Seismic Rehabilitation of RC Structural Walls

Structural walls in existing buildings designed to pre 1970s codes may have deficient shear reinforcement and lap splice detailing. Lap splices at the bottom of the walls were designed in compression with anchorage length of 24-bar diameter. When the structural wall is subjected to lateral loads during a major seismic event, the lap splice is in the zone of maximum moment and shear and may be subjected to tension. Such design may cause nonductile behaviour and sudden failure of the wall due to shear or bond slip of the lap splice reinforcing bars. The effect of shear and ductility rehabilitation on the behaviour of reinforced concrete structural walls, without lap splice, have shown improvement in the structural wall shear resistance and ductility and hence overall structural ductility and seismic loads resistance. Research on rehabilitation of reinforced concrete (RC) structural walls with both deficient shear reinforcement and lap splice detailing is still needed. The principal objectives of this study were to evaluate the seismic behaviour of non-ductile reinforced concrete structural walls before and after rehabilitation using carbon fibre reinforced polymers (CFRP). These objectives were achieved through experimental and analytical investigations. The experimental phase of this research involved testing large scale models of RC structural walls with deficient shear strength and lap splice detailing to reproduce failure modes observed following major seismic events and to evaluate the rehabilitation schemes. Ten RC structural walls were built and tested under cyclic loading. Three control walls were tested as-built with non-ductile detailing and seven walls were rehabilitated before testing. The purpose of the rehabilitation techniques was to prevent brittle failure in shear or bond slip and to improve the ductility and energy dissipation of RC structural walls. The analytical phase of this study involved evaluation of the inelastic dynamic response of RC residential building with nonductile structural walls as well as retrofitted walls. An

[1]  Denis Mitchell,et al.  SEISMIC RETROFIT OF SHEAR WALLS WITH HEADED BARS AND CARBON FIBER WRAP , 2003 .

[2]  Parviz Soroushian,et al.  Pullout Behavior of Hooked Bars in Exterior Beam-Column Connections , 1988 .

[3]  Amr S. Elnashai,et al.  Experimental behaviour of reinforced concrete walls under earthquake loading , 1990 .

[4]  Michael D. Kotsovos,et al.  STRENGTH AND DEFORMATION CHARACTERISTICS OF REINFORCED CONCRETE WALLS UNDER LOAD REVERSALS , 1990 .

[5]  F. Vecchio,et al.  THE MODIFIED COMPRESSION FIELD THEORY FOR REINFORCED CONCRETE ELEMENTS SUBJECTED TO SHEAR , 1986 .

[6]  Parviz Soroushian,et al.  Bond of Deformed Bars to Concrete: Effects of Confinement and Strength of Concrete , 1991 .

[7]  J. Conte,et al.  Flexural Modeling of Reinforced Concrete Walls- Model Attributes , 2004 .

[8]  A. Kappos,et al.  CYCLIC TESTS ON SEISMICALLY DAMAGED REINFORCED CONCRETE WALLS STRENGTHENED USING FIBER-REINFORCED POLYMER REINFORCEMENT , 2003 .

[9]  Sharon L. Wood,et al.  Performance of Reinforced Concrete Buildings during the 1985 Chile Earthquake: Implications for the Design of Structural Walls , 1991 .

[10]  J. Mander,et al.  Theoretical stress strain model for confined concrete , 1988 .

[11]  Alfredo H.-S. Ang,et al.  Damage Estimation of Existing Bridge Structures , 1993 .

[12]  James Michael LaFave,et al.  A PRACTICAL MODEL FOR SEISMIC ANALYSIS OF REINFORCED CONCRETE SHEAR WALL BUILDINGS , 2005 .

[13]  Michel Bruneau,et al.  Analysis and Design of Low-Rise Masonry and Concrete Walls Retrofitted Using Steel Strips , 2000 .

[14]  José I. Restrepo,et al.  INVESTIGATION OF CONCENTRICALLY LOADED REINFORCED CONCRETE COLUMNS CONFINED WITH GLASS FIBER-REINFORCED POLYMER JACKETS , 2001 .

[15]  Michael P. Collins,et al.  A general shear design method , 1996 .

[16]  D. Mitchell,et al.  Prestressed Concrete Basics , 1994 .

[17]  T. Paulay,et al.  Stability of Ductile Structural Walls , 1993 .

[18]  Mo Shing Cheung,et al.  Seismic Strengthening and Repair of Reinforced Concrete Shear Walls , 2000 .

[19]  Amir Mirmiran,et al.  Model of Concrete Confined by Fiber Composites , 1998 .

[20]  Mário Lopes.  Experimental shear-dominated response of RC walls: Part I: Objectives, methodology and results , 2001 .

[21]  Sami H. Rizkalla,et al.  Confinement Model for Axially Loaded Concrete Confined by Circular Fiber-Reinforced Polymer Tubes , 2001 .

[22]  Y. K. Wen,et al.  Damage-Limiting Aseismic Design of Buildings , 1987 .

[23]  Parviz Soroushian,et al.  LOCAL BOND OF DEFORMED BARS WITH DIFFERENT DIAMETERS IN CONFINED CONCRETE , 1989 .

[24]  Ezio Giuriani,et al.  Cyclic behaviour of a full scale RC structural wall , 2003 .

[25]  Martin S. Williams,et al.  Laboratory testing of structures under dynamic loads: an introductory review , 2001, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[26]  A. Ghobarah,et al.  BEHAVIOUR OF REHABILITATED STRUCTURAL WALLS , 2005 .