Slender reinforced concrete shear walls with high-strength concrete boundary elements

Reinforced concrete structural walls are commonly used for resisting lateral forces in buildings. Owing to the advancements in the field of concrete materials over the past few decades, concrete mixes of high compressive strength, commonly referred to as high-strength concrete (HSC), have been developed. In this study, the effects of strategic placement of HSC on the performance of slender walls were examined. The finite-element model of a conventional normal-strength concrete (NSC) prototype wall was validated using test data available in extant studies. HSC was incorporated in the boundary elements of the wall to compare its performance with that of the conventional wall at different axial loads. Potential reductions in the reinforcement area and size of the boundary elements were investigated. The HSC wall exhibited improved strength and stiffness, and thereby, allowed reduction in the longitudinal reinforcement area and size of the boundary elements for the same strength of the conventional wall. Cold joints resulting from dissimilar concrete pours in the web and boundary elements of the HSC wall were modeled and their impact on behavior of the wall was examined.

Experimental testing of RC shear wall seismic retrofit using selective weakening,self-centering and Ultra High performance concrete

Traditional retrofit methods often focus on increasing the structure’s strength,stiffness,or both.This may in-crease seismic demand on the structure and could lead to irreparable damage during a seismic event.This paper presents a retrofit method,integrating concepts of selective weakening and self-centering(rocking)to achieve low seismic damage for non-code compliant reinforced concrete shear walls.The proposed method involves con-verting traditional cast-in-place concrete shear walls into rocking walls,which helps to lower the shear demand,while allowing re-centering.Two large-scale lateral load tests were performed to validate the retrofit concept on a concrete shear wall designed according to pre-1970s standards.The design parameters investigated were amount of energy dissipating reinforcements and confinement enhancement.Two different methods using Ultra High Performance Concrete(UHPC)were investigated to provide additional confinement to boundary elements of older shear walls.Observations from the tests showed minimized damage and enhanced recentering in the retrofitted wall specimens.Use of UHPC in the boundary elements of the retrofitted walls provided additional confinement and reduced damage in the rocking corners.

Behavior and modeling of tessellated shear walls in a structural frame system

This paper studies the behavior of a reinforced concrete(RC)structural frame employing a tessellated structuralarchitectural(TeSA)shear wall as the lateral-load resisting element.TeSA walls are made of interlocking modules(tiles)that provide easier repairability and replaceability.A nonlinearfinite element model of a TeSA wall with tiles interlocking in one direction(1-D interlocking)is validated using test data.An RC frame from a building is modeled with a 1-D interlocking TeSA shear wall.The effects of varying rigidity of the wall-frame connections(rigid,hinged,slotted)on the lateral strength of the system and the axial load demands of the gravity-load resisting systems are evaluated.Finally,the effect of connection details on the damage of the TeSA wall is also studied.The study shows that the lateral strength of the system is the highest with a rigid connection between the wall and the system,followed by the system with hinged connections.Slotted connections,which provided no vertical coupling between the wall and the frame result in the lowest lateral strength.TeSA wall experienced“slight damage”up to a drift ratio of 2%.The system with rigid connections between the wall and the frame experienced the most damage,followed by system with hinged and slotted connections.