Advanced Techniques for Pilotis RC Frames Seismic Retrofit: Performance Comparison for a Strategic Building Case Study

Abstract

Pilotis buildings have widely spread out in developed countries since World War II onwards. From the structural point of view, Pilotis RC frames exhibit substantial lack in ductility capacity and shear resistance localized at the first floor, since they have been mainly realized before the seismic codes’ era. The present study shows the performance comparison of four advanced retrofit techniques when applied to typical Pilotis RC frame designed for gravity loads only according to Italian building code of ‘60s. A preliminary investigation has been performed to select non-linear numerical models suitable to describe the considered RC frame behavior, involving flexural inelastic hinges of RC beams and columns and in-plane axial inelastic hinges of masonry infill panels. Two seismic retrofit projects have been designed at a local level, by strengthening the masonry infilled panels with Fiber Reinforced Cementitious Matrix (FRCM) technique and alternatively by replacing infilled panels with prefabricated panels disconnected from the structure, so that no infill/frame interaction occurs. Two more retrofit projects have been designed at a global level, in order to improve the overall structural performance making use of energy dissipation and, alternatively, base isolation techniques. Nonlinear time history analysis and structural assessment have been carried out for the as-built case as well as for the four retrofit solutions according to Eurocode 8 and Italian Building Code, in order to highlight the structural deficiencies and relative improvements, respectively. Performances offered by the proposed retrofit techniques have been finally compared in terms of structural behavior, expected damage, and economic impact.

Multiscale Numerical Analysis of TRM-Reinforced Masonry under Diagonal Compression Tests

“…f , = 2A (2) where Fmax,i is the maximum shear load and Ai the specimen's transversal area parallel to the mortar joint. The average bond strengths for the three tested brick-mortar interfaces are listed in Table 6.…”

“…A suitable procedure to select buildings needing structural rehabilitation is out of the scope of the present paper. The authors believe that the proposed numerical approach will be a useful tool for retrofit intervention design [1,2]. Jacketing historical masonry structures with steel-reinforced concrete is among the most conventional techniques for seismic retrofitting.…”