Optimal seismic-resistant design of a planar steel frame (original) (raw)

Seismic and Robustness Design of Steel Frame Buildings

Key Engineering Materials

In this paper, a design procedure that combines both progressive collapse design under column removal scenario and capacity design to produce a hierarchy of design strengths is presented. The procedure develops in the context of the European Standards, using the classification of European steel sections and considering the seismic design features. Three-dimensional models of typical multi-storey steel frame buildings are employed in numerical analysis. The design for progressive collapse is carried out with three types of analysis, namely linear static, nonlinear static and nonlinear dynamic. Since the behaviour following sudden column loss is likely to be inelastic and possibly implicate catenary effects, both geometric and material nonlinearities are considered. The influence of the fundamental parameters involved in seismic and robustness design is finally investigated.

Optimum Design of Steel Moment Resisting Frames Subjected to Seismic Excitation

The main aim of this project is to develop an interior penalty function (IPF) based algorithm to multi-storey steel frames for minimum weight of frames. The frames are intended for resisting lateral sway due to seismic loading along with gravity forces. Many structural systems are used for resisting seismic (lateral) forces; however steel moment resisting frames (MRF) are considered for the present work. The design methodology incorporates codal provisions of IS 800-2007, thereby obtains the frames with optimum weight for in-plane moments with lateral support of beam elements. Strength and buckling criteria are considered as behaviour constraints along with side constraints in formulating optimization problem. A computer program is developed that uses an interior penalty function (IPF) for weight minimization of two-dimensional moment resisting steel framed structures. The program uses MATLAB, performs one dimensional search, and structural design in an iterative procedure. The desi...

Optimal design of steel frames subject to gravity and seismic codes' prescribed lateral forces

Structural Optimization

Allowable stress design of two-dimensional braced and unbraced steel frames based on AISC specifications subject to gravity and seismic lateral forces is formulated as a structural optimization problem. The nonlinear constrained minimization algorithm employed is the feasible directions method. The objective function is the weight of the structure, and behaviour constraints include combined bending and axial stress, shear stress, buckling, slenderness, and drift. Cross-sectional areas are used as design variables. The anylsis is performed using stiffness formulation of the finite element analysis method. Equivalent static force and response spectrum analysis methods of seismic codes are considered. Based on the suggested methodology, the computer program OPTEQ has been developed. Examples are presented to illustrate the capability of the optimal design approach in comparative study of various types of frames subjected to gravity loads and seismic forces according to a typical code.

Structural optimization procedures under seismic loading

The purpose of this work is twofold. The first objective is to present robust and efficient methodologies for performing structural optimum design of steel frames under seismic loading with deterministic and/or probabilistic constraints. The second objective is to consider the impact of future earthquakes on the design adopted using an estimation of the life cycle cost of the structure.

Issues In The Design Of Steel Structures For Seismic Loading

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.

ANALYSIS OF A STEEL BUILDING AGAINST EARTHQUAKE LOADS

In the world the most widely used material for building construction is Steel. Steel is playing an important role as a building material with combination of concrete as Reinforced cement concrete in the modern days. With the invention of steel as a building material revolution in high rise construction has been started. The genetic properties of steel like strength, toughness, ductility and other appropriate properties made the engineers to select as a building material and also made the characteristics that are useful for seisimic design. As a designer engineer he should know the application of the steel design rules which is given in code books for the seismic applications. The seismic design of building frame in this paper is based on IS 1893-2002 and codal provisions are considered for the design is IS 800-2007 and STAAD Pro is used for analysis. The present work aims to analyze and design of a multi-bay and multi storied(G+5) steel structure for earthquake forces following IS 1893-2002 and design as per IS 800-2007.The selection of arbitrary sections have been done following a standard procedure and corrections are done accordingly for earthquake loads. The two methods that have been used for analysis are Equivalent static load method and Response Spectrum method. The frame has also been further checked for P-∆ analysis and required corrections has been done and final results are documented. Finally, the design of connection of an interior joint and an exterior joint of the frame have been done and the calculations have been shown and figures are drawn. The cost efficiency of both the methods have been compared.

Seismic Design of Steel Moment-Resisting Frame Structures Using Multiobjective Optimization

Earthquake Spectra, 2005

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...

Robust Optimization of the Steel Single Story Frame

Acta Polytechnica Hungarica

In contemporary design practices, building structures are expected to not only meet safety requirements but also be optimized. However, optimal designs can be highly sensitive to random variations in model parameters and external actions. Solutions that appear effective under nominal conditions may prove inadequate when parameter randomness is considered. To address this challenge, the concept of robust optimization has been introduced, which extends deterministic optimization formulations to incorporate the random variability of parameter values. In this study, we demonstrate the applicability of robust optimization in the design of building structures using a simple orthogonal frame as an example. The static-strength analysis is conducted based on the displacement method, utilizing second-order theory. To assess the safety level of the steel frame, a preliminary evaluation is performed by determining the reliability index and failure probability using the Monte Carlo Method. Robust optimization is then employed, leveraging the second-order response surface. Experimental designs are generated following an optimal Latin hypercube plan. The proposal of a mathematical-numerical algorithm for solving the optimization problem while considering the random nature of design parameters constitutes the innovative aspect of this research.