A. Jennings

Algorithm 570: LOPSI: A Simultaneous Iteration Method for Real Matrices [F2]

Received 12 December 1977, 12 June 1979, and 14 April 1980. Permmsion to copy without fee all or part of thin material is granted provided that the copras are not made or distributed for direct commercial advantage, the ACM copymght notice and the title of the publication and its date appear, and notice is gwen that copying is by permission of the Association for Computmg Machinery. To copy otherwise, or to republmh, requires a fee and/or specific perralSSlOn Authors addresses: W. J. Stewart, Department of Computer Science, North Carolina State Univero sity, P.O. Box 5972, Raleigh, NC 27650; A. Jennings, Department of Civil Engineering, Queens University, Belfast, BT7 1NN Northern Ireland

Deflection theory analysis of different cable profiles for suspension bridges

Abstract Modifications are developed which allow deflection theory to be used to analyse the structural behaviour of suspension bridges in which the deck is supported by two or more cables having different profiles. Static deflections due to concentrated and distributed loads are considered. It is ascertained that increased stiffness can be obtained by using such configurations.

On the identification of yield-line collapse mechanisms

A theorem is proved which is useful in establishing topologies of yield-line mechanisms likely to cause collapse of an important class of slabs (or plates). It is also shown, through another theorem, that the search amongst concave mechanisms for the most probable one to cause collapse can use a uniqueness property which ensures that the function to be searched has no false maxima.

Computer-assisted generation of yield-line patterns for uniformly loaded isotropic slabs using an optimisation strategy

The method of Munro and Da Fonseca uses a fixed, arbitrary mesh of potential yield-lines to predict the collapse load of a slab or plate. This paper describes an optimisation procedure for adjusting the mesh to provide a safer estimate of the collapse load. The paper is mainly devoted to practical examples illustrating the application of the technique.

Implementation of simultaneous iteration for vibration analysis

Abstract There are several ways in which simultaneous iteration may be carried out for symmetric eigen value problems. This paper discusses the use of these for finding the first few modes of vibration of a large undamped structural system by computer. Two alternative methods are advocated. The first is a simple method adopting an approximate interaction analysis. The second achieves a controlled rate of convergence and improved efficiency by using a Sturm sequence procedure together with Chebyshev acceleration of the simultaneous iteration and accurate eigensolution of the interaction matrix.

Automatic plastic design of frames

Abstract A modified simplex technique is described for the optimal plastic design of plane frames subject to one or more loading cases using a minimum weight criteria for the selection of relative member sizes. The initial tableau is based on the lower bound (equilibrium) method and can be constructed automatically from geometrical and loop information describing the structure and also loading data. The small tableau size makes the method efficient and hence feasible to use in interactive design programs.

Focusing on communication skills in engineering education

ABSTRACT The development of communication skills is now considered to be a desirable feature of engineering undergraduate courses. However, to convert what is desirable into reality requires finding space in an already overcrowded syllabus. The solution proposed in this paper is to use the development of communication skills as the focus for active learning assignments relevant to the particular engineering discipline being studied. A ‘Learning from Disasters˚s exercise and two mock public inquiries recently held in the Civil Engineering Deparment at Queens University, Belfast (QUB) are illustrations of how this may be achieved and of the benefits to be gained.

A computerised method for rigid-plastic yield-line analysis of slabs

Abstract A semi-automatic method is presented for the rigid-plastic yield-line analysis of slabs to predict the mechanisms which are most likely to cause collapse. The computational technique adopted uses linear programming to evaluate the Munro and Da Fonseca solution for any given trial element geometry and non-linear optimisation techniques to investigate the effect of adjusting the geometry. Linearized constraint equations are developed analytically and used with the conjugate gradient method in order to overcome problems due to the existence of discontinuities in slope of the optimising function. Computation procedures are given and an algorithm for this is described with examples.

Optimal plastic design of frames with tapered members

Abstract The different formulations for minimum weight plastic design of structural frames are discussed with reference to the inclusion of tapered members in the optimisation process. An equilibrium method is presented in more detail showing how pin-joints can be taken into account and plastic moment constraints imposed. A technique for optimising over several loading cases and a procedure for plastic analysis are both specified. Some comparisons are also made of tableau sizes, computing times and weight savings for three types of frame geometry and loading.

Classification and Comparison of LP Formulations for the Plastic Design of Frames

The investigation of the design of structural frames to meet a collapse criterion according to rigid-plastic theory leads, under conventional assumptions, to a mathematical model requiring solution by linear programming (LP). However, there are many such different formulations in the literature. The main purpose of this paper is to classify all such methods into four types, each with an associated dual formulation. Relationships between the types of method are also presented and there is a brief discussion of their computational efficiencies and ease of automation.