1,721,127 research outputs found
Detection of damage due to corrosion in prestressed RC beams by static and dynamic tests
No full textAbstract
In this paper, the behaviour of pre-stressed RC beams with compressive concrete subjected to damage due to reinforcement corrosion has been experimentally investigated. The experimental static and dynamic analysis is described. The results of static bending tests show that the corrosion leads to an increase of curvature for prestressed RC section, a decrease of stiffness and, as evident, a non linear behaviour of damaged beam under low service loads. Dynamic tests allow to record variations of frequency response both for undamaged and damaged beams at different modes of vibration. Finally, a damage coefficient has been evaluated for damaged beams
Experimental analysis of bond-slip effects in RC beams strengthened with NSM CFRP rods
No full textThe use of the near surface mounted (NSM) fiber reinforced polymer (FRP) technique for retrofitting RC beams is a mainstream. Nevertheless, the bond mechanisms of FRP rods between rods and adhesive resin and/or rod–resin with concrete surfaces are not known completely. This paper investigates the experimental bond-slip effects of circular and rectangular carbon-FRP (CFRP) rods inserted in grooves in RC elements through experimental pull-out and bending tests, and using theoretical models. Five RC beams were built and subjected to bending loading; three of the ones strengthened using NSM CFRP rods were subjected to bending until failure. The experimental results showed changes in the response of beams such as stiffness in the elastic phase, reduction of ultimate capacity and ductility due to bond-slip effects. On the other hand, strain measurements on CFRP rods recorded by pull-out tests theoretically valid the linear elastic analysis capable of defining the behavior of CFRP rods before loss of bond. Finally, the comparison between experimental results and theoretical data opens a discussion concerning bond-slip effects in cracked RC beams strengthened with NSM CFRP rods and leads to the definition of actual strain limits for FRP under service loads
Effects of the concrete damage due to corrosion of steel bars on the static and dynamic response of PRC/RC beams
No full text
A reflection on the application of vibration tests for the assessment of cracking in PRC/RC beams
No full textOccurrence of cracking damage in a structural, reinforced, concrete element leads to changes in its dynamic response. Nevertheless, the typical non-linear behavior of prestressed reinforced concrete (PRC) and reinforced concrete (RC) beams is characterized by cracking, due to the low tensile strength of concrete. It is necessary to take adequate account of cracking effects, in vibration-based monitoring of PRC/RC beams’ structural health, by distinguishing cracking of tensile concrete due to bending moment under service loads; which does not reduce the structural availability of beams although it modifies their dynamic response, from real damage deriving from defects, loss of integrity and cracking due to overloading during service life. This paper deals with cracking effects through an investigation of PRC/RC beam models in real scale, subjected to increasing static loading and natural vibration tests. Degradation of stiffness and development of cracking were related to frequency values measured in a frequency range through vibration tests on free end beams. The results are compared with theoretical values and discussed
- …
