Buckling length of reinforced concrete columns in non-sway constructions

The paper presents a comparison of methods of determining the buckling length of reinforced concrete columns in non-sway frames. The comparison was made on the basis of guidelines issued by Poland some EU countries, USA and India. Differences in approaches and values of buckling length coefficients of columns calculated according to these guidelines are shown. An example of the calculation of column buckling length coefficients on selected multi-span, multi-storey non-sway frames is given.

Influence of joint rigidity on the elastic buckling load of sway and non-sway steel frames

Much work has been conducted in the past on the influence of the rigidity of structural joints on the behavior of steel frames. Buckling of a column is fundamental to the design of load bearing structures mainly when the analysis of such frames takes into account the effect of the connection flexibility. The present work deals with such an effect on the elastic buckling load of plane steel frames. The proposed model consists in the development of comprehensive approach taking into account, the effects of the joint rigidity, the elastic buckling load for both sway and non-sway frames. Only one element is required over the length of the element to model stability, which let to solve practical problem with little computational effort. Some practical formulas for determining critical load for plane steel frames are then presented. The elastic buckling load is found to be strongly affected by semi-rigid joints and reveals that the proposed model is computationally very efficient with the expressions presented being general.

AN ENHANCED IMPERIALIST COMPETITIVE ALGORITHM FOR OPTIMUM DESIGN OF STEEL FRAMES

Development of efficient and robust optimization methods for structural design is one of the most active research fields in structural engineering. Imperialist Competitive Algorithm (ICA) is one of the recent meta-heuristic algorithms proposed to solve optimization problems. In this paper, an Enhanced Imperialist Competitive Algorithm (EICA) is proposed which increases the search space and enables the ICA algorithm to escape from local optima in a fast time. In this algorithm added value is given to a slightly unfeasible solution, based on its distance from the relative imperialist. The performance of the proposed EICA algorithm in optimum design of side sway frames is investigated by comparing the EICA optimum designs of two benchmark side sway frames with the best designs obtained using a number of other meta-heuristic solutions. Results indicate that, in terms of both the design quality and the solution speed, EICA compares favorably with a number of other meta-heuristic optimizers, including the basic ICA.

Story-Based Stability Analysis for Evaluating Story Buckling Load of Frames

This paper presents a kind of optimum modeling method for evaluating system buckling load of plane sway frames, based on the research of the different correction coefficient β. The buckling load of plane sway frames was calculated by using the optimized method, and the results were compared with those of the ANSYS. It is verified that the simplicity, accuracy and applicability of the method.