Analysis of Infilled Frames Subject to Racking with Design Recommendations

Mr. Gavin Orr's letter (March 77) has brought an approving response from several readers but a general suggestion that times change and that however good the old methods of training were, we cannot put the clock back. Mr. F. G. Alchin, for instance, says : Mr. Gavin Orr's recently published account of pre-war structural steelwork training I found very nostalgic as it coincides with my having enjoyed a similar experience. As this commenced some 50 years ago there cannot be many of us left, at least actively employed, but one can only concur with every comment he makes. Verulam

A general method using the theory of thin walled structures is given for determining the natural frequencies and mode shape of core wall structures having closed or open section, subjected to torsion and bending using a finite element approach. Consistent mass matrices related to torsion and bi-moment effects have been derived using shape functions corresponding to (a) the static deflection configuration and (b) an assumed polynomial deflection configuration. The stiffness matrix developed on the basis of the proposed theory includes warping deformations and its use with the finite element method enables the possible changes in the storey segments to be fully represented, such as the thickness of the wall and the cross-sectional characteristics. D.V. Mallick and R. Dungar

Professor A. W. Hendry (F): In my department in the University of Edinburgh we have for many years been engaged on research work on unreinforced masonry. For the most part this has been concerned with clay brickwork sponsored by the British Ceramic Research Association and BDA but a limited amount of work has been carried out on concrete blockwork, particularly using lightweight aggregate blocks. Some of the results may be of interest in supplementing the work reported in the present paper.