Good Seismic Performance Research Articles

Structural fuse performance and earthquake-resilient performance of beam-column joints with replaceable T-stub

In order to ensure that steel frame systems have excellent structural fuse performance and earthquake-resilient performance on the basis of good seismic performance, a novel steel beam-column joint with replaceable T-stub connection components (SBCJ-RTCCs) was proposed. The pseudo-static cyclic tests of original and replaced specimens were carried out. As an extension of the experimental tests, numerical parametric analyses were performed to determine an optimal range of resistance capacity ratio to make a balance between the seismic performance, structural fuse performance and earthquake-resilient performance. The analysis results demonstrated that despite seismic performance of specimen with a small resistance capacity ratio is relatively weak, the structural fuse performance and earthquake-resilient performance performed well. With the increase of resistance capacity ratio, the seismic performance consisting of initial stiffness and bearing capacity gradually improved. However, the plasticity and damage would be shifted from RTCCs to non-fuse components, which adversely affected the structural fuse performance, despite the earthquake-resilient performance of specimen was still good. In terms of comprehensive consideration of seismic performance, structural fuse performance and earthquake-resilient performance, the resistance capacity ratio was suggested as 0.53–0.63. Moreover, a design procedure of SBCJ-RTCCs was proposed, and its rationality was validated by a design example RT-D. The result indicates that by adopting the proposed design procedure, the RT-D exhibited stable hysteretic behavior without experiencing strength degradation. The RTCCs can play the role of structural fuses by dissipating more than 90% of the input energy, which effectively protect the non-fuse components from damage.

Seismic performance of cruciform bolted joints with various reinforcing details in modular steel construction

Extensive research has been done on exterior T-shaped joints of modular structures. The modular structure consists of stacked modules that are not only connected vertically but also need to be connected horizontally. The horizontal connection between modules is another key for the modules to form an integral structure and resist lateral forces. This paper proposes a novel bolted joint that can be applied to multi-column module internal and external connections. By designing special loading supports, three internal cruciform joints and three external cruciform joints of the modular structure were tested under column end loading. The effects of different strengthening measures and the ratio of beam to column flexural bearing capacity on the seismic performance of the joints were compared. The results showed that all the joints had good seismic performance and satisfied the requirements of SMF systems in terms of inter-story drift ratio. The stiffness and bearing capacity of the internal joints after the beam-beam combination increased by 33.2% and 17%, respectively. However, the stiffness and bearing capacity of the cruciform joints strengthened by the cover plate are not significantly improved. For joints that meet the conditions of strong columns and weak beams, modular beams can reach full-section plasticity and can meet the requirements of full-strength joints.

Seismic Performance of Concrete Column Connection with Square-Upper-Circular-Lower Steel Tube for Antique Buildings

The antique building combines traditional design with contemporary technology, making it an important structural style. Columns, as a crucial structural component, directly affect how well the building functions as a whole. This paper proposes a new connection form with the upper square concrete-filled steel tube-lower circular concrete-filled steel tube (USCFST-LCCFST). This study investigates the seismic performance of the proposed connection form of the columns. First, the finite element software ABAQUS-2021 is used to simulate and analyze the connection forms of the upper square concrete-filled steel tube and lower circular reinforced concrete (USCFST-LCRC) and the upper square steel reinforced concrete and lower circular reinforced concrete (USSRC-LCRC) above the antique building, respectively, which confirms the rationality of the modeling method explored in this paper. Then, geometric modeling of the USCFST-LCCFST connection is performed using ABAQUS. Simulation results demonstrate the superior seismic performance of the proposed connection form. In addition, the influence law of steel tube yield strength and the ratio of upper and lower column linear stiffness on its seismic performance are analyzed and determined through the variational parameter analysis of the USCFST-LCCFST connection form. The steel tube yield strength of USCFST-LCCFST column connection components is recommended to be 355–420 MPa and the ratio of upper and lower column linear stiffness should be no less than 0.063. In order to ensure the good seismic performance of the connection, the steel tube yield strength and the ratio of upper and lower column stiffness should be efficiently controlled in the design of antique buildings’ USCFST-LCCFST column connection components.

Genetic algorithm model of PEC column-steel plate shear wall with flush end-plate joints based on component method

The partially encased concrete (PEC) column-steel beam frame steel plate shear wall (SPSW) structure of semi-rigid joint has good cooperative working performance and seismic performance. In this paper, based on the EC3 component model, considering the contribution of the new concrete components in the PEC column to the initial rotational stiffness of the joint domain, the component model of the flush end-plate PEC column joint was established. A 1/3-scale two-story single-span flush end-plate PEC column-steel beam frame SPSW structure was tested under quasi-static cyclic loading. The OpenSees model of this structure was established, which was validated by test results. Parametric analysis of the additional damping ratio for semi-rigid joints was conducted using OpenSees. The suggested value of additional damping ratios for semi-rigid joints was given. Finally, based on Matlab and OpenSees, the model was input in the form of tool command language (TCL), an optimal arrangement model of flush end-plate PEC column joints with the genetic algorithm (GA) as the main procedure was designed. The effects of different arrangement schemes of semi-rigid joints on the seismic response of PEC column-steel beam frame SPSW structures were analyzed. The results show that the seismic performance of the flush end-plate PEC column-steel beam frame SPSW structures is reliable. The results of the finite element (FE) are in good agreement with the test results, which indicates that the established OpenSees model is effective. The contribution of the new concrete components to the initial rotational stiffness of the middle joints, top and bottom joints is 45.02% and 49.68%, respectively. The optimal arrangement scheme of semi-rigid joints can be efficiently computed by the proposed GA model.

Study on the Bearing Capacity of Steel Formwork Concrete Columns

Steel formworks are widely used in prefabricated buildings thanks to their good characteristics. With the rapid development of engineering construction in China, steel formwork concrete structures, characterized by convenient construction, good seismic performance, and high strength, are expected to be more extensively applied in engineering practice. However, the bearing capacity of different forms of steel formwork concrete is still unclear. Two prefabricated columns with different internal diaphragm styles were set up for axial compression tests to investigate the performance of steel formwork columns. This study conducts monotonic static loading tests on six prefabricated steel tube column specimens and performs finite element analysis by taking steel tube thickness, rebar diameter, and internal diaphragm style as the influencing parameters. The results show that the prefabricated specimens can work in the test process, and the ultimate bearing capacity is consistent between the tests and numerical simulation. Moreover, the nephograms obtained from numerical simulation also conformed to the failure mode of the specimens in the test process. Therefore, the finite element model proposed in this study can accurately predict the stress performance of steel formwork concrete stub columns. These results offer guidance for future engineering practices.

Longitudinal Seismic Analysis of Tunnels with Nonuniform Strata Considering the Effect of Karst

The longitudinal direction of shield tunnels is prone to seismic damage due to excessive deformation under seismic action, especially in nonuniform stratum. In this paper, the longitudinal dynamic response of the tunnel under different seismic effects is calculated based on the longitudinal equivalent stiffness model using the stratigraphic load model, and the seismic indexes such as longitudinal corner, tube sheet and joint bolt stresses are verified. The calculation results show that the longitudinal seismic weakness of the shield tunnel is in the interface between soft and hard strata and karst development. The longitudinal axial force of the structure is larger during the longitudinal excitation of seismic waves, and the maximum bending moment is mainly in the vertical plane, i.e., the vertical bending moment. The axial force of the tunnel is smaller during the transverse excitation of seismic waves. The maximum bending moment is mainly the bending moment in the horizontal plane, i.e., the transverse moment. The South Lake section of the Two Lakes Tunnel has good seismic performance in the event of a rare earthquake with a 50-year exceedance probability of 2%. The investigation can guide the seismic design of the South Lake section of the Two Lakes Tunnel.

Seismic performance of the intermediate unit of a scrap tire–granular material composite column

ABSTRACT This study focused on the seismic performance of an intermediate unit of scrap tire–granular material composite columns under cyclic loading. A Laboratory test study regarding the dynamic deformation characteristics of the intermediate unit of a scrap tire–granular material composite column was conducted. The hysteresis loops, skeleton curves, stiffness degradation curves, and energy–dissipation capacities of the three specimens with different initial vertical loads were experimentally evaluated. Based on the test results, a restoring force model of the tire–granular material unit is established. The results demonstrated that the external force had a significant influence on the strength of the intermediate unit of the scrap tire–granular material composite column. The area of the hysteresis loop of the tire–granular material unit was large, indicating a good seismic performance. As the initial vertical load increased, the horizontal bearing capacity and lateral stiffness of the intermediate unit of the scrap tire–granular material composite column increased. The calculation results of the skeleton curve and hysteresis curve were in good agreement with the test results. As a base damping material, the scrap tire–granular material composite column is feasible, and provides a new concept for the resource utilization of the original scrap tire.

Horizontal residual displacement of reinforced soil retaining wall under seismic forcing

As a new type of flexible retaining structure, reinforced soil retaining wall is widely used in civil engineering and highway engineering because of good seismic performance and economy. The residual displacement under seism is one of the most important parameters to evaluate the seismic performance of reinforced soil retaining wall. The related theoretical research is rare. Taking the pseudo-dynamic method and kinematic differential equation as the theoretical basis, considering the residual deformation under large magnitude, a theoretical method is proposed to calculate the residual displacement of reinforced soil retaining wall under seismic. The rationality and accuracy of the theoretical method is verified by centrifuge model test. The results would provide some reference for the performance design and damage evaluation of reinforced soil retaining wall.

SEISMIC PERFORMANCE OF PREFABRICATED CORE STEEL TUBE REINFORCED CONCRETE COLUMNS

AbstractPrefabricated assembly accelerates the building construction process. A primary concern related to prefabricated assembly is the increased fragility of the connection between precast members compared to cast‐in‐situ members. On the other hand, core steel tube reinforced concrete (CSTRC) columns are increasingly being used in high‐rise structures to provide effective axial and lateral force resistance. This study proposes a prefabricated core steel tube reinforced concrete (PCSTRC) column which capitalizes on both the strength of the CSTRC column and the advantages of precast manufacturing, as shown in Fig. 1. The connection is designed to guarantee the integrity of the whole column. Two full‐scale PCSTRC columns with varying axial loads and two controlled specimens, namely a monolithic CSTRC column and a conventional reinforced concrete (RC) column, were fabricated and tested under quasi‐static cyclic loading in order to investigate their seismic performance. The test results demonstrate that all the columns experienced typical flexure‐controlled failure, while the PCSTRC columns suffered less visual damage than the monolithic controlled specimens. The PCSTRC column performed satisfactorily in terms of strength, stiffness, ductility, and general hysteretic behavior and had significantly greater load‐carrying and energy dissipation capacities than the conventional RC column. In addition, there were no apparent differences between the capacities of the CSTRC and PCSTRC columns. As axial load increased, the deformation capacity of the PCSTRC column decreased. Overall, the proposed prefabricated composite column demonstrates good seismic performance and can be considered for use in building construction.

Numerical Investigations on Seismic Behavior of Segmental Assembly of Concrete Filled Steel Tube Piers with External Replaceable Energy-Dissipating Links.

In order to reduce the damage sustained by the substructure of bridges during an earthquake, reduce economic loss, avoid casualties, and ensure the quick repair of bridges after an earthquake, this paper, inspired by the good seismic performance of the rhombic opening in the shear wall structure, proposes a precast segmental concrete-filled steel tubular (PSCFST) pier with external replaceable energy-dissipating links (EREDL).Through finite element simulation analysis, it can be found that the energy dissipation capacity of a PSCFST pier with external EREDL is increased by 104% compared with that of a PSCFST pier without EREDL, and the lateral bearing capacity is increased by 76.9%. Through parameter analysis, it can be found that the change of initial prestress has little effect on the energy dissipation capacity of PSCFST piers, and the seismic performance of PSCFST piers can be improved by properly increasing the ultimate tensile strength of the energy dissipator materials. Compared with the energy dissipators made of Q235 steel, the energy dissipation capacity of PSCFST piers made of Q435 steel energy dissipators is increased by about 85.4%; At the same time, the thicker the energy dissipator, the stronger the energy dissipation capacity of the PSCFST pier, and the lateral bearing capacity is further improved.

Experimental and Numerical Studies on the Seismic Performance of New Assembled Concrete Frame Beam–Column Joints

A new type of assembled concrete beam–column joint based on a bolted connection was proposed, aiming to complete the post-earthquake node repair work by replacing precast beams and bolts. To study the seismic performance of the new beam–column joints, two full-scale components of the new joints were fabricated and subjected to low cyclic loading. The whole process from crack generation to component failure was investigated in detail, and seismic performance indicators such as the hysteresis curve, skeleton curve and stiffness degradation curve were compared and analyzed. Based on the experimental results, ABAQUS finite element software was applied to numerically simulate cast-in-place joints and test joints. Based on the failure mechanism of the new assembled beam–column semi-rigid joints, a stress analysis of semi-rigid joints was carried out. The research results show that the two new joints have good seismic performance and energy dissipation performance. Bolts and precast beams are the main stress components, and the repair of new joints can be completed by replacing bolts, which meets the seismic design concepts of “strong columns and weak beams” and “strong joints and weak components”. The larger the diameter of the bolts, the higher the load capacity and the lower the stiffness degradation rate. The finite element simulation results are high-accuracy and can well reflect the seismic performance of the components. It is found that cast-in-place joints are better in energy dissipation capacity than test joints, but the ultimate bearing capacity of test joints is better than that of cast-in-place joints. Based on the experimental stress characteristics of the nodal core zone, a mechanical analysis model of the nodal core zone of the new assembled concrete beam–column joints is proposed, and shear force calculation equations for the core zone of the new assembled concrete beam–column rigid joints and semi-rigid joints are derived.

Shaking table tests and seismic assessment of a full-scale precast concrete sandwich wall panel structure with bolt connections

A novel, light-weight, sustainable, repairable and cost-effective precast concrete sandwich wall panel structure system is proposed in this paper, including the dry bolt connections and the precast concrete sandwich panels. To evaluate the seismic performance of precast structure system, a sequence of shaking table tests is carried on the full-scale precast concrete sandwich wall panel structure, and the dynamic characteristics, damage pattern, dynamic responses and seismic fragility are investigated and analyzed by the test results under service level earthquake, design based earthquake, and maximum considered earthquake. The seismic fragility curves and failure probability curves are analyzed by the shaking table test results, which quantitatively describes the seismic performanceexpressed by probability. The results show that the precast concrete sandwich wall panel structure performs high lateral stiffness, large safety margins and high strength reserves. The precast concrete sandwich wall panel structure system presents a good seismic performance. The damage of the structure is slight under maximum considered earthquakes, and the structure has begun to enter the plastic stage. The light-weight characteristic reduces the dynamic responses, and the mild sliding between precast components consumes a fraction of seismic energy.

Seismic behavior of the assembled walls using uniform precast hollow-core concrete panels restrained by cast-in-place boundary elements in single-story buildings

To achieve efficient construction of single-story buildings and increase economic efficiency while ensuring safety, low-cost, easy-to-assemble, and good seismic performance assembled walls using uniform precast hollow-core concrete panels restrained by cast-in-place boundary elements were designed. Through the low-cyclic loading test of three specimens, the safety and reliability of the connection between the components were verified, the good seismic performance of the structure was proved, and the influence of the number (2, 3, 4) of panels contained in the specimens, that is the shear span ratio (SSR) of the specimens, on their seismic performance was investigated. The study found that all specimens finally show shear-slip damage, and with the decrease of SSR, the ultimate shear-bearing capacity of the specimen increases, the deformation capacity decreases, and the energy dissipation capacity increases. Compared with the specimen of 2 panels, the ultimate shear bearing capacity of 3 panels and 4 panels is increased by 39.2% and 88.9% respectively. The ultimate deformation capacity of 2 panels is similar to that of 3 panels, but that of 4 panels is reduced by 23.3%. In addition, these three specimens are simulated using the finite element analysis software ABAQUS. The stress nephogram of each specimen reflects the presence of vertical shear along the thin wall of the circular hole of the panels under horizontal load, and the vertical shear surface will be linked into the shear belt along the diagonal of the specimen. Combined with experiment and finite element simulation, the calculation method of the ultimate lateral bearing capacity of the structure is established. The ratio of the measured value to the calculated value is greater than 1.0, and the maximum relative error of them is only 6.85%, which proves that the calculation method is safe and reliable. The research results of this paper can provide the necessary basis for the engineering application in single-story buildings.

Seismic performance of concrete-filled steel tubular composite columns with ultra high performance concrete plates

Two 1:8 scale specimens were designed and created to examine the seismic performance of concrete-filled steel tubular (CFST) composite columns with ultra high performance concrete (UHPC) plates. Ground motion characteristics, axial pressure ratio, plate material, and mainshock-aftershock sequences were used as parameters in the pseudo-dynamic test study. The results show that the ground motion characteristics have a significant effect on the seismic response of the specimen; The initial stiffness of the specimens is mostly unaffected by the axial pressure ratio. Furthermore, the larger the axial pressure ratio, the earlier the specimen enters yielding and the more severe the final failure phenomenon; After UHPC was used in place of the plate material, the specimen's initial stiffness rose by about 13.7%, the stiffness degradation of the specimen was somewhat delayed, and the hysteretic energy dissipation increased by about 41.2%.; The specimen undergoes elastic, elastoplastic, and plastic failure stages under the aftershocks of increasing intensity. Under the mainshock-aftershock sequences of the same intensity, the seismic response of the specimens under the aftershock was not much different compared to the mainshock, and the hysteretic energy dissipation was about 67.7% and 74.5% of the mainshock respectively. These structures can withstand multiple earthquakes and have demonstrated good seismic performance.

Experimental study on seismic performance of modular steel construction beam-to-beam combined side column joint with blind bolted connection

With the increase in the construction height of modular structures, the challenge of structural seismic resistance is increasing, and the performance of joints between modules is the key to the seismic performance of modular structures. This paper proposed a modular steel construction beam-to-beam combined joint with blind bolted connection. To study its seismic performance, quasi-static tests on four full-scale T-shaped joints with different construction forms were conducted, and the failure mode, strength, stiffness, ductility, and energy dissipation of the joints were obtained. The results showed that the joint had good seismic performance, and the performance of the enhanced joint was significantly improved after blind bolts and stiffening plates were used. Furthermore, based on the test results, the simplified mechanical model of the joint was established. The calculation method of joint stiffness and bearing capacity was obtained by theoretical derivation, and the design method of the joint was proposed. The analysis showed that the calculated results were close to the experimental results, and the proposed enhanced joint could meet the requirements of rigid connection and full-strength connection joint.

Experimental Study on the Seismic Performance of New Energy Dissipation Connectors in an Autoclaved Aerated Concrete Panel with Assembled Steel Frame

This study proposes a new energy dissipation connector (NEDC) to connect an external autoclaved aerated concrete (AAC) wall panel with an assembled steel frame. To investigate the seismic performance and working mechanism of the NEDC under seismic action, horizontal low-cyclic loading tests were conducted on two sets of steel frames with different connectors using an MTS actuator. Similarly, the seismic performance and working mechanism of the AAC wall panels were elucidated using horizontal low-cyclic loading tests. Test results revealed that the NEDC increased ductility by 10.69–21.12% and energy consumption by 101.14% when compared to those obtained using hook bolt connectors. Overall, the NEDC provides good seismic performance, large deformability, and high energy consumption capacity, thereby rendering it ideal for assembled steel buildings. Furthermore, the NEDC can reduce wall panel damage during earthquake action and enhance the seismic performance of composite frames.

Effect of Hidden Column Type on Seismic Performance of the Insulated Sandwich Wall Panel Joints with Ceramsite Concrete Layer

Ceramsite concrete, with its advantages such as excellent long-term durability and thermal insulation properties, is suitable to be utilized as precast sandwich wall panels. While the lack of assessment of the seismic performance of such wall panel joints has been studied. Therefore, an experimental program was carried out to investigate and improve the seismic performance of the new type of wall panel joints. The seismic performances of the specimens were experimentally evaluated, including failure mode, loading and deformation capacity, ductility, the strain of vertically distributed steels, stiffness, and energy dissipation. The insulated sandwich wall panel joints have good seismic performance shown by the quasi-static test. The ductility coefficient of all specimens was greater than 3. The structure of the control group specimen presented a better match in stiffness, bearing capacity, ductility, and energy dissipation. The sleeve connection confirmed that the integrity of the joint, and the L-shaped hidden column could improve the ductility coefficient and equivalent viscous damping coefficient by about 4.2%. The results can promote the research of such wallboard system. This design approach of sandwich wall panel joints with lightweight concrete is broadly applicable to the exploration of more types of energy-saving wallboard systems.

Seismic behavior of a novel prefabricated thin-walled CFST double-column pier system for simple on-site assembly

To expedite the development of concrete-filled steel tubular (CFST) piers for simple on-site assembly (SOA), a novel prefabricated thin-walled CFST double-column pier system is proposed with the advantages of accelerated on-site construction, facilitated transportation, reasonable constructional cost, and good seismic performance. Two prefabricated thin-walled CFST double-column pier specimens were tested under quasi-static loading, and their failure modes, deformation characteristics, hysterical responses, energy dissipation capacity, stiffness degradation, and residual drift ratio are discussed in detail. The test results indicate that the proposed prefabricated thin-walled CFST double-column pier system shows a fairly good seismic performance with reasonable failure mode, sufficient energy dissipation, and relatively small residual deformation, and the SOA connections can effectively guarantee the overall deformation of the system under a maximum drift ratio of 4.8%. The specimen with double RC tie beams is superior in lateral resistance and initial stiffness to the one with a single RC tie beam, while they show similar performance in ductility and energy dissipation efficiency.

Seismic Response Analysis of Steel–Concrete Composite Frame Structures with URSP Connectors

The uplift-restricted and slip-permitted (URSP) connector is a new type of connector used in steel-concrete composite structures that has been proven to improve the structural performance of negative moment regions. Since this connector changes the interface restraint between the slab and steel beam, there is an imperative to study the seismic performance of steel-concrete composite frame systems with this new type of connector. In this study, the dynamic behavior of composite frame structures with URSP connectors under seismic loads was numerically investigated. First, a beam-shell mixed model was used and complex interfaces of different connectors were considered while establishing a numerical model to conduct elasto-plastic time history analysis under various seismic loads. This numerical model was validated with the frame sub-assemblage experimental results of quasi-static cyclic tests. Second, the model analysis results of structures with URSP connectors were obtained and compared with those of traditional structures. Third, dynamic response results including roof displacement, inter-story displacement, and the distribution and failure modes of plastic hinges were analyzed and compared. The comparisons indicated that the arrangement of full-span URSP connectors had a non-negligible influence on the dynamic behavior of the systems. The arrangement increased the maximum inter-story displacement by 31.5% and induced adverse effects in certain cases, which is not suggested in the application of URSP connectors. The partial arrangement of URSP connectors had little influence on the dynamic behavior of the systems, and the frame systems still showed a good seismic performance, which was the same as the traditional composite structural system. These findings may promote the application of URSP connectors in composite structures.

Research Progress on The Seismic Performance of Fabricated Concrete Structures

In recent decades, the application of prefabricated structures has become more and more extensive, especially for prefabricated concrete structures. The research on its seismic performance plays a significant role in the process of application and promotion of this structure. This paper mainly summarizes the research results on the seismic performance of prefabricated concrete structures, and it is actually based on the seismic research of dry connections, wet connections, new connections and different structural systems. The new dry connections with good seismic performance are considered to have better application prospects. In addition, it analyses the application of seismic design with recoverable functions in this field, and it is concluded that new seismic technologies such as recoverable function structures and damage control structures should be widely used. Finally, the research status of seismic performance of prefabricated concrete structures is summarized and analyzed. In the future promotion and application, it is necessary to continuously update the relevant regulations and improve seismic design methods and technologies.