1,721,569 research outputs found
Flexural Strengthening of Real-Scale RC and PRC Beams with End-Anchored Pretensioned FRP Laminates
No full textAn experimental study on real-scale reinforced concrete (RC) and prestressed reinforced concrete (PRC) beams strengthened in flexure with fiber-reinforced polymer (FRP) laminates, developed at the University of Padova, Padova, Italy, is described in this paper. Externally bonded FRP reinforcement was applied in different ways with different types of end-anchorage devices and, in some beams, prestress transfer. After characterization of the single materials, four-point bending tests were executed and crack pattern and failure modes were studied, with particular attention to the behavior of the anchorages, consisting of two types of mechanical devices. Experimental results in terms of load- deflection response were then compared with the predictions of an analytical model, taking into account prestressing effects due to both internal strands and external FRP laminates, based on trilinear behavior characterized by section flexural crack initiation, steel yielding, and ultimate capacity
An experimentally based analytical model for the shear capacity of FRP-strengthened reinforced concrete beams
No full textThis paper deals with the shear strengthening of Reinforced Concrete (RC) flexural members with externally bonded Fiber-Reinforced Polymers (FRPs). The interaction between an external FRP and an internal trans- verse steel reinforcement is not considered in actual code recommendations, but it strongly influences the effi- ciency of the shear strengthening rehabilitation technique and, as a consequence, the computation of interacting contributions to the nominal shear strength of beams. This circumstance is also discussed on the basis of the results of an experimental investigation of rectangular RC beams strengthened in shear with “U-jacketed” carbon FRP sheets. Based on experimental results of the present and other investigations, a new analytical model for describing the shear capacity of RC beams strengthened according to the most common schemes (side-bonded and “U-jacketed”), taking into account the interaction between steel and FRP shear strength contributions, is proposed
Seismic assessment of complex historical buildings: application to Reggio Emilia cathedral, Italy
No full text
Analytical model for FRP confinement of concrete columns with and without internal steel reinforcement
No full textThe paper aims to contribute to a better understanding of the behavior of reinforced concrete columns confined with fiber- reinforced polymer FRP sheets. In particular, some new insights on interaction mechanisms between internal steel reinforcement and external FRP strengthening and their influence on efficiency of FRP confinement technique are given. In this context a procedure to generate the complete stress-strain response including new analytical proposals for 1 effective confinement pressure at failure; 2 peak stress; 3 ultimate stress; 4 ultimate axial strain; and 5 axial strain corresponding to peak stress for FRP confined elements with circular and rectangular cross sections, with and without internal steel reinforcement, is presented. Interaction mechanisms between internal steel reinforcement and external FRP strengthening, shown by some experimental results obtained at the University of Padova with accurate measurements, are taken into account in the analytical model. Four experimental databases regarding FRP confined concrete columns, with circular and rectangular cross section with and without steel reinforcement, are gathered for the assessment of some of the confinement models shown in literature and the new proposed model. The proposed model shows a good performance and analytical stress-strain curves approximate some available test results quite well
Fiber-reinforced polymer shear strengthening of reinforced concrete beams: Experimental study and analytical modeling
No full textIn this paper, the results of an experimental investigation on reinforced concrete (RC) rectangular beams strengthened in shear with externally bonded U-wrapped carbon fiber-reinforced polymer (CFRP) are presented and discussed. The results provide some new insights into the complex failure mechanisms that characterize the ultimate shear capacity of RC members with transverse steel reinforcement and FRP sheets and show some mechanisms of interaction between the externally applied FRP sheets and the internal shear steel reinforcement with different static schemes. This interaction is not considered in the actual code provisions but strongly influences the efficiency of the shear strengthening rehabilitation technique and, consequently, the calculation of the interacting contributions to the nominal shear strength of the structural member. On the basis of the observation of the experimental shear behavior, an analytical model, which allows the estimation of the interacting contributions to the shear capacity of the strengthened beams, is proposed
Ricerche sull’applicazione dei materiali compositi nel rinforzo di strutture in c.a. e c.a.p.
No full textFiber reinforced polymer shear strengthening of reinforced concrete beams with transverse steel reinforcement
No full textThe paper aims to contribute to a better understanding and modeling of the shear behavior of reinforced-concrete RC beams strengthened with carbon fiber reinforced polymer FRP sheets. The study is based on an experimental program carried out on 11 beams with and without transverse steel reinforcement, and with different amounts of FRP shear strengthening. The test results provide some new insights into the complex failure mechanisms that characterize the ultimate shear capacity of RC members with transverse steel reinforce- ment and FRP sheets. After the discussion of the above topics, a new upper bound of the shear strength is introduced. It should be capable of taking into account how the cracking pattern in the web failing under shear is modified by the presence of FRP sheets, and how such a modified cracking pattern actually modifies the anchorage conditions of the sheets and their effective contribution to the ultimate shear strength of the beams
- …
