1,721,088 research outputs found
Analysis of Reinforced Concrete Elements Including Shear Effects
Full text linkThis paper deals with the analysis of reinforced concrete (RC)plane frames under monotonic and cyclic loading, including axial,bending, and shear effects. A force-based two-dimensional (2D)element based on the Timoshenko beam theory is introduced. Theelement formulation is general and yields the exact solution withinthe Timoshenko beam theory. A simple, nonlinear, shear force-shear deformation law is used at the section level, together with aclassical fiber section for the axial and bending effects. Sheardeformations are thus uncoupled from axial and bending effects inthe section stiffness, but shear and bending forces become coupledat the element level because equilibrium is enforced along thebeam element. The element is validated through comparisons withexperimental data on the shear performance of bridge columns.The seismic analysis of a viaduct that collapsed during the 1995 Kobe earthquake is presented
Reinforced concrete fiber beam element with bond slip
No full textThis paper presents a new reinforced concrete beam finite element that explicitly accounts for the slip between the reinforcing bars and the surrounding concrete. The element formulation combines the fiber-section model with the finite-element model of a reinforcing bar with continuous slip. The section model retains the plane-section assumption, but the steel fiber strains are computed as the sum of two contributions, the rebar deformation and the anchorage slip. The model applies to any cross-sectional shape under biaxial bending and both monotonic and cyclic loads. The model theoretical framework is presented first. A sensitivity study on the monotonic and cyclic response of a reinforcing bar shows how the model traces the bar's reduced initial stiffness, bond degradation, and anchorage loss for insufficient anchorage length. Finally, comparison with an experimental test on a circular column shows that the prediction with the new model is in good agreement with the test, whereas the original fiber model with perfect bond overestimates the hysteretic energy dissipated during the loading cycles
Predictive model for the seismic vulnerability assessment of small historic centres: Application to the inner Abruzzi Region in Italy
No full textThe paper presents a predictive model for assessing the seismic vulnerability of small historic centres. The model, developed in the framing of other similar methods proposed in the past, needs a limited number of parameters and is based on information collected in the aftermath of the 2009 L'Aquila earthquake. First, a damage survey carried out on two historic centres hit by L'Aquila earthquake is presented and the most recurrent failure types are classified in terms of severity and extension, leading to damage probability matrices (DPMs). Second, the proposed predictive model is calibrated on the basis of simple observations on the buildings’ structural features. Finally, the model is validated through the application to a third historic centre characterized by the same features of the first two case studies. This application proves the generality of the proposed procedure by accurately reproducing the damage that was actually reported after the 2009 earthquake. The model provides useful information on the most effective anti-seismic strategies that could be implemented at the urban scale for seismic risk reduction
Analysis of R/C Beams Strengthened with FRP Plates
No full textThis paper discusses the problem of predicting the stiffness, the load capacity and the failure modes of RC members strengthened in bending with bonded steel or C-FRP thin plates. A critical issue of this strengthening technique is that when the plate debonds, the load capacity suddenly drops and the failure mode is typically brittle. Due to both the concrete cracking diffusion and the yielding of the steel rebars, a significant amplification of the bond stresses takes place at the beam-plate interface. Debonding occurs when the bond strength is reached locally. In order to properly describe and realistically predict the behavior of the strengthened beams, a displacement-based fiber beam model including bond slip is used. The proposed model is used to confirm and investigate distinct failure modes observed in experimental investigations
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