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In this research, RBS effective parameters, on the seismic performance of beam-column connections have been investigated. In this study, finite element modelling analyses has been verified with a valid experimental specimen and the results are in good agreement. Ten models were numerically investigated. The investigated parameters are the various No. of IPB sections such as IPB120, IPB160, IPB200, and IPB240, changes in RBS beam cutting length (parameter b), changes in RBS beam cutting depth (parameter c), and changes in RBS beam cutting radius (parameter R). According to the numerical analysis, the moment-rotation curve, as well as the shape and stress distribution of the connection components, are examined for 10 different models. The results show that when the beam reaches the plastic moment area, the moment- rotation curve of the connection location is located in the elastic region. By decreasing the radius of the beam, the strength decreases and the energy dissipation decreases. Further, the results show that increasing parameter b (length of beam cutting), the strength and energy absorption capacity of the beam-column connection slightly decreases which is negligible. Therefore, with increasing parameter b, neither the RBS cutting depth, nor the RBS cutting radius has negative impact and it makes the initiative in executive and operational work to be higher and the executive restrictions to be less. The analysis of the distribution of von Mises stresses indicates the high ability of the beam to be connected with the reduced cross-section in the placement of the plastic joint tends in the reduced area of the beam flange in the area away from the connection.

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Under tension and compression, the wave crest and wave trough plastic zone of corrugated steel plate (CSP) have strong energy dissipation ability, but so far, the research on improving the energy dissipation capacity of building structure is very rare. To investigate behavior of the CSP, twelve models that consist of one to four folds with steel Q345B and Q235B, were simulated by using the finite element method. The numerical parameters varied in these models included geometries and materials of the corrugated steel plates. The results show that the CSP exhibits stable hysteretic behaviors, satisfactory energy dissipation capacities, large deformation and ductility capacity. Moreover, a method for estimating internal forces, yield displacement, yield load and stiffness of the CSP was derived and the derived equations provide reasonable predictions and shows agreement with theoretical values so can be used for future design. Based on the results, the parameter values of CSP that suitable for energy dissipation of building structures were suggested.

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In this paper, the free oscillations of a masonry panel made of unilateral No-Tension material are analysed, by adopting essentially the model proposed by Jacques Heyman. The aim of this analysis is to quantify the role of the elasticity in compression in the geometrically nonlinear dynamical response of Masonry-Like structures. Therefore, two unilateral models are considered: the first model assumes that the material is rigid in compression, the second one that the material is elastic in compression. Different levels of stiffness, in a range that covers realistic values of the Young modulus, are explored and the response of a simple panel subject to a fixed vertical compression and to different initial lateral disturbances are compared in order to estimate the effect of elasticity. As time histories for rigid and elastic panels display, the response of the rigid block is periodic and the response of the elastic block is quasi-periodic. In both cases the oscillation periods are visibly dependent on the amplitude. The periodicity of the elastic panels and its dependence on the amplitude is detectable also in the purely elastic phase, and is due to the physical nonlinearity induced by the unilateral material restrictions. The comparison between rigid and elastic time histories shows the main differences between the rigid and the elastic cases and allows to quantify the accuracy of the rocking-like assumption compared with the “harmonic type” simplification.

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Sudden failure of reinforced concrete or prestressed concrete bridges and viaducts occurred in Italy in the last few years due to brittle failure of Gerber supports subjected to degradation of material such as corrosion of steel bars. The danger of sudden and brittle failure is often due to pitting corrosion, loss of bond in steel bars and concrete crushing. In this paper, the risk of failure of Gerber supports in service condition and at ultimate state under vertical and lateral loads was investigated focusing on the consequences of pitting corrosion and loss of bond in steel bars. A simplified strut-and-tie model was developed to predict flexural response of Gerber supports including effects of corrosion of steel bars, loss of bond and concrete crushing due to the biaxial state of stresses. Several experimental studies regarding the flexural behavior of RC beams with Gerber supports were collected to validate the proposed model. The topic of this research is of particular interest for existing bridges with Gerber supports to be retrofitted or strengthened for seismic verification.

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The main motivation of current study is to present the results of an investigation conducted to obtain a relationship between damage index/damage level and residual displacement. SDOF systems with known lateral strength for periods ranging from 0.1 to 3.0 seconds are investigated for this purpose. Two hysteretic behaviours consisting of elastoplastic (non-degrading) and Modified Clough (degrading) models are assumed during analyses. A total of 140 ground motions including both far-field and near-field ground motions are considered in nonlinear dynamic time history analyses. A new damage index is proposed in terms of residual displacement, spectral displacement, maximum inelastic displacement and lateral strength. The comparison of proposed damage index with the analysis results is also presented.

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The study evaluates the seismic reliability of isolated multi-span continuous deck bridges considering the influence of the friction pendulum isolators and provides seismic reliability-based design abacuses as a function of both the structural properties and reliability level expected. The behavior of these systems is analyzed by employing five degrees of freedom accounting for five vibrational modes of the elastic reinforced concrete pier and a single degree of freedom to model the response of the infinitely rigid deck equipped with the isolators. The reinforced concrete abutment is modelled as a fixed support. The non-linear FPS response is described also considering the velocity-dependent behavior. The uncertainty in the seismic input is taken into account through a set of natural records with different characteristics scaled to increasing intensity levels. The uncertainty on the friction coefficient is modelled through an appropriate probability density function. Within an extensive parametric study developed for different isolator and system properties, fragility curves of both the pier and isolation system supporting the deck are evaluated. In line with the hazard curve of the reference site, the corresponding seismic reliability curves are computed by means of the convolution integral. Finally, seismic reliability-based design abacuses for different structural properties are proposed.

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In this research, cold formed steel sections have been used to reinforce and rectify the axial and shear performance of unstiffened, stiffened, L-shaped and T-shaped CFT columns. At first stage, Five L-shaped and Five T-shaped CFT columns, stiffened by various longitudinal internal steel plates and steel pipes subjected to axial and lateral loading, were numerically investigated. The variable study included the shape of CFT columns, various stiffening steel section, and the interaction between stiffening steel and concrete. Primarily FEM procedure had been verified with some available experimental results. The results indicate that the stiffening steel section have a great influence in the performance of L- and T- shaped CFT columns. Also, T-shaped CFT column shows the higher performance in terms of strength, stiffness and ductility than L-shaped section.
At second stage, the base model was CFT column as a benchmark specimen and three new and innovative type of CFT columns with difference in their longitudinal stiffening steel were investigated under axial and cyclic loading. The results show that reinforcement of CFT columns by this method, lead to enhancement in load carrying capacity, enhancement in lateral drift ratio, ductility, preventing of local buckling in steel wall, and enhancement in energy dissipation.

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Special and intermediate moment resisting frames are two main types of lateral load resisting systems used in high-seismic regions, depending on the height of the building. Current design codes consider only earthquake risks in the design of these structures and neglect subsequent hazards. The current study compares the multi-hazard robustness of these alternative designs for earthquake and subsequent fire. For this purpose, two special and intermediate four-bay four-story steel moment frames were designed and subjected to different earthquake intensities and fire scenarios. Three types of failures, including local failure (failure of beams), partial failure (failure in some elements but not the entire structure), and global failure (overall instability of the structure), were encountered in the analyzed models. It was observed that the intermediate frame had higher fire resistance against one-bay fire scenarios than the special frame. On the contrary, when the fire was considered in an entire story, the fire resistance of both models decreased considerably with increasing earthquake intensity.

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