Failure diagrams of FRP strengthened RC beams

Amongst various methods developed for strengthening and rehabilitation of reinforced concrete (RC) beams, external bonding of fibre reinforced plastic (FRP) strips to the beam has been widely accepted as an effective and convenient method. The experimental research on FRP strengthened RC beams has shown five most common modes, including (i) rupture of FRP strips; (ii) compression failure after yielding of steel; (iii) compression failure before yielding of steel; (iv) delamination of FRP strips due to crack; and (v) concrete cover separation. In this paper, a failure diagram is established to show the relationship and the transfer tendency among different failure modes for RC beams strengthened with FRP strips, and how failure modes change with FRP thickness and the distance from the end of FRP strips to the support. The idea behind the failure diagram is that the failure mode associated with the lowest strain in FRP or concrete by comparison is mostly likely to occur. The predictions based on the present failure diagram are compared to 33 experimental data from the literature and good agreement on failure mode and ultimate load has been obtained. Some discussion and recommendation for practical design are given.

[1]  Y. Mitsui,et al.  A study on shear reinforcement of reinforced concrete beams externally bonded with carbon fiber sheets , 1997 .

[2]  P. Hamelin,et al.  Strengthening of concrete beams using fiber-reinforced platics , 1997 .

[3]  PREDICTION OF PEELING BEHAVIOUR OF REINFORCED CONCRETE BEAMS WITH EXTERNALLY BONDED PLATES. DISCUSSION. , 1997 .

[4]  M Raoof,et al.  PEELING FAILURE OF REINFORCED CONCRETE BEAMS WITH EXTERNALLY BONDED STEEL PLATES , 1995 .

[5]  Hee Kiat Cheong,et al.  Brittle Failure and Bond Development Length of CFRP-Concrete Beams , 2001 .

[6]  A. Hutchinson,et al.  CONCRETE BEAMS STRENGTHENED WITH EXTERNALLY BONDED FRP PLATES , 2001 .

[7]  J. Teng,et al.  INTERFACIAL STRESSES IN BEAMS AND SLABS BONDED WITH THIN PLATE , 2001 .

[8]  H. Saadatmanesh,et al.  Design Guidelines for Flexural Strengthening of RC Beams with FRP Plates , 1998 .

[9]  O. Chaallal,et al.  SHEAR STRENGTHENING OF RC BEAMS BY EXTERNALLY BONDED SIDE CFRP STRIPS , 1998 .

[10]  H. Saadatmanesh,et al.  Shear and Flexural Strengthening of R/C Beams with Carbon Fiber Sheets , 1997 .

[11]  Thanasis Triantafillou,et al.  Strengthening of RC beams with epoxy-bonded fibre-composite materials , 1992 .

[12]  Hamid Saadatmanesh,et al.  Prediction Of Failure Load Of R/C Beams Strengthened With FRP Plate Due To Stress Concentration At T , 1998 .

[13]  H. Saadatmanesh,et al.  RC Beams Strengthened with FRP Plates. II: Analysis and Parametric Study , 1991 .

[14]  Carlo Pellegrino,et al.  Fiber-Reinforced Polymer Shear Strengthening of Reinforced Concrete Beams with Transverse Steel Reinforcement , 2002 .

[15]  A. Nanni,et al.  BRITTLE FAILURE IN FRP PLATE AND SHEET BONDED BEAMS , 1997 .

[16]  Ching Chiaw Choo,et al.  Flexural Behavior of R/C Beams Strengthened with Carbon Fiber Reinforced Polymer Sheets or Fabric , 2003 .

[17]  J. W. Tedesco,et al.  Strengthening of Reinforced Concrete Beams with Externally Bonded Composite Laminates , 1999 .

[18]  Joseph W. Tedesco,et al.  Analysis of Reinforced Concrete Beams Strengthened with FRP Laminates , 2000 .

[19]  Mohamed Maalej,et al.  Interfacial shear stress concentration in FRP-strengthened beams , 2001 .

[20]  Jang-Kyo Kim,et al.  Experimental study on RC beams with FRP strips bonded with rubber modified resins , 2004 .

[21]  J. W. Tedesco,et al.  PREDICTION OF ANCHORAGE FAILURE FOR REINFORCED CONCRETE BEAMS STRENGTHENED WITH FIBER-REINFORCED POLYMER PLATES , 2001 .

[22]  Scott T. Smith,et al.  FRP: Strengthened RC Structures , 2001 .

[23]  D. Gemert,et al.  Effect of Longitudinal Carbon Fiber Reinforced Plastic Laminates on Shear Capacity of Reinforced Concrete Beams , 1999, SP-188: 4th Intl Symposium - Fiber Reinforced Polymer Reinforcement for Reinforced Concrete Structures.

[24]  Deric J. Oehlers,et al.  Premature Failure of Externally Plated Reinforced Concrete Beams , 1990 .

[25]  Mohammed H. Baluch,et al.  Guidelines Toward the Design of Reinforced Concrete (RC) Beams with External Plates , 1994 .

[26]  T. M. Roberts,et al.  DISCUSSION. THEORETICAL STUDY OF THE BEHAVIOUR OF REINFORCED CONCRETE BEAMS STRENGTHENED BY EXTERNALLY BONDED STEEL PLATES. , 1989 .

[27]  Y. Frostig,et al.  Closed-Form High-Order Analysis of RC Beams Strengthened with FRP Strips , 2000 .

[28]  Sami H. Rizkalla,et al.  Fiber Reinforced Polymer Reinforcement for Concrete Structures , 1999, SP-188: 4th Intl Symposium - Fiber Reinforced Polymer Reinforcement for Reinforced Concrete Structures.

[29]  T. Triantafillou.  Shear Strengthening of Reinforced Concrete Beams Using Epoxy-Bonded FRP Composites , 1998 .

[30]  D. Hui,et al.  Mechanics of bonds in an FRP bonded concrete beam , 2001 .

[31]  Costas P. Antonopoulos,et al.  Design of Concrete Flexural Members Strengthened in Shear with FRP , 2000 .

[32]  M Raoof,et al.  AN INSIGHT INTO THE STRUCTURAL BEHAVIOUR OF REINFORCED CONCRETE BEAMS WITH EXTERNALLY BONDED PLATES. , 1997 .

[33]  Tarek H. Almusallam,et al.  Ultimate strength prediction for RC beams externally strengthened by composite materials , 2001 .

[34]  U. Neubauer,et al.  DESIGN ASPECTS OF CONCRETE STRUCTURES STRENGTHENED WITH EXTERNALLY BONDED CFRP-PLATES , 1997 .

[35]  Oliver Kelly,et al.  Ultimate Response of RC Beams Strengthened with CFRP Plates , 2001 .

[36]  C. Leung.  Delamination Failure in Concrete Beams Retrofitted with a Bonded Plate , 2001 .

[37]  Marie-José Nollet,et al.  Strengthening of reinforced concrete beams with externally bonded fiber-reinforced-plastic plates: design guidelines for shear and flexure , 1998 .

[38]  Bo Gao,et al.  Prediction of concrete cover separation failure for RC beams strengthened with CFRP strips , 2005 .

[39]  O. Buyukozturk,et al.  FAILURE BEHAVIOR OF PRECRACKED CONCRETE BEAMS RETROFITTED WITH FRP , 1998 .