How to Optimize Tall Steel Building Frameworks

Abstract

Due to the complex nature of a modem tall building consisting of thousands of structural members, the traditional trial-and-error design method is generally highly iterative and time consuming. This c'.'apter presents an optimal sizing technique for the design of practical tall steel building frameworks. A computer-based technique is developed to formalize the numeric tasks of the analysis-design cycle and produce minimum cost design of tall steel frameworks of given topology under static gravity and lateral loadings. Most economical member sizes are automatically selected from databases of commercial standard steel sections, and service lateral drift, ultimate member strength, and discrete sizing constraints are simultaneously satisfied in accordance with building code and constructability requirements.The design optimization approach is based on an Optimality Criteria method, which is well suited for large-scale tall building frameworks. By exploiting the fact that member force distributions are relatively insensitive to changes in member sizes for building frameworks, the design optimization technique generally converges rapidly in a few cycles. A full-scale SO-story building example is presented to illustrate the applicability, efficiency, and practicality of the automatic optimal sizing technique.

Time-domain dynamic drift optimisation of tall buildings subject to stochastic wind excitation

“…Rapid and steady solution convergence is often found since the energy-based formulation of the drift design constraints has exploited to advantage the peculiar behaviour of building structures, which globally behave as a vertical cantilever such that the internal force distributions of the structures are somewhat insensitive to moderate changes in element sizes (Chan, 1997(Chan, , 2001. Further details of the rigorously derived OC method can be referred to Chan (1997Chan ( , 2001.…”

“…Due to the scale and complexity of these structures, a computer-based automated structural optimisation technique is always desired so as to provide engineers an efficient design tool for searching the best design solution against static and dynamic loads. The research on structural optimisation of building structures under static loads has been ongoing for several decades (Arora & Wang, 2005;Chan, 1997Chan, , 2001Grierson, Gong, & Xu, 2006;Kirsch, 1993). However, limited research has been conducted on developing computer-based methods for structural optimisation of buildings subject to spatiotemporally varying dynamic wind loads.…”

Optimal seismic performance-based design of reinforced concrete buildings using nonlinear pushover analysis

“…To speed up the convergence of the OC process, it is important to begin with a reasonably good starting design. One effective scaling approach was proposed by Chan [17]. In such an approach, the design optimization with a single drift constraint is first considered and a simple "closed form" solution for the problem is derived analytically and exploited as an initial preprocessor for the iterative OC process.…”

“…Chan [17,18] developed an efficient computer-based optimization technique for lateral stiffness design of tall buildings. The optimization technique, developed on the basis of a rigorously derived Optimality Criteria (OC) approach, is capable of optimizing large-scale tall steel and/or reinforced concrete buildings subject to multiple static wind drift and dynamic wind-induced vibration design constraints.…”

Integrated aerodynamic load determination and stiffness design optimization of tall buildings

“…Although automated optimization techniques are now made available for optimizing the lateral stiffness of tall building structures subject to static drift and dynamic frequency constraints (Chan, 1997(Chan, , 1998(Chan, , 2001, the stiffness design optimization is normally carried out with a fixed set of wind loading conditions. Since the optimization techniques are generally applied without a proper update of the ESWLs, the stiffness enhancement achieved by such optimization techniques may likely result in an over-conservative design in which the structural load is probably overestimated.…”