Mauro Torquati

Horizontal cladding panels: in-plane seismic performance in precast concrete buildings

The paper investigates the in-plane performance of horizontal precast reinforced concrete cladding panels, typically adopted in one-storey precast industrial and commercial buildings. Starting from in-field observations of cladding panels failures in recent earthquakes, the seismic performance of typical connections is evaluated by means of experimental tests on full-scale panels under quasi-static cyclic loading. The failure mechanisms highlight the vulnerability of such connections to relative displacements and, therefore, the need to accurately evaluate the connections displacement demand and capacity. An analytical model is developed to describe the force–displacement relationship of the considered connections and compared to the experimental results. In order to determine the seismic vulnerability of such connections and provide design recommendations, linear and nonlinear analyses are conducted taking as reference a precast concrete structure resembling an industrial precast building. The results of the analyses show the importance of a correct estimation of the column’s lateral stiffness in the design process and how an improper erection procedure leads to a premature failure of such connections.

A Novel Framework to Include P-Δ Effects in Displacement-Based Seismic Assessment

During an earthquake, P- effects could significantly increase the horizontal displacements in a structure; hence, they should be duly accounted for in seismic assessment procedures. Considering the displacement based assessment (DBA) procedure, P- effects influence the single degree of freedom substitute structure adopted in the procedure both in terms of shear-displacement relationship and of equivalent viscous damping. The present article considers a novel framework to include P- effects in the DBA procedure. The application of the proposed procedure is illustrated considering the Takeda hysteresis model commonly adopted for reinforced concrete structures.

Displacement-Based Seismic Assessment for Precast Concrete Frames with Non-Emulative Connections

ABSTRACT The paper develops a methodology for the seismic vulnerability assessment, Displacement-Based Assessment (DBA), of one-story and multi-story precast concrete frames with non-emulative connections. The method is based on the Direct Displacement-Based Design procedure initially developed by Priestley. The DBA is particularly suitable for the evaluation of the seismic response of flexible structures, as it considers displacements as the leading parameters to estimate the seismic vulnerability. The proposed procedure specifically accounts for the influence of beam–column connections, P-∆ effects, and second mode of vibration. The validation has been performed by means of nonlinear time history analyses.