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Dividing walls are usually considered as non-structural elements, but experiences of past earthquakes show that some buildings designed and constructed by engineers have been damaged during earthquakes because of disregarding the negative effects of walls. Apart from the poor quality of construction and materials, inattention in design process is the main reason for undesirable seismic behaviour of walls.The main aim of this paper is to investigate the measures taken in different stages of architectural and structural design for improving the seismic behaviour of infilled concrete structures. As a general principle, with the further progress of project from basic architectural design to detailed structural design, there is a need to reduce designer authority and increase obligation, furthermore the cost of project increases too. The conclusion of this study implies that, in order to achieve the desirable seismic behaviour of walls, close collaboration between architects and structural engineers is required from the early stages of design. The results of this study are presented in a check list for designing reinforced concrete (RC) moment resisting frame and RC shear wall.

This paper presents an investigation on the structural performance of steel plate shear wall (SPSW) with flush end-plate beam–column connections and infill precast reinforced concrete (precast RC) panels. Two single-span two-story SPSW specimens, including unstiffened SPSW (NBRP) and precast RC panel restrained SPSW (Con-BRP), are first tested, followed with a parametric study by finite element method. Precast RC cover panels are installed on both sides of the infill steel plate and are disconnected from steel frame. Test results indicate that the use of precast RC cover panels increases the load carrying and energy dissipation capacities of the SPSW structure, but decreases its ductility. It is also effective in reducing the inward flexural deformation of columns. Moreover, the stiffening effect of the infill steel plate on the beam–column connections remains, which is a result of the precast RC cover panel's resistance to the local buckling and the tears of the infill steel plates. The influence of the gap size between the precast RC cover plate and frame members on the failure mode of the specimen Con-BRP is also investigated, based on which a maximum gap size is recommended. Conclusions are drawn that SPSW structure with flush end-plate beam–column connections and precast RC cover panels fully exploits the strength of infill steel plates and exhibits excellent structural performance. [ABSTRACT FROM AUTHOR]

The seismic behaviour of reinforced concrete (RC) columns made from high-strength materials was investigated experimentally. Six high-strength concrete specimen columns (1:4 scale), which included three with high-strength stirrups (HSSs) and three with normal-strength stirrups (NSSs), were tested under a combination of high axial and reversed cyclic loads. The effects of stirrup strength and the ratio of transverse reinforcement on the cracking patterns, hysteretic response, strength, stiffness, ductility, energy dissipation and strain of transverse reinforcement were studied. The results indicate that good seismic behaviour of an RC column subjected to high axial compression can be obtained by using a well-shaped stirrup. Stirrup strength had little effect on the lateral bearing capacity. However, the ductility was significantly modified by improving the stirrup strength. When loaded with a large lateral displacement, the strength reduction of NSS specimens was more severe than that of those with HSSs, and increasing the stirrup strength had little effect on the stiffness reduction. The ductility and energy dissipation of specimens with HSSs were superior to those with NSSs. When the ultimate displacement was reached, the core concrete could be effectively restrained by HSSs. [ABSTRACT FROM AUTHOR]

A series of shaking table tests were conducted on unreinforced and micropiles-reinforced soil landslides to investigate the seismic response of micropiles-reinforced landslide and the dynamic mechanical behaviour of micropiles in landslide under earthquake. The test results indicate that: (1) The micropiles can raise the anti-seismic performance of landslide, and it can efficiently delay the development of earthquake landslide hazards. (2) After earthquake, the flexural failure of micropile mainly occurs in the area that 1.4–4 times pile diameter above the sliding surface and the area that 1.4–3.4 times pile diameter below the sliding surface. (3) After reinforced by micropiles, the acceleration response on the slope surface of landslide can be decreased, especially the slope toe. (4) Both thrust of sliding mass and resistance of sliding bed are mainly concentrated near the sliding surface. The dynamic bending moment distributions of the three rows of micropiles present as reverse 'S'. The maximum bending moment of the pile above sliding surface is located at the point that 3.7 times pile diameter above sliding surface, and the maximum bending moment of the pile below sliding surface is located to the point that 1.43 times pile diameter below sliding surface. [ABSTRACT FROM AUTHOR]

• An innovative composite wall with high-strength manufactured sand concrete was proposed. • Four quasi-static tests on composite walls were conducted. • The effects of different parameters on the seismic behaviour of walls were studied. • A design approach considering the confinement effect of CFST columns is proposed. Reinforced concrete (RC) walls have been widely used in tall building construction to resist lateral loads. However, RC walls behave low ductility and limited deformation capacity under high axial force ratio. Due to the brittle behaviour of high-strength concrete, it was seldom used in RC walls though it has a vast of merits compared with normal-strength concrete. To further push up the limit of concrete strength, i.e., beyond 80 MPa in practical wall construction and to figure out a possible alternative of river sand due to the sustainability and environmental friendly requirement, an innovative wall, namely ring-stirrup concrete-filled-steel-tube (CFST) composite wall with high-strength manufactured sand concrete is proposed. The proposed composite wall consists of two CFST columns embedded at each boundary element and several stirrups in the form of continuous ring along the entire section. A series of quasi-static tests based on orthogonal experimental design method (Taguchi method) are conducted to investigate the seismic behaviour of the composite walls. The experimental parameters are axial force ratio, steel ratio in CFST columns and volume ring-stirrup ratio. From the experimental tests, it is concluded that the proposed confining schemes are highly effective in improving the seismic behaviour of the walls. Moreover, the effects of these three parameters on the peak strength, ductility and energy dissipation capacity of the walls have been investigated. Finally, a design approach considering the confinement effect of CFST columns is proposed and verified to evaluate the lateral load-carrying capacity of the proposed walls. [ABSTRACT FROM AUTHOR]

An assessment of the seismic behaviour of space mixed steel frame systems consisting of buckling restrained braced frames perimetrically and moment resisting frames internally is made by dynamic inelastic analyses. In this work 20 regular space steel frames of the above mixed type with uniaxial natural eccentricity are designed in accordance with Eurocodes 3 and 8 and subjected to 42 pairs of far-field seismic excitations. Through extensive nonlinear dynamic analyses involving four performance levels defined by their corresponding interstorey drift ratios, a seismic response databank for these frames is created in terms of displacements, maximum interstorey drift ratios, member ductilities, eccentricities and behaviour factors values. Thus, on the basis of these analyses, the seismic behaviour of this mixed type of frames is assessed and the influence of eccentricity on the response parameters examined is evaluated. • The seismic behaviour of space mixed steel frame systems consisting of buckling restrained braced frames and moment resisting frames. • 20 regular space steel frames of the above mixed type with uniaxial natural eccentricity are designed in accordance with Eurocodes 3 and 8 and subjected to 42 pairs of far-field seismic excitations. • A seismic response databank for these frames is created in terms of displacements, maximum interstorey drift ratios, member ductilities, eccentricities and behaviour factors values. • The seismic behaviour of this mixed type of frames is assessed and the influence of eccentricity on the response parameters examined is evaluated. [ABSTRACT FROM AUTHOR]

Lightweight steel framed systems (LWS) are innovative construction systems whose application has been steadily increasing over the years thanks to the huge benefits in terms of structural and environmental efficiency. Typical LWS products are usually combined with gypsum, wood and cement-based panels and can be used to build both structural and non-structural systems. After a brief description of the most common LWS constructional systems, this paper provides a state-of-the-art review of their behaviour under seismic actions. In particular, the main past and ongoing research works on lightweight steel framed structural and non-structural systems are briefly summarized and a critical comparison among seismic codes available in North America, Europe and Oceania is presented. Finally, an overview of studies carried out at the University of Naples "Federico II", Italy, on this topic is presented together with the shaking table tests carried out recently on both LWS structural and non-structural architectural systems. • Description of the most common LWS structural and non-structural constructional systems is given. • Key issues concerning the seismic behaviour of both LWS seismic resistant and non-structural systems are briefly stated. • Main past and ongoing researches on LWS framed systems are briefly summarized. • A critical comparison among seismic codes available in North America, Europe and Oceania is presented. • An overview of recent studies on LWS framed systems carried out at the University of Naples Federico II is provided. [ABSTRACT FROM AUTHOR]

This article provides the results of an experimental study on the seismic behaviour of the steel-reinforced ultra-high-strength concrete frame. A two-bay and three-story one-fourth scale steel-reinforced ultra-high-strength concrete frame specimen was tested under simulated earthquake loading conditions. The seismic behaviours of the specimen, including the failure mode, concrete element cracks development, hysteresis loops, lateral load-carrying capacity, ductility, energy dissipation, strength and stiffness degradation, were investigated under low reversed cyclic lateral loading. The test results showed that the beam hinge failure mechanism of the steel-reinforced ultra-high-strength concrete frame was achieved. The steel-reinforced ultra-high-strength concrete frame would have rich and stable hysteretic loops when subjected to large axial load with an axial load ratio of 0.38. The roof and interstory ductility coefficients of the steel-reinforced ultra-high-strength concrete frame ranged from 5.06 to 6.78. The strength and stiffness degenerated gradually, indicating an excellent seismic behaviour of the steel-reinforced ultra-high-strength concrete frame with sufficient ductility and high energy dissipation capacity. The test and analysis results can be served as a design reference for practical engineering applications. [ABSTRACT FROM AUTHOR]

Highlights • Timber panel to masonry pier screw connection for shear wall strengthening. • 64 specimens in 16 configurations tested under in-plane shear loading conditions. • Monotonic, semi-cyclic, cyclic loading protocols for seismic behaviour assessment. • Examined parameters: masonry type, timber panel, screw anchor, load-to-grain angle. • Log-normal distribution data-fitting for maximum load and slip modulus. Abstract The mechanical coupling of timber products to the masonry walls of unreinforced masonry (URM) buildings is generating considerable interest in terms of seismic vulnerability mitigation. An extensive experimental investigation on timber panel to masonry wall connections realised with screw anchor fasteners is presented. A total of 64 shear tests under monotonic, cyclic and semi-cyclic loading conditions were performed on site in a historic URM building. The examined parameters were: masonry type, timber panel product and material, load-to-grain direction, fastener geometry and steel grade. The outcomes of the campaign are then reported and discussed focusing on the strength and stiffness properties and on the dissipation capacity and residual strength of the connection under cyclic load. Moreover, a log-normal distribution fitting is proposed for the maximum load and slip modulus measurements of all the cyclic test configurations analysed. Finally, the principal experimental observations are listed along with recommendations for future work or use in practice. [ABSTRACT FROM AUTHOR]

Previous studies on the seismic behaviour of precast segmental concrete column revealed that concrete crushing and spalling damages may occur at the toes of the segments due to rocking between segments at the joints. In addition, the energy dissipation capacity of segmental column is smaller than the conventional monolithic column. Energy dissipation bars therefore have been proposed to increase its energy dissipation capability, which, unfortunately, at the cost of also increasing the residual displacement of the column, hence degrades the most advantageous characteristic of precast segmental column. To solve these problems, this paper proposes wrapping the segments with basalt fibre-reinforced polymer (BFRP) to reduce the concrete compressive damage and tension-only external energy dissipation (TEED) devices to dissipate energy without substantially increasing the residual displacement. Experimental cyclic tests and numerical simulations are carried out to examine the effectiveness of the proposed method. The results show that the damage of the segments could be effectively reduced by using BFRP, and the columns show good ductility and almost no strength degradation. The TEED devices are effective to increase the energy dissipation capacity of the column without significantly increasing the residual displacement. [ABSTRACT FROM AUTHOR]

The current study proposes a new vertical seismic isolation of an aboveground liquid storage tank (AST) and theoretically and numerically evaluates its effectiveness for a comprehensive practical range of tank geometries. In the proposed system, the forces in the vertical direction caused by the overturning moment are isolated as an alternative to the common horizontal system used for shear base isolation of ASTs. The equations of motion for a liquid tank equipped in the proposed system were extracted using the mass-spring simplified model of contained liquid. A parametric study was performed by employing the non-linear solution of the governing equations and the effectiveness of the proposed system for all AST aspect ratios is discussed. The numerical results show that the overturning moment of the tanks equipped with the proposed isolation system decreased significantly with respect to the corresponding fully anchored tanks. The results of the parametric study on the tank aspect ratio and liquid height indicate that the proposed system is more efficient for slender tanks than for broad tanks. • An innovative vertically seismic isolating of an aboveground liquid storage tank is proposed. • The method is based on the idea of separating shell dynamic motion from the base plate motion. • The Proposed method reduces the seismic responses up to 90%. • The system shows better performance for slender tanks with respect to broad ones. • The performance of proposed method is improved for stronger earthquakes. [ABSTRACT FROM AUTHOR]

One of the requirements when designing a structure in a seismic area is to choose a regular structural system, uniformly distributed in plan and elevation, in order to ensure a good seismic behaviour. The uniformly distribution on elevation leads to the reduction of possible effort concentration and ductility requirements in isolated areas of the building. In practice, there are many cases where the additional stiffness from the masonry panels led to the severe damage in the columns causing local mechanisms, respectively, until global collapse. For the case study, a mixed structural system of frames and structural walls, with irregularities in plan and in elevation, was considered. For the infill panels two materials were considered: masonry with vertical voids and autoclaved concrete. The analysis studies the stiffness increase for the considered situations and the cracks development in the linear elements of the frame. Based on the obtained results, it can be stated that the most effective solution for the infill panels of the studied structure is the autoclaved concrete. [ABSTRACT FROM AUTHOR]

Highlights • The effects of the vertical component of an earthquake on URM buildings are investigated. • Considerations on common capacity models used in seismic design are provided. • A simple façade has been analysed to evaluate the demand/capacity ratios. • Such ratios have been collected with and without the vertical component. Abstract The seismic behaviour of masonry structures is, as well-known, strongly influenced by axial stresses. During a seismic event, variations in axial loading cause in fact a change, that can be substantial, in the response in the lateral resistance capacity of masonry panels. Moreover, the axial stress can be modified by the vertical component of the seismic input during an event, which can amplify the strength variations, in particular if there is a near-fault excitation. In general, such vertical component is neglected in a traditional design. In this work, the influence of the vertical component of a seismic event is evaluated by measuring the lateral resistance of masonry piers. Such influence is estimated through a cyclic phenomenological model which calculates in an analytical way the lateral strength of a masonry panel on the base of the actual axial loading, reached step-by-step during a non-linear analysis. This model is used to simulate the cyclic behaviour of an unreinforced masonry façade made of 3 piers, having the same section for 2 floors and connected by rigid spandrels. The wall, representative of a typical masonry façade, is subjected to a series of earthquake records, with and without the vertical component of the seismic input. The differences in the responses are quantified through the use of seismic reduction factors, in such a way to satisfy the checking of the piers adopting the current design codes. [ABSTRACT FROM AUTHOR]

The connections of precast beam and column elements plays a major role in implementation of this technology in seismic regions through which the lateral stability and structural integrity will be maintained. So far the review papers published on precast beam-column connections concisely outlines the concepts, development and suitability of different form of connections in seismic regions. However review works related to seismic behaviour of different precast beamcolumn connections with analyses and discussion compared to their monolithic connection in a single platform were limited. Hence, this paper presents the overall review of the precast beam-column connection's experimental results by correlation with their monolithic connections in terms of the load carrying capacity, ductility, energy dissipation capacity, stiffness degradation and the failure mode. The different forms of connections were grouped under wet and dry connections (post-tension and mechanical device). The performances of various connection systems are analysed and compared based on the connection construction detail and seismic behaviour. Overall, the seismic performance of wet connection and post-tension connection are acceptable with some major construction drawbacks. Despite of the poor seismic performances, the mechanical device connections may be implemented in construction field with the benefit of economy and simplicity in construction. However, certain innovative ideas and or modification are to be performed to the existing systems to suit the regions of high seismicity. [ABSTRACT FROM AUTHOR]

Based on the idea of damage control, this article studied a new type of earthquake-resilient prefabricated sinusoidal corrugated web beam-column joints. First, the constitution and advantages of prefabricated sinusoidal corrugated web beam-column joints were introduced. Then, finite element models are developed based on the design theory, and the hysteretic behaviour of prefabricated sinusoidal corrugated web beam-column joints was investigated using the finite element method considering the effects of parameters such as the weakened form, thickness and unbolted length of the flange cover plate, the bolt hole form and the gap between the beams. Finally, cyclic loading test and repairing test were conducted on a basic specimen, and the rationality of the numerical analyses and the design theory were verified. It indicates that a properly designed prefabricated sinusoidal corrugated web beam-column joint has good bearing capacity and hysteretic behaviour with earthquake resilience. The thickness and unbolted length of the flange cover plate, the bolt hole form and the gap between the beams have significant effects on the seismic behaviour of the joint. [ABSTRACT FROM AUTHOR]

In order to simulate the seismic behaviour of the prestressed high-strength concrete piles under working state, six full-scale prestressed high-strength concrete piles were tested under combined axial compression and cyclic horizontal loads. Different axial compression levels and prestressing levels of prestressed tendons were studied in this test programme. The failure mode, bending resistance, displacement ductility, stiffness degradation and energy dissipation of the prestressed high-strength concrete piles under different loading scenarios were measured and analysed. Test results indicated that the axial compression ratio and prestressing level of prestressed tendon significantly influenced the seismic performance of prestressed high-strength concrete piles. Theoretical models were developed to predict cracking, yielding and ultimate bending resistances of the prestressed high-strength concrete pile under combined compression and bending. Finite element model was also developed to simulate the ultimate strength behaviour of the prestressed high-strength concrete pile under combined compression and flexural bending. The accuracies of the theoretical and finite element model were checked through validations of their predictions against the reported test results. [ABSTRACT FROM AUTHOR]

This paper presents seismic assessment of a U-shaped hysteretic damper as an enhancement system, in moment resisting frames. The proposed system is consisted of a damping box at the middle of a diagonal brace. The box includes U-shaped steel plates welded to the side plates. When a transverse load, like earthquake, is exerted to the building, relative displacement between the stories forms and will be transmitted to the braces where energy dissipation will be achieved by adding a displacement-dependent U-shaped damper. For this purpose, the system is applied to a 2D 2-span 3-story frame to which by applying eight different earthquake records, far-field, near-field and mid-field, seismic response are evaluated. The responses are the roof displacement, inter-story drifts, root mean squared of roof displacement and base shear. Result verification is carried out via calibrating characteristics of this damper with an experimental work on a somewhat similar device conducted at the University of Toronto. The results showed that by using this system, the roof maximum displacement decreased 38.9, 40.0 and 37.1% and the maximum base shear decreased 36.5, 28.5 and 39.5% respectively under near-field, mid-field and far-field records, averagely. Similar results were observed in inter-story drifts and roof displacement RMS. [ABSTRACT FROM AUTHOR]

Highlights • A replaceable damper, namely earthquake-resilient PCFBCJ, is proposed. • Several seismic behaviour indicators and failure mode of PCFBCJs are obtained. • Influence of several factors on seismic behaviour of PCFBCJs are investigated. • Replacing connection devices can achieve rapid recovery of structural functions. Abstract Based on the idea of damage control, a new type of replaceable damper, namely earthquake-resilient prefabricated column-flange beam-column joint (PCFBCJ), is proposed in this paper. In order to study its seismic behaviour and post-earthquake resilience performance, five specimens were designed and six low frequency cyclic loading tests were conducted. Through these series of tests, several seismic behaviour indicators such as hysteresis curve, strain curve, skeleton curve, and energy dissipation of the joint could be obtained. Finally, the test results were verified by finite element method. This study mainly investigated the influence of several factors, such as the thickness of the flange cover plates, the number of flange bolts, the gap between the beams, and some other parameters on seismic behaviour and post-earthquake resilience performance of this joint. The results of the tests showed that this new PCFBCJ had excellent load resisting capacity, ductility and post-earthquake resilience performance, and the repaired joint could still meet the requirements of seismic behaviour; the thickness of the flange cover plates directly determined the yield load of the joint, and the reasonable gap between the beams could effectively avoid premature compression between the beams and plasticity of main components; the number of flange bolts directly affected the slippage of flange cover plates; the PCFBCJ had a stable hysteretic behaviour during loading with constant amplitude, therefore it can also be used as a damper. The refined finite element results matched the test results well, therefore, the refined finite element model could be used as an effective tool to study the performance of such joint. [ABSTRACT FROM AUTHOR]

Highlights • Drift in CBFs designed to EC8 is dependent on mean ground motion period. • Increased drifts when ratio of mean period to fundamental structural period is low. • In these cases numerically calculated drifts can exceed values predicted by codes. • Regression models developed to peak predict global and inter-storey drift in CBFs. Abstract The influence of mean ground motion period, T m , on the inelastic drift response of steel Concentrically Braced Frame (CBF) structures designed to Eurocode 8 is investigated. Incremental dynamic analysis is performed for a set of case study frames with varying structural characteristics at four different seismic intensity levels. From the results of these analyses, regression models for predicting both global and inter-storey drift are developed. It is shown that that both global and inter-storey drift tend to increase nonlinearly as the ratio of fundamental structural period to mean ground motion period, T 1 / T m , decreases below unity. The rate of this increase is dependent on the ground motion intensity, represented by the EC8 behaviour factor q. The first mode participation factor, relative storey stiffness and column-to brace stiffness are also shown to influence inter-storey drift response. The values of drift predicted by the developed regression models are compared to values predicted by design codes as well as other predictive models developed in previous studies. It is observed that design codes can under predict drift at lower T 1 / T m values. [ABSTRACT FROM AUTHOR]

• Elliptical concrete-filled FRP tubes with an embedded H-shaped steel (i.e., HS-ECFFTs) were tested under axial compression and cyclic lateral loading. • HS-ECFFTs performed with remarkable energy dissipation ability. Due to the effective FRP confinement, the local buckling of H-shaped steel was prohibited. • The elliptical aspect ratio had limited influences on the ductility, the stiffness degradation and the energy dissipation behavior. • The FRP thickness, after a certain threshold, showed beneficial but limited influences on the peak load, the stiffness degradation and the energy dissipation behavior. Concrete-filled FRP tubes (CFFTs) have found increasing applications due to their superior ductility and remarkable corrosion resistance. In published literature, circular CFFTs and rectangular CFFTs have been investigated extensively, while there are relatively few studies on elliptical CFFTs. There is no research about elliptical CFFTs with an embedded H-shaped steel (i.e., HS-ECFFTs) under axial compression and cyclic lateral loading. Against this background, this paper investigated the seismic behaviour of HS-ECFFTs experimentally and numerically. Test results indicated that: (1) all HS-ECFFTs performed well with remarkable energy dissipation ability; (2) due to the effective FRP confinement, the local buckling of the H-shaped steel was prohibited; (3) the elliptical aspect ratio had limited influences on the ductility, the stiffness degradation and the energy dissipation; (4) the FRP thickness, after a certain threshold, showed beneficial but limited influences on the peak load, the stiffness degradation and the energy dissipation; (5) the HS-ECFFT specimen performed much better in terms of the peak load, the ductility, the stiffness degradation and the energy dissipation when it was bending around the strong axis. The proposed numerical model established on the OpenSees platform could generate reasonably accurate numerical results for all HS-ECFFTs. [ABSTRACT FROM AUTHOR]

Special composite RC shear wall (CRCSW) with steel boundary elements is a kind of lateral force resisting structural system which is used in earthquake-prone regions. Due to their high ductility and energy dissipation, CRCSWs have been widely used in recent years by structural engineers. However, there are few studies in the literature on the seismic design of such walls. Although there are many studies in the literature on the Direct Displacement-Based Design (DDBD) of RC structures, however, no study can be found on DDBD of CRCSWs. Therefore, the aim of present study is to evaluate the ability of DDBD method for designing CRCSWs. In this study, four special composite reinforced concrete shear walls with steel boundary elements of 4, 8, 12 and 16 story numbers were designed using the DDBD method for target drift of 2%. The seismic behavior of the four CRCSWs was studied using nonlinear time-history dynamic analyses. Dynamic analyses were performed for the mentioned walls using 7 selected earthquake records. The seismic design parameters considered in this study includes: lateral displacement profile, inelastic dynamic inter-story drift demand, failure pattern and the composite RC shear walls overstrength factor. For each shear wall, the overall overstrength factor was calculated by dividing the ultimate dynamic base shear demand (Vu) by the base shear demand (Vd) as per the Direct Displacement Based-Design (DDBD) method. The results show that the DDBD method can be used to design CRCSWs safely in seismic regions with predicted behavior.

The paper analyzes different wooden buildings types used in past and nowadays to realized low-rise and mid-rise timber structures from the seismic point of view. A preliminary overview about the procedures prescribed by codes for the seismic characterization of the timber building systems is given. Then the definition of the behaviour q-factor in the literature and its relevance in design of structures in seismic areas is treated. Available research methods for estimating the q-factor based on the verification of the nonlinear seismic response of entire buildings by means of experimental tests and numerical simulations are presented and analyzed. The relevance of a proper definition of the yielding limit and of failure condition in the seismic characterization of wooden building systems is treated. Moreover, a comparison between the q-factor estimations obtained using different calculation methods is presented. Lastly, the appropriate q-factor values are given for a reliable and safe seismic design of buildings realized using the examined wooden constructive systems.

Preservation of historical constructions, and passing it on to future generations, is a major issue in modern societies. Earthquakes are one of the major causes of damages to heritage buildings across the world. The city of Sobral (Ceará State, Brazil) keeps in its historic center a large number of heritage buildings and, since 2008, an intense seismic activity has been observed. This study aims to contribute to the preservation of the Sobral heritage constructions against seismic loads through the assessment of the seismic behavior of one representative building: the Nossa Senhora das Dores Church, a 19th century historical construction. First, a 3D finite element (FE) model was built and tuned according to the results of dynamic tests performed under environmental loads. Next, the FE model was employed to assess the seismic behavior of the church by performing linear time-history analyses employing two real earthquakes. The results showed big displacements and high stresses in many parts of the church, allowing to identify the most critical and most susceptible to damage areas (based on the seismic scenarios considered). These results can be considered as a support for seismic retrofitting measures to be adopted on Sobral heritage constructions.

This article aims to investigate the seismic performance of a four-tower (frame-shear wall) building with a large frame podium at bottom sitting on a metro depot through shaking table test and numerical simulations. Technical problems generally exist in this type of buildings due to irregularity in elevation and plan, tower offset, and structural transfer. These problems bring challenges to engineers when analysing and predicting dynamic responses under earthquakes which is crucial for structural safety. To evaluate the seismic performance of the building, a comprehensive study which includes a shake table test of the scaled model and time history analyses using a finite-element model is conducted. The shake table test model is designed based on the similitude law with a 1:40 scale. The dynamic characteristics, cracking pattern, failure mechanism, as well as maximum acceleration and deformation response are investigated. The corresponding finite-element analysis shows a good agreement with experimental results. It is concluded that this type of building can achieve the predefined performance objectives with well-behaved transfer floors. Shear failure at weak story is considered as a main failure mode of the structure. The whipping effect of stories on the top of structure is remarkable. There is no severe damage in steel reinforced concrete beams. Finally, some design suggestions are also proposed to improve the seismic performance of this type of buildings. [ABSTRACT FROM AUTHOR]

In the areas under high earthquake risk, the impact of fire damage on the seismic performance of the reinforced concrete (RC) structures ought to be realistically taken into account while assessing the fire damage to develop reuse/repair/replace strategies through the remaining service life. In the scope of this study, a literature review is conducted on the changes of mechanical characteristics of concrete and reinforcement caused by a fire with a particular emphasis on the post-cooling stage. Post-cooling behaviour of RC members is different than the behaviour under elevated temperatures and hence it is of vital importance on structural seismic performance assessment after a fire. Apart from material-wise assessment methodologies, post-fire seismic performance of RC structural members is also discussed through post-fire simulated seismic loading tests conducted on full-scale cast-in-place and precast columns. The test results pointed out to a reduction in lateral load bearing capacity of the cast-in-place columns subjected to fire whereas fire-exposed precast columns demonstrated better performance in terms of residual lateral load capacity due to the lower axial load and larger heights. All columns exhibited satisfactory performance in terms of ductility. [ABSTRACT FROM AUTHOR]

Highlights • A novel DSC shear wall with overlapped headed studs was developed. • Seismic behaviours of DSC shear wall were studied through quasi-static tests. • Effects of parameters on seismic behaviour of DSC shear wall were evaluated. • Theoretical models were developed for flexural resistance of DSC shear wall. Abstract This paper proposes a type of double skin composite (DSC) shear walls with boundary columns to make solutions to improve ductility of high-rise buildings. In this DSC shear wall system, overlapped headed studs were used to achieve composite action between the steel face plate and concrete core. Seven DSC shear walls were tested under combined axial compressive force and horizontal cyclic loads to evaluate the seismic behaviours of this DSC shear wall. Key parameters in this test program include height of overlapped headed studs, axial force ratio, introducing steel tubes in boundary columns, and aspect ratio of the DSC shear wall. The test results exhibited that the tested seven specimens failed in flexure mode characterized by local buckling of steel face plate, tensile fracture of steel boundary column, and concrete crushing. Test results also show that using higher headed studs in DSC shear walls improved their deformation capacity and energy dissipation capacity. Increasing axial force on the DSC shear walls did not compromise their energy dissipation capacities but slightly reduced their ductility. Introducing steel tube in the DSC shear walls significantly improved the ultimate resistance, ductility, and energy dissipation of the DSC shear walls. Decreasing the aspect ratio from 2.0 to 1.0 nearly doubles the ultimate resistance and energy dissipation capacity of the DSC shear walls. Theoretical models were also developed to predict the ultimate load carrying capacity of the DSC shear walls under horizontal loads. The validations of the predictions by the developed analytical models against 14 test results confirm the accuracy of the developed theoretical models. [ABSTRACT FROM AUTHOR]

This paper proposes the use of sleeve joints for the steel connection of concrete-filled, square, tubular columns to H-beams. To study the influence of the sleeve height and thickness, three joint specimens were designed and subjected to low-cycle loading tests. The effect of these size parameters is evaluated in terms of specimen stiffness, load-bearing capacity, energy dissipation capacity, ductility performance and shear deformation of the joint. The experimental results show that under the reciprocating load, the ultimate failure modes of the connection are tearing of the joints at the beam-sleeve interface and the welded column-sleeve interface. Increased sleeve thickness significantly increases the bearing capacity, stiffness, energy dissipation capacity and ductility of the members and joints, by reducing the strength degradation and stiffness degradation of the members. The joint strength and stiffness degradation is stable, with good ductility and energy dissipation capacity that meets seismic requirements. [ABSTRACT FROM AUTHOR]

Seismic behaviour of masonry buildings, built of low compressive strength units, is discussed. Although such materials have already been tested and approved for use from mechanical and thermal insulation point of view, the knowledge regarding their structural behaviour is still lacking. In order to investigate the resistance and deformation capacity of this particular type of masonry construction in seismic conditions, a series of eight walls and model of a two-storey full scale confined masonry building have been tested by subjecting the specimens to cyclic shear loads. All tests were conducted under a combination of constant vertical load and quasi static, cyclically imposed horizontal load. The behaviour of tested specimens was of typical shear type. Compared with the behaviour of plain masonry walls, the presence of tie-columns resulted into higher resistance and displacement capacity, as well as smaller lateral resistance degradation. The response of the model was determined by storey mechanism with predominant shear behaviour of the walls and failure mechanism of the same type as in the case of individual confined masonry walls. Adequate seismic behaviour of this particular masonry structural type can be expected under the condition that the buildings are built as confined masonry system with limited number of stories. [ABSTRACT FROM AUTHOR]

Cultural heritage constitutes a fundamental resource for a country, both in terms of cultural identity as well as tourist attraction. This is particularly true for Italy, where earthquakes have severely damaged monumental buildings and historical centres in the past, causing huge losses and requiring great efforts for the interventions. The 1976 Friuli earthquake was the starting point for a new, observational-based approach to the vulnerability analysis of historical buildings, and in particular to churches and bell-towers. This new approach enabled interpreting the mechanisms of damage and identifying the weakness points for a more effective and focused intervention of retrofitting. This paper presents a brief overview of how the 1976 Friuli earthquake experience contributed both to the knowledge of seismic behaviour of historical buildings and to the formulation of tailored safety upgrading projects. [ABSTRACT FROM AUTHOR]

Highlights • DEM to investigate the in-plane seismic behaviour of rammed-earth walls. • A real earthquake excitation was applied to the model. • Excitation was scaled at different amplitudes to assess the damages. • For excitations lower than 2.3 m/s2, rammed-earth walls had satisfying performance. Abstract Rammed earth (RE) is a construction material which is manufactured by compacting the soil within a formwork, in superimposed layers. RE is attracting scientific studies because of its sustainable properties : a very low embodied energy and an advantageous living comfort due to a particular benefic hygro-thermal behaviour. Numerous studies have been conducted to investigate RE material and RE structures, however, a lack of knowledge on the seismic performance of RE buildings is noticed. This paper presents an advanced numerical study to investigate the in-plane seismic behaviour of RE walls. First, a numerical model of an in-situ RE wall was constructed by using discrete element modelling (DEM). The relevancy of the numerical model was verified by comparing dynamic properties of the model with that measured on the in-situ wall. Then, a real earthquake excitation was applied to the model, in order to evaluate the seismic performance of the RE wall studied. This is the first time, to our knowledge, that a dynamic discrete explicite analysis was performed for a RE wall. The excitation was scaled at different amplitudes to assess the damages following different earthquake intensities. The results showed that for seismic excitations lower than 2.3 m/s2, RE walls studied had satisfying in-plane earthquake performance. [ABSTRACT FROM AUTHOR]

This paper investigates the in-plane seismic behaviour of hinged steel frames that are enhanced with masonry columns and/or infilled walls. First, eight half-scaled hinged steel frame specimens were constructed according to the realistic structural system of Bund 18, which is a historical building in Shanghai, China. Then, cyclic loads were exerted on these frames. The test results indicated that the seismic behaviours of the hinged steel frames can be significantly improved with the use of masonry columns and/or infilled masonry walls as well as with proper strengthening due to carbon fibre-reinforced polymer (CFRP) sheets. A simplified model was developed to simulate the seismic behaviours of these frames. In this model, infilled walls and CFRP sheets were replaced by diagonal struts, and the steel members and their surrounding elements were treated as composite members. Finally, this model was verified by experimental results. [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) flat slab column structure is a typical vertical support system and is often used in regions of moderate seismicity. Additionally, a steel structure is easy to assemble and exhibits good mechanical property, ductility and energy dissipation performance. Thus, this study presents a new type of connection between a prefabricated RC flat slab and square steel tube column. The connection effectively improves seismic performance and stress mechanism and leads to plastic deformation in the cantilever beams that can be replaced after an earthquake. The connection consists of a column base with four cantilever beams, a channel steel connection, and an RC flat slab. A gap connected by four square crossing I-steel cantilever beams is left between the column and channel steel connection, and this forms an opening around the column. An experiment was performed to study the seismic behaviour of the prefabricated slab column connection. The effects of the key parameters including the I-steel web thickness of the cantilever beam and axial compression ratio were investigated. The failure modes, hysteretic curves, and stress–strain curves with respect to relevant components were presented. A numerical simulation verified by the tests was performed to analyse the section stress and bolt forces for making up the test deficiency. The results indicated that the prefabricated slab column connection exhibits a superior seismic performance, thereby leading to earthquake-resilience. Finally, design considerations were presented to guide engineering practice for the proposed prefabricated slab column connection. [ABSTRACT FROM AUTHOR]

In event of severe earthquakes RC structures are subjected to lateral jolts. The behaviour of the structures towards seismic forces is dependent on the structural composition and lateral stiffness. Elevated water tanks supported on shafts are inverted pendulums with heavy mass suspended at the top. While chimneys are stack like structure whose structural composition is like a slender cantilever fixed at the base. In this paper an attempt shall be made to critically compare the lateral seismic behaviour of these two different structures using equivalent static and dynamic analysis procedure. The selection of the two classes of structures has been done from the logic that the RC shaft of an elevated water tank resembles a chimney of low height loaded with heavy load at the top. Whereas chimney being a more slender structure, both these structures falls in different natural period ranges of the design spectra and hence they attract different levels of seismic forces. The paper proposes to compare critically the variation in seismic behaviour of these two classes of structures, which is elevated water tank on shaft a relatively rigid period system and chimney a rather longer period system. [ABSTRACT FROM AUTHOR]

Over the last years, the seismic behaviour of infilled reinforced concrete (RC) structures has been the focus of innumerable experimental and numerical studies. A big effort is being made by the scientific community to increase the knowledge regarding the seismic performance of these types of structures and to improve the numerical modelling capabilities to predict their expected behaviour accurately. In 2015, a blind prediction contest was organized by the Faculty of Civil Engineering, University of Osijek, with the main goal of inviting the technical and scientific community to predict the nonlinear seismic behaviour of a 1:2.5 scaled 3D building structure. A three-storey infilled RC structure was subjected to a sequence of ten incremental earthquakes in a shake table test. The blind numerical simulations were carried out by different international teams invited by the organizational committee. The teams knew only the specimen geometry, reinforcement detailing, material properties, and ground motions recorded during the testing. In this context and, in the light of the authors’ success in the contest, the present paper mainly aims at presenting several issues regarding the numerical modelling strategies adopted (and related difficulties) which proved to yield good results while also providing some insight regarding key problems in numerical simulations of infilled RC structures under seismic actions. The main numerical results obtained by all of the participating teams will be presented and compared with the experimental ones. Discussion concerning the reasons behind the mismatching of some results will be presented. Finally, a parametric study was carried out with the aim of assessing the influence of some modelling issues and parameters on the structural global response, in particular when affected by some variations. [ABSTRACT FROM AUTHOR]

To improve the strength and ductility of the core walls in high-rise buildings which would be subjected to combined high axial compressive force and bending moment during the earthquake, an innovative concrete filled double-skin steel-plate composite (CFDSC) wall is proposed. The CFDSC wall is composed of the concrete filled double-skin steel-plate wall body with transverse stiffeners, vertical diaphragms and distributed batten plates welding on the internal surface of the double steel plates, and the concrete filled steel tube (CFST) columns including a pair of CFST columns positioned at the end of the cross section as boundary elements and an additional one located in the central section of the wall. Five CFDSC wall specimens were tested under constant axial compressive force and lateral reversed cyclic loading to investigate the seismic behaviour of the wall considering the effect of axial force ratio and shear span ratio. The favourable seismic performance of the CFDSC walls was demonstrated in the test. No serious pinching effect was observed on the hysteresis curves of all the specimens. The drift ratios corresponding to the ultimate stage were recorded as being in the range from 1/67 to 1/30 and the ductility coefficients were varied from 4.50 to 8.22. The experimental results manifest that the CFDSC walls have great energy dissipation capacity. Formulae for calculating the lateral load-carrying capacity of the CFDSC wall, taking the confinement effects from steel plates into account, were proposed. The results calculated by the proposed method show good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Dry connections are widely used in precast structures for their reduced dimensions and faster installation than wet cast-in situ joints. Above all, column-to-footing and column-to-column dry joints represent a very effective alternative to conventional monolithic solutions for columns higher than three storeys, whose transportation and installation turn out to be too much complicated or unfeasible. A wide and safe use of dry joints in precast columns asks for an in-depth analysis of their behaviour, as both their density and technology affect the overall performance of precast structures, especially under seismic loading. The paper shows results of an experimental campaign performed on full-scale specimens to investigate the behaviour of dry connections for precast columns, under both static and cyclic loading. Tests were performed on two types of joints: in the first type the flexural continuity is achieved by welding column’s longitudinal bars to its steel base plate, while in the second type column’s longitudinal bars are overlapped with sufficient length to rebar dowels welded to the steel column base plate. Experimental results show a good performance of investigated joints, in terms of both overstrength and stiffness. Moreover, the ductility and energy dissipation properties of the column’s region adjacent to the joint were evaluated. [ABSTRACT FROM AUTHOR]

The results of in-plane static cyclic lateral loading tests conducted on unreinforced masonry walls retrofitted with trowelling engineered cementitious composites (ECC) are presented in this paper. Six 1/2 scale testing specimens including unretrofitted and retrofitted walls were constructed. The first and second unretrofitted masonry walls were control specimens. The third and fourth walls were retrofitted applying ECC with strip type and the other two walls were retrofitted with ECC coatings. Every batch of tested walls was constructed with two different mortar strengths. The failure modes, lateral strength, ductility, stiffness, and the energy dissipation capacity of the tested walls were examined and compared. Furthermore, the experimental envelope curves were idealized and reasonable overstrength factors of the retrofitted walls were obtained. The results indicated that these retrofit techniques can effectively improve the lateral strength and the displacement ductility of unreinforced masonry (URM) walls, convert the brittle failure mode to a more ductile one, and provide an effective constraint for the walls, resulting in preserved integrity of the wall at large lateral displacements. Finally, the calculation methods for each retrofitting scheme were proposed to estimate the ultimate lateral strengths of ECC retrofitted masonry walls. [ABSTRACT FROM AUTHOR]

The coupled steel plate shear wall (C-SPSW) configuration consisting of two SPSWs linked by coupling beams at the floor levels, in addition to providing architectural flexibility, has been shown to exhibit superior seismic performance. While the shear strength of the infill panels due to tension field action is the primary source of lateral load resistance in a C-SPSW, the moment resisting actions of the boundary frames and the coupling beams connections provide substantial strength for the system. As such, in order to achieve material-efficient designs, rational procedures are needed to explicitly account for this strength, while maintaining the desirable performance for various hazard levels. Similar to planar SPSWs, the C-SPSW systems have been designed using the conventional force-based design approach, which typically requires several iterations to optimize the design for performance and efficiency. This research employs the principles of plastic analysis to quantify the contribution of the frame action to the overall strength of C-SPSWs and adopts the philosophy of the performance-based plastic design (PBPD) methodology to develop procedures for the efficient seismic design of such systems. To investigate the effectiveness of the proposed design procedure, 8- and 12-story case study C-SPSWs were designed, and their numerical models were analyzed using pushover and response history analyses. The seismic performance of the prototypes were evaluated using two suits of ground motions representing 10/50 and 2/50 hazard levels. The analysis results indicated that the C-SPSWs designed using the proposed approach successfully met the desired performance objectives for both seismic hazard levels considered. [ABSTRACT FROM AUTHOR]