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Concerns have been raised over the presence of concrete slab and resulting composite action in jeopardising the concept of strong column and weak beam seismic design. This comprehensive finite element analysis (FEA) aims to study the effect of the degree of composite action and other two parameters; namely, size and location of the web opening, on the performance of steelconcrete composite extended end-plate RWS connections subjected to cyclic loading. It is apparent that the degree of composite action of RWS connections is an important factor in their seismic-resistant design. In particular, the low degree of composite action in RWS connections can result in the mitigation of the bottom flange fracture damage and the crushing and cracking of the concrete slab. It is concluded that extended end-plate RWS connections can be used in retrofitting existing and in new buildings in seismic areas.

Due to the concerns regarding the effects of the composite action on the seismic performance of beam‐to‐column connections leading to premature brittle fracture of the beam bottom flange, this paper introduces a comprehensive finite element (FE) analysis studying the effect of the degree of composite action to the performance of the bolted extended end‐plate (BEEP) RWS connections subjected to cyclic loads. Circular web openings with diameter equal to 0.8 of the beam's depth and two different parameters, namely the distance from the face of the column, S, and the degree of composite action, are investigated. Based on the results, it is confirmed that the degree of composite action of RWS connections is an important factor in seismic‐resistant design. It is concluded that the low degree of composite action with the use of a structural fuse, such as an RWS connection with localised beam web opening, can potentially avoid bottom flange fracture damage. It is found that composite RWS connections can also be employed to improve the seismic performance on steel structures.

This paper presents an experimental study on demountable steel-concrete composite reduced web section (RWS) connections for use in seismic areas. Four composite connection specimens were subjected to sagging and hogging moments to investigate the performance of RWS connections under reversible actions. For such purpose, a single opening was made near the beam-column joint. Focus was made on the effects of perforation location and composite beam-slab action induced by bolted shear studs within the protected zone. Results indicate that employing RWS connections for seismic retrofit is a viable solution capable of achieving a performance similar to that observed for RWS connections in new buildings. Notably, a Vierendeel mechanism is generated, hence allowing for plasticity development in the beam, All RWS connections were capable of achieving an interstory drift larger than 4%, thereby complying with the performance targets set by ANSI/AISC 358 − 16, ANSI/AISC 341 − 16 and EC8. Moreover, deformation of the stubs was slight enough to allow for dissasemblage after the tests, indicating that the proposed solution could enable for reuse and retrofit after earthquakes.