This paper describes an experimental study on double-angle shear connections with a narrow outstanding leg width from 31 to 37 mm. When connection angles are welded to a supporting column with a face width less than 152 mm, a common practice is either to weld the angles to the column by flare bevel groove welds or shorten the outstanding legs to accommodate fillet welds. This practice reduces the rotational capacity of the connections; and therefore confirmation of this practice is required. Three groups, comprising 12 full-scale connection specimens, were tested. Each group consisted of four specimens having three, four, five, and six bolts, respectively. Group A used 9.5 mm thick angles and fillet welds, group B used 6.4 mm thick angles and fillet welds, and group C used 9.5 mm thick angles and flare bevel groove welds. The test results demonstrated that both rotational and shear capacities of the connections are satisfactory when either of the two details are used.

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For the determination of the dynamic response of a structural
system to earthquake ground motion the mode superposition technique offers an alternative approach to the well established direct integration method. Whereas the principle of modal superposition is encountered commonly in elastic analyses, the response of a yielding structure is predicted almost universally by direct integration of the
equation of motion. In this paper the principles of modal superposition are extended into the post-elastic domain. Among the advantages which accrue from the modal based transformation are a potential reduction in the number of dynamic degrees-of-freedom considered in the solution, and a new insight into the structure response provided by the instantaneous dynamic properties of the structure.

No abstract

The necessity for framed structures to be capable of dissipating significant amounts of energy inelastically under severe earthquake excitation is generally acknowledged. Bridge structures differ from buildings in their seismic lateral resistance mechanism in so far as they generally possess a small number of clearly identifiable potential zones in which plastic yield can occur and consequently tend to be amenable to postelastic studies. This paper presents the application of an analysis technique in which the response time history of a bridge structure, treated as a three-dimensional frame, is determined by direct integration of the equations of motion with allowances incorporated for inelastic member behavior. Aspects studied include the differences in responses predicted using a nonlinear three-dimensional model rather than a planar frame idealization and the effect of unequal span lengths or torsional vibrations.