Design Of Skeletal Structures Research Articles

The stability of semi-rigid skeletal structures accounting for shear deformations

The analysis and design of skeletal structures is greatly influenced by the behaviour of beam-to-column connections, where patented designs have led to a wide range of types with differing structural quantities. The behaviour of beam-to-column connections plays an important role in the analysis and design of framed structures. This paper presents an overview of the influence of connection behaviour on structural stability, in the in-plane (bending) mode of sway. A computer-based method is presented for geometrically nonlinear plane frames with semi-rigid connections accounting for shear deformations. The analytical procedure employs transcendental modified stability functions to model the effect of axial force on the stiffness of members. The member stiffness matrix were found. The critical load has been searched as a suitable load parameter for the loss of stability of the system. Several examples are presented to demonstrate the validity of the analysis procedure. The method is readily implemented on a computer using matrix structural analysis techniques and is applicable for the efficient nonlinear analysis of frameworks. Combined with a parametric column effective length study, connection and frame stiffness are used to propose a method for the analysis of semi-rigid frames where column effective lengths are greatly reduced and second order (deflection induced) bending moments in the column may be distributed via the connectors to the beams, leading to significant economies.

A biogeography-based optimization for optimum discrete design of skeletal structures

This article presents a modified biogeography-based optimization (MBBO) algorithm for optimum design of skeletal structures with discrete variables. The main idea of the biogeography-based optimization (BBO) algorithm is based on the science of biogeography, in which each habitat is a possible solution for the optimization problem in the search space. This algorithm consists of two main operators: migration and mutation. The migration operator helps the habitats to exploit the search space, while the mutation operator guides habitats to escape from the local optimum. To enhance the performance of the standard algorithm, some modifications are made and an MBBO algorithm is presented. The performance of the MBBO algorithm is evaluated by optimizing five benchmark design examples, and the obtained results are compared with other methods in the literature. The numerical results demonstrate that the MBBO algorithm is able to show very competitive results and has merits in finding optimum designs.

A revised discrete Lagrangian-based search algorithm for the optimal design of skeletal structures using available sections

Issues relating to the application of the discrete Lagrangian method (DLM) to the discrete sizing optimal design of skeletal structures are addressed. The resultant structure, whether truss or rigid frame, is subjected to stress and displacement constraints under multiple load cases. The members’ sections are selected from an available set of profiles. A table that contains sectional properties for all the available profiles is used directly in structural optimization. Each profile in the table is assigned by a unique profile number, which is used as the integer design variable for each of the structural members. It is proposed that we use a revised DLM search algorithm with static weighting to design trusses and rigid frames for minimum weight. Five examples are used to demonstrate the feasibility of the method. It is shown that, for monotonic as well as nonmonotonic constraint functions, the DLM is effective and robust for the discrete sizing design of skeletal structures.

OPTIMAL DESIGN OF SKELETAL STRUCTURES UNDER ELASTIC AND PLASTIC DESIGN CRITERIA

OPTIMAL DESIGN OF SKELETAL STRUCTURES UNDER ELASTIC AND PLASTIC DESIGN CRITERIA

Plastic Design under Multiple Loads

A mathematical model and a solution algorithm are developed for the rigid-plastic optimal design of skeletal structures under multiple loading conditions. Iterative linear programming techniques are applied to account for nonlinear variations in element plastic capacities under combined stress states as the structural design is modified to meet specified strength requirements. The design concepts are illustrated for two framework examples.

Reply: Toward automated elastic design of skeletal structures using computer graphics

Reply: Toward automated elastic design of skeletal structures using computer graphics

Discussion: Toward automated elastic design of skeletal structures using computer graphics

Discussion: Toward automated elastic design of skeletal structures using computer graphics

Toward automated elastic design of skeletal structures using computer graphics

The purpose of this paper is to demonstrate that the introduction of computer graphics to the field of automated structural design alleviates many of the problems inherent in the use of high speed digital computers in structural design by permitting an interaction between the designer and the design program.This interaction provides significant advantages over conventional computer-aided design. The input of data is facilitated, and the designer can verify that the data are correct by having them displayed on the screen. The designer is able to control the optimization while it is in progress. By examining the results after each iterative cycle, he is able to implement design decisions and terminate the design when satisfactory convergence is achieved. Foremost, the designer is given an intuitive knowledge of the structural problem he is dealing with because he is able to examine in one session with the computer, the effect of various structural parameters, such as column spacing and displacement constraints.

Gradient Methods in Optimum Structural Design

The paper presents two new gradient-based methods for the optimum design of skeletal structures. Both methods can accommodate stress, member size, and displacement constraints and can converge to an optimum that is either a vertex or a nonvertex of the feasible region. The Method of Incomplete Gradients uses the dominant terms of the active constraint gradients and converges rapidly for normal acting structures. The Method of Auxiliary Gradients augments active constraints with auxiliary constraints when necessary, uses the full gradients, and converges rapidily for structures with normal or hybrid action. The two methods, together with the Stress Ratio Method, are arranged into an efficient automatic design technique that can start at any initial design. The technique is applied to the design of two rigid frames having displacement constraints and multiple loadings.