Behaviour of Structural Elements Constructed and Rehabilitated With High Performance Concretes

Abstract

<p>An extensive experimental investigation coupled with Code based/design-oriented analysis was conducted on the performance and application of high-performance concretes (HPCs) including self-consolidating concrete (SCC), engineered cementitious composite (ECC) and ultra-highperformance concrete (UHPC) in different reinforced structural elements. Ten 1/3 scale exterior shear deficient beam-column connections were tested under torsional and bending loading. Ten rd 1/3 scale building frames (three shear and seven flexure critical) and seven framed shear walls were tested under reversed cyclic lateral loading. Twenty-three 1/5 scale ECC/UHPC/SCC jacketed strengthened/repaired reinforced SCC piers/columns were tested under axial loading to failure. The incorporation of ECC and UHPC in full frame or joint region (in plastic hinge zone) as replacement of SCC in shear deficient specimens changed brittle shear failure to desired ductile flexural failure mode while significantly increasing bending/torsional/cyclic or hysteretic load and deformability/ductility capacities. ECC/UHPC made specimens exhibited higher energy absorption and damage tolerance capacities with better crack control characteristics as well as potentially lower longitudinal and hoop/shear reinforcement requirements which can significantly improve seismic behaviour. The strain hardening with multiple cracking and limiting crack width characteristics of ECC lowered the initial stiffness and stiffness degradation with the ability to maintain good damping behaviour during lateral cyclic loading of building frames and framed shear wall system. The tested ECC framed shear wall specimens under lateral cyclic loading had higher ultimate load and deformability capacities compared to their SCC counterparts. This was attributed to better transfer of shear stress through cracks due to fiber bridging and multiple cracking with small crack width in ECC compared to SCC/UHPC. Piers rehabilitated and strengthened with ECC/UHPC jackets showed higher strength. However, ECC specimens showed better performance in terms of enhanced confining effect along the height exhibiting ductile failure compared to their SCC/UHPC counterparts which showed brittle crushing failure at the top with jacket spalling. Existing Codes and other analytical equations need to be modified for the design of ECC/UHPC incorporated structural components. This study revealed great potential of ECC/UHPC repair/strengthening technology and ECC/UHPC incorporated building frames, beam-column connections and framed-shear wall system having higher torsional, flexural and shear resistance in practical construction.</p>