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Several researchers propose placing diagonal reinforcing bars at the base of the wall to treat the shear slip, while others have suggested various ways to address this problem associated with halting the effects incurred by the through-crack in the base of the wall during cyclic loading. An indicative proposal of the bibliography is the use of large diameter reinforcement bars in the web of the wall as vertical reinforcements, so as to be able to better control the shear action through the dowel action of these bars. The two aforementioned proposals, while adequately addressing the phenomenon of shear slip, present significant disadvantages. The use of diagonal reinforcement is very difficult to construct, because of the density of the existing reinforcement in the base of the walls, which involves compromising good concrete condensation. Also, the use of large diameter vertical reinforcement along the length of the whole wall section, including its web, is a strongly uneconomical solution. This work examines a solution without the aforementioned side-effects. The innovation of the present work is the fact that it positions stoppers in combination with the use of conventional reinforcing bars at positions in the critical zones of the walls, in order to prevent the expected slip along the through-crack in the base of the rigidly supported wall. The work is experimental and includes two stages. The first stage was carried out with the construction of six test specimens, which can be considered as preliminary base specimens used for a first examination of the mechanical behavior of the walls with integrated steel hollow beams at their ends. These test results are a prelude to the second stage of the present study, including the experimental investigation of the seismic mechanical properties of a wall specimen, detailed either with conventional reinforcement according to EC8 or with the same conventional reinforcement but including also steel hollow beams at its confined edges.

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The paper is focused on the seismic performance of steel storage pallet racks, which represent a very competitive solution, widely used to store goods and materials. In particular, the design strategy herein proposed is based on a procedure which directly correlate the static and the seismic rack performance using the so-called Incremental Dynamic Analysis (IDA) approach. Despite this approach is a well-established analysis method, generally used for defining the risk associated with seismic events, it is rarely employed in the routine design of steel racks. In fact, independently of the complexity of the racks under investigation, only the modal response spectrum analysis (MRSA) is usually adopted, neglecting hence some non-negligible peculiarities of these structures. This is mainly due to the lack of time during the design phases.
The proposed procedure, named QUSDRA (QUick Seismic Design of steel storage RAcks), allows designers to choose the more convenient structural solution by considering both costs and the key structural performance parameters (i.e. reduction of the load carrying capacity, transient interstorey drift and residual interstorey drift), with limited computational efforts. In fact, QUSDRA method is directly based on an IDA database which, once created, can be used for the rack design on different seismic area.
In order to better understand the key phases of the procedure, a step-by-step case study is presented, highlighting the main advantages associated with the proposed approach.

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In order to study the seismic performance of corroded steel frame structures in sulfate environment, outdoor accelerated corrosion tests and lateral low cyclic loading tests were carried out on six plane steel frame structures. Firstly, a deterioration model of mechanical property with mass loss rate for corroded Q235B steel was proposed. Then, the failure process and characteristics of corroded plane steel frame structures were observed, the effects of corrosion level and axial compression ratio on the hysteretic curves, bearing capacity, stiffness degradation, ductility and energy dissipation capacity were studied in detail. The test results indicated that in relatively slight corrosion level, all specimens exhibited a hybrid yield dissipation mechanism. However, an increase in corrosion level tended to accelerate plastic hinge formation and aggravate structural damage degree. Additionally, with the increase of corrosion level, the lateral bearing capacity reduced, stiffness degradation intensified, ductility and energy dissipation capacity decreased; with the increase of axial compression ratio, the ultimate bearing capacity, ductility and energy dissipation all decreased.

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The use of high strength (HS) steel in seismic applications is very attractive due to economical and mechanical benefits. The combined use of HSS for non-dissipative members and MCS for dissipative zones is generally termed “dual-steel” concept and it could likely represent a valuable aid to satisfy capacity design criteria and to control the global frame behaviour, even contemporarily reducing the constructional cost. The current paper investigates the benefits of applying dual-steel concept to the seismic design of eccentrically braced frames equipped with short links in the framework of EN 1998-1:2005. With this purpose, a comprehensive numerical parametric study has been carried out: both static and dynamic nonlinear analyses have been performed to investigate the advantages of using HSS to enhance strength and ductility of a set of mid- and high-rise simple and dual eccentrically braced frames.  

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Multiple earthquakes occur all over the world where challenging fault systems exist. A structure damaged by an earthquake is exposed to the risk of aftershocks within a short interval of time, which accumulates damage to the structure affecting its stiffness, strength and ductility. This study aims to investigate the response of reinforced concrete infilled frames subjected to multiple ground motion sequences. A two dimensional computational model of a mixed used RC building located in Karachi, Pakistan is developed as a bare and infilled frames for comprehensive comparative analyses. Initially, nonlinear static pushover analysis was used to estimate the capacities and damage patterns of frames. Finally, to track the complete response selected frames were subjected to three real seismic sequences (recorded at a short interval of time at same station with same direction) and four artificially generated repeated seismic sequences. Results are presented in the form of Engineering Demand Parameters (EDPs), which conforms the effects of multiple earthquakes particularly in the case of infilled frame.

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Seismic design methods based on the substitute equivalent linear elastic structure concept are based on the use of high-damping response spectra. They are being used also for the analysis of structures equipped with seismic isolation and energy dissipation systems. Damping is integrated in the response spectra using the so-called Damping Reduction Factors (DRF). It has been proposed in seismic codes to estimate high-damping response spectra from their 5% damping counterpart. The assessed structural damping value for a building over a ground motion may differ considerably from the value specified in the design. Due to the importance of damping in the structure’s seismic performance, the structural damping uncertainties should be taken on consideration in the design step.
In this paper, the damping uncertainties effects on DRFs for the estimation of high damping response spectra, are examined. Monte Carlo technique is used to describe the damping uncertainties as a lognormal probability distribution. Artificial Neural Networks (ANN) and nonlinear regression are then applied to integrate the damping uncertainties. 

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During the Northridge and Kobe earthquakes, many of steel moment-resisting frames at the beam-to-column connection were damaged due to excessive deformation.  As a solution, steel slit dampers were used in the connections to prevent the connections’ fracture and damage of the main members of the structure. In the present paper, a numerical investigation was carried out with ABAQUS software to investigate the parameters affecting the seismic performance of steel slit damper in beam-to-steel column connections. The damper specimen were simulated and verified with an experimental work under cyclic and monotonic loading. A reasonable agreement was obtained between the finite element analysis and the experimental test results. For easy expression of the damper performance criteria, monotonic loading were used by presenting the results in the form of moment-rotation.  The variables studied included the various proposed shapes for the damper, damper boosting effect, and damper thickness in the seismic performance of beam-to-steel column connection. The results show that with increasing the thickness and strengthening of the steel slit damper, the bending moment, stiffness and energy dissipation capacity of the connection, increases. Also, the new proposed slit damper had the best performance among the other dampers.

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We present a scalable approach to the design of a novel seismic isolator recently appeared in the literature, which features a unit cell composed of a central post that can slide against a base plate. Such a post carries the vertical load and is connected to four corner posts through stretchable “tendons” attached to rigid “limb” members. The bio-inspired, sliding-stretching isolator under examination is easily assembled in a fabrication lab making use of 3D-printed components and metallic parts manufactured by online and/or local suppliers. This article illustrates a scalable design approach that permits to size the components of the system according to the design values of the vertical load and the lateral displacement capacity. It is accompanied by a cost-analysis comparing the estimated cost of the proposed device with the costs of standard seismic isolators currently available on the market.

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