednormalized mapping coordinate system can help the better knowledge of the searchmechanism.