Earthquake reconnaissance has identified failure of reinforced concrete columnsas a primary cause of collapse of older existing reinforced concrete buildingframes during earthquakes. Apparent column failure, however, does not always result in building collapse. A study of columns tested in the laboratory examinesloss of lateral and vertical load capacities. Correlations with geometric, materials, and loading characteristics are identified.

The seismic design requirements in the Building Standard Law of Japan were revised in June 2000 toward a performance-based design framework. The performance objectives are (a) life safety and (b) damage control of a building at two corresponding levels of earthquake motions. The design earthquake motion is defined in terms of acceleration response spectrum at engineering bedrock. The amplification of ground motion by surface geology and the soil-structure interaction must be taken into consideration. The response is examined by so-called capacity spectrum method by comparing the linearly elastic demand spectrum of design earthquake motions and the capacity curve of an equivalent single-degree-of-freedom (ESDF) system. The structure as designed is reduced to an ESDF system using a nonlinear static analysis under monotonically increasing horizontal forces. Equivalent damping is used to modify the demand spectrum taking into account the energy dissipation capacity of a structure at the prescribed limit states.

With few exceptions, code provisions relevant to torsional phenomena in buildings subjected to seismic effects, are based on elastic structural behaviour. The key parameter is stiffness eccentricity. The appropriateness of this approach to the design of systems expected to respond in a ductile manner is questioned. The degree ofrestraint with respect to system twist, strength eccentricity and the pattern of element yield displacements are considered to be more important parameters. For the purposes ofseismic design, bi-linear force-displacement approximations of the elasto-plastic behaviour of reinforced concrete systems and their constituent elements, are considered to be adequate. Strategies aiming at the elimination of undesirable effects of torsional phenomena in ductile systems are addressed. The findings of this study are based on a re-definition of some common terms of structural engineering, such stiffness, yield displacement and displacement ductility relationships. Contradictions withcorresponding terms applicable to elastic systems are demonstrated. The introduction ofthese features, relevant to bilinear modelling of reinforced concrete elements, precedes the examination of the designer’s options for the control of earthquake-induced displacement demands resulting in system translations and twist.

The mission of most AC1 technical committees is to develop and report information and a large number of missions include develop and maintain standards for use in design, construction, maintenance or other practice-related application. In general, the reports technical committees develop become prime sources of information in their assigned area. The objective of this paper is to document the formation of the committee and the development of the first report of AC1 352 Joints and Connections in Monolithic Concrete Structures published in 1976. The reports of AC1 352 have had considerable impact on the design and construction of concrete structures. The activities of AC1 352 provide a case study in the role of a committee in providing a vital link between research and practice. It seemed appropriate to discuss the work of AC1 352 at the Uzumeri Syposium because Mike Uzumeri served as a member of the committee. His research on the behavior of beam-column joints was an important part of the data on which the first report of AC1 352 was based.

This paper describes an investigation into the seismic performance of a six storey moment resisting frame structure located in Vancouver and designed and detailed in accordance with the seismic provisions of the National Building Code of Canada (1995). Both pushover and dynamic analyses are conducted using an inelastic model of the structure as designed and detailed. The structural performance of frames designed with different ductility capacities is evaluated using interstorey drift and member curvature ductility response as performance measures. All frames studied are expected to perform at an operational level when subjected to design level seismic excitations and to meet life safe performance criteria at excitations of twice the design level.