1,721,048 research outputs found
Reinforced concrete structural elements cast into wood-chip cement formworks subjected to compression and out-of-plane bending
No full textThe mechanical response of reinforced concrete walls cast into permanent woodchip-cement formworks and subjected to eccentric compression has been assessed with experimental tests of full-scale panels and an analytical approach has been proposed. The load-bearing capacity of the wall panel is assured by the inner reinforced concrete grid structure, composed of vertical columns and horizontal ribs, reinforced with vertical and horizontal steel bars. The experimental specimens were realized varying the concrete cross-section and tested varying the eccentricity of the applied vertical load. Both reinforced and non-reinforced panels were tested. An analytical model is proposed to evaluate the load-bearing capacity, based on dimensionless curves, which provide reduction coefficients of strength based on eccentricity and slenderness, considering second-order effects. The analytical model demonstrates a reliable prediction of the experimental peak loads
Seismic Behavior of Precast Buildings With Dissipative Connections
Full text linkRecent earthquakes in southern Europe highlighted that the connections of cladding panels to R.C. frames in precast buildings had a major role in the structural collapse. For this reason, there is an urgent need for a review of the design methods for these connections as well as for an improvement in the manufacturing technology. This article aimed to assess the efficiency of dissipative panel-to-structure and roof connections in R.C. precast buildings. A parametric study consisting of linear and non-linear analyses on one case-study building is performed. Different sensitivity analyses are performed varying their mechanical properties (i.e., stiffness, strength, and ductility) to analyze the behavior of the CP/frame connections. The study focuses on dissipative connections with an elastic–plastic behavior, placed between cladding panels (CPs) and frames in precast buildings with stacked horizontal cladding panels. The introduction of dissipative CP/frame connections implies the inclusion of panels in the global seismic resisting system. The “panels + frame” system highlights a high stiffness until the yield strength of the CP/frame connections is reached. The results, obtained from non-linear dynamic analyses (NLDAs), clearly show how the proposed connection improves the structural seismic performance. By contrast, this is no longer true for R.C. precast structures with flexible diaphragms, especially for intermediate columns, far from panels aligned to seismic action. In this case, significant and unexpected axial forces arise on out-of-plane connections between panels and columns. The integration of an efficient diaphragm is essential to prevent these critical issues both on intermediate columns and CP/column connections; it enables the dissipative capacity of the “panels + frame” system, and it significantly limits the forces and displacements of intermediate alignments. Unfortunately, the achievement of a rigid diaphragm is not always feasible in precast buildings. A possible alternative to activate dissipative capacities of the roof diaphragm with limited in-plane stiffness is the use of dissipative connections linking roof beams and main beams. The solutions described in this article can be applied both in the design of new buildings and for the seismic upgrading of existing ones with easy-to-install and low-impact applications
La modellazione numerica delle strutture della basilica e le verifiche di stabilità e di vulnerabilità sismica
No full textRole of fastenings in modifying the hysteretic response of panel-to-panel joints for CLT structures
No full textHigh performance dampers are a key component in low-damage earthquake-resistant timber structures and they should be designed according to displacement-based design criteria. In this case, a well-defined non-linear force vs displacement relationship of the connection is to be known by the designer (e.g., to evaluate inter-storey drifts), underlying the importance of their careful experimental characterization. In this study, the cyclic shear response of a panel-to-panel joint, fastened to the wooden elements with three alternative solutions, was experimentally tested. Results showed that, although fulfilling the capacity design criteria and allowing an easy replacement of the damper, the semi-rigid nature of fastenings produces important modifications to the mechanical properties of the whole connection type, such as elastic stiffness, yielding point, ductility and equivalent viscous damping
Modello diffusivo e di danno per l'analisi del degrado di strutture di calcestruzzo armato
No full text
- …
