properties of masonry were: 8.5 MPa for the compressive strength, 8500 MPa and 3400 GPa for the elastic and the shear moduli, respectively, and a Coulomb law for shear strength calibrated with parameters equal to 0.3 as cohesion and 0.4 as friction coefficient. High-strength CFRP applied in strips 100 mm wide were considerd, having nominal elastic modulus of 230 GPa and equivalent thickness of 0.165 mm. Loads derived from a three storey building were assumed, and the simulation of the effect on the base floor was performed.

From Table 2, the maximum fracture energy and the limit of experimental delamination are thus about 25 and 5 times higher than the valued proposed by the code, respectively. Four configurations were considered, characterized by progressive reinforcement, from plain masonry to global horizontal confinement, up to application of horizontal and vertical strips on the main walls, 50 cm spaced (Figure 12). Non-linear push-out analysis were performed, by considering progressive increase of horizontal acceleration, uniformly distributed along the height of the wall.

The numerical results are given in Figures 13 to 15. To take into account a possible residual bond after delamination occurrence, the comparison between the assumption of a elastic-brittle or elastic-plastic law for the FRP behaviour was considered.

Despite the simplification adopted in the modelling, several points can be discussed, by analyzing the diagrams which compare the imposed acceleration to the displacement at the control point (Figure 12.a). First (Figure 13), by considering the experimental elaboration on fracture energy and delamination, the unreinforced model is subjected mainly to rocking, confirming the high vulnerability of masonry buildings to rigid movements (a). The shear strength is not activated in the walls, and the preliminary horizontal tying is not able to increase the peak load, but only to homogenize the plateau in the plastic branch (b). By introducing vertical strips, the load is significantly increased, with minor differences between flexural (c) and combined shear (d) reinforcement. The elasto-plastic behaviour of FRP is able to increase of about 25% the peak load in the complete strengthening configuration, and to guarantee a constant plastic plateau (Figure 14).

Evoe rime his!. FRP el fttle

Evoe rime his!. FRP el fttle

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