Optimal design of steel frames subject to gravity and seismic codes' prescribed lateral forces (original) (raw)
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High rise structures Energy absorption P-∆ effect Earthquake forces mandate the absorption of energy imparted by it on the structures and steel is best suited for this. Multi-storey buildings are generally constructed in steel as framed structures. A ductile frame can undergo important inelastic deformations, localized in the neighborhood of sections with maximum bending moment. Considerable care is also needed in the design of steel structures to check failures due to instability and brittle fracture to ensure the development of full ductility and energy dissipation capacity under earthquake loading. Load and Resistant Factor Design (LRFD) is a design practice globally adopted to take care of the inelastic behavior of steel. Good workmanship is also an essential requirement in the construction of steel structures which has to resist severe earthquake forces. The paper highlights the issues involved in the design of steel buildings for seismic forces as well as the basic requirements of material characteristics.
Seismic Design of Steel Moment-Resisting Frame Structures Using Multiobjective Optimization
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Design of seismic-resistant civil structural systems necessitates a balanced minimization of two general conflicting objective functions: the short-term construction investment and the long-term seismic risk. Many of the existing seismic design optimization procedures use single objectives of either the traditional minimum material usage (weight or cost) or the recent minimum expected life-cycle cost, while imposing constraints from relevant code specifications as well as additional seismic performance requirements. The resulting single optimized structural design may not always perform satisfactorily in terms of other important but competing merit objectives; the designer's individual risk-taking preference is not explicitly integrated into the design process. This paper presents a practical and general framework for design optimization of code-compliant seismic-resistant structures. Multiple objective functions, which reflect material usage, initial construction expenses, degr...
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Engineering with Computers, 2020
The main purpose of this study is to respond to an important question in the field of structural engineering: is the seismic collapse capacity of optimally designed concentrically steel braced frames acceptable or not? The present work includes two phases: performance-based design optimization and seismic collapse safety assessment. In the first phase, three natureinspired metaheuristic algorithms, namely improved fireworks algorithm, center of mass optimization, and enhanced colliding-bodies optimization are employed to carry out the optimization task. In the second phase, seismic collapse capacity of the optimally designed concentrically steel braced frames is evaluated by performing incremental dynamic analysis and generating fragility curves. Two design examples of 5-and 10-story concentrically steel braced frames with two different topologies of braces are presented. The numerical results indicate that the center of mass optimization algorithm outperforms the other algorithms. However, all of the optimal designs found by all algorithms are of acceptable seismic collapse safety.