An investigation is described into the effect of various combinations of the normal modes of vibration of cantilever shear wall structures on the maximum shears at flexural capacity. It is shown that the base shear can be much higher than would be derived by assuming a normal code lateral load distribution of sufficient magnitude to cause flexural yielding. The results of elastic normal mode response spectrum analyses of a 10-storey building considering several structural variables are presented in terms
of envelope values of the ratio of maximum base shear at flexural
capacity to that assuming a code lateral load distribution. The same effect is investigated with a series of step-by-step numerical integration dynamic analyses of cantilever wall structures responding inelastically to a range of earthquakes. On the basis of the results suggestions are made for the shear design of cantilever walls.

The design, construction and testing of two large reinforced concrete beam-column assemblies, representing an interior and an exterior joint, are described. Member details were based on an actual frame building designed by the M.W.D. Extensive results are presented which indicate very satisfactory behaviour particularly in the joint region. Hinges formed in the beams in all cases, and stable behaviour was obtained at displacement ductility factors of up to 6 and 8 for the interior and exterior test units respectively. Results are assessed in terms of design assumptions, and tentative design recommendations are made.

Seismic design of bridges

This paper provides background information on the provisions of the proposed New Zealand Standard Code of Practice for General Structural Design and Design Loadings relating to the separation of non-structural elements from the structure, and the separation of buildings from adjacent buildings. The degree of protection afforded by these provisions is indicated for various levels of earthquake attack, and designers are warned of the implications of possible non-structural damage under severe seismic loading.

The paper describes the testing of two reinforced concrete beam-column joint units tested under incremented-static cyclic
 loading. The full size test units were based upon an interior beam-column joint of a four-storey 
framed building designed to the current NZ loading code and represent 
refinements on two previously tested conventional joints of similar dimensions. One unit differed from common practice by having a post-tensioned beam stressed to balance the floor dead load of the prototype structure whilst the second unit was detailed with haunched beams. Hinge formation occurred in the beams and stable hysteretic behaviour was obtained up to displacement ductilities of 10 for the prestressed unit and 6 for the haunched unit. The test results are analysed in terms of the draft NZ design code, DZ 3101, and the ACI Recommendations for beam-column joint design.