Seismic Performance of High-Strength Self-Compacting Concrete in Reinforced Concrete Beam-Column Joints

摘要

Because of its potentially beneficial properties, there has been an increased interest in recent years on performance of self-compacting concrete (SCC) in structural members. The capability of SCC in flowing through and filling in even the most congested areas makes it ideal for use in congested reinforced concrete (RC) structural members such as beam-column joints (BCJ). However, members of tall multistory structures impose high capacity requirements where implementing normal-strength self-compacting concrete (NSSCC) is not preferable. In the present study, six beam-column joint specimens were designed following the guidelines of the New Zealand concrete standards; namely, three high-strength self-compacting concrete (HSSCC), one conventionally vibrated high-strength concrete (CVHSC), one conventionally vibrated concrete (CVC), and one CVC with HSSCC in its joint region. Factors such as the concrete type (HSSCC, CVHSC, and CVC), amount of joint shear stirrups, axial load ratio (1% and 10% of section capacity), and direction of casting were considered as variables in designing these specimens. All BCJs were tested under a displacement-controlled quasi-static reversed cyclic loading regime. Seismically important features such as shear force, drift ratio, member deformations, strains, crack pattern, and crack width were measured; and damping, stiffness, joint shear stress, contribution of different components, and elongation of plastic hinge zone were calculated. Joint shear stresses were varied from 6 to 7 MPa; yet within the maximum code limit of about 10 MPa. It was found that not only none of the seismically important features were compromised by using HSSCC, but also the quality of material and ease of construction boosted the performance of beam-column subassemblies.