3.3.1. Comparison of the strengthening techniques

Below is presented the building performance degree with TRM reinforcement. The same graph shows the performances of both KTP and Eurocode spectra.

Figure 3-44 Performance point – Steel Frames

With the reinforcement the performance point is achieved for higher displacements and higher spectral accelerations, that in the case without reinforcement. So, in general the building more ductile and is safer. Also, according to EC8, the building withstands without collapse the design earthquake. It doesn’t cause any damages, since it reaches the performance point, before reaching the displacement that cause a limit state of LS2. We can see that with EC8, with the steel frames, the performance point is reached in the linear state. Also, the it allows very high displacements since the service limit state of displacement LS3 and LS4, are not in the graph.

3.3.1. Comparison of the strengthening techniques The reinforcements studied above give different effects on the reference building under consideration. The parameters that affect the results are the modulus of elasticity of reinforcement and its equivalent thickness. Impacts of the modulus of elasticity and equivalent thicknesses are greater when these two values increase. Below are presented the comparison of nonlinear analysis curves for the four reinforcements:

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Figure 3-45 Comparison of the capacity curve X direction

From these curves it is observed that steel frames increase the capacity shear strength, but does not greatly increase ductility. On the other hand, CFRP and TRM reinforcements are very close to each other. CFRP also has quite good ductility although they have the same bearing capacity with TRM. However, to create an idea clearer what happens to the building is necessary to compare interstory drifts for all cases. From the relative displacements it is observed that for carbon fiber reinforcement CFRP and TRM does not we have good distribution of relative displacements. We have the creation of the weak floor in the second floor while on the other floors the masonry undergoes small displacements (the ferrocement case in in the third floor). This type of reinforcement is not suitable for the result if all carbon fiber floors were to be coated, but this would lead to cost increase by over 80%. Only the steel frames control the displacement and, in that case, we have a good distribution of the shear forces. In addition to the bearing capacity of the structure, it is important to compare them in the term of performance degree. Seismic performance expresses the effect of a seismic spectrum on the building under study. Below are presented in tabular form the performance of the building for each case.

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