Seismic Performance Index Research Articles

Seismic Behavior of Concrete Beam-Column Joints Reinforced with Steel-Jacketed Grouting

Joints in frame structures often fail before beams and columns in an earthquake and are a key part of reinforcement. In this study, to enhance the seismic performance of concrete frame structures, a steel-jacketed grouting composite reinforcement method is proposed by combining reinforcement technology, steel cladding technology, and eco-efficient materials from grouting technology. This method effectively utilizes the advantages of various materials, avoids major demolition and construction, and reduces waste and resource consumption. In order to verify the feasibility and effectiveness of the reinforcement method, one of the original joint specimens with a scale of 1:3 and one of the reinforced joint specimens were designed and tested. The experiments involved reversed cyclic testing of beam–column to measure its seismic behavior. The seismic performance indexes such as failure characteristics, hysteretic properties, and the energy dissipation capacity of the specimens were analyzed, and the corresponding finite element model was established. The influence of key parameters such as reinforcement range, steel plate thickness, and grout strength on its seismic performance was explored. The research shows that the method can effectively improve the seismic performance of the joints, and seismic performance indexes such as bearing capacity, ductility, and energy consumption of the specimens are significantly improved. The test results of the established finite element model are in good agreement. The variable parameter analysis of the finite element shows that the thickness of the steel plate has little influence on its bearing capacity. With the increase in the reinforcement range of the clad steel and the strength of the grouting material, the bearing capacity of the specimen increases. The research results can provide a reference for the reinforcement of frame structure joints.

Experimental study on seismic performance of seismic-damaged precast steel reinforced (recycled) concrete frame structure after strengthened and repaired

In order to understand the seismic performance and failure mechanism of the seismic-damaged prefabricated steel (recycled) concrete frame after strengthening and repairing, this paper uses four different strengthened methods, including carbon fiber reinforced polymer (CFRP), high-strength steel wire cloth (HSSWC), oblique support and enveloped steel jacket. Four seismic-damaged prefabricated steel (recycled) concrete frames were strengthened by single or composite strengthening, and low-cycle reciprocating failure tests were carried out on all frame specimens. The final failure mode of the reinforced specimens under simulated seismic load was observed. The seismic performance indexes such as load-displacement (P-Δ) hysteresis curve, skeleton curve, and stiffness degradation of each specimen before and after strengthening were compared and analyzed. The test results show that the strengthening methods used in this test can effectively restore the seismic performance of the seismic-damaged prefabricated steel (recycled) concrete frame. The specimens show a typical ductile failure mode, and the P-Δ hysteresis curve of the specimens is relatively full. For a single strengthened form, CFRP strengthened can more significantly restore and improve the ductility of the specimen than HSSWC strengthened, but the cumulative energy dissipation capacity of the specimen after HSSWC strengthened is stronger. The bearing capacity of the specimens after composite-strengthened is significantly improved, and the damage degree of the structure is reduced. The addition of oblique support and an enveloped steel jacket can provide greater lateral stiffness for the specimens and improve the failure mode of the specimens. The results of this paper can provide a scientific basis for the selection and design of strengthened methods for prefabricated steel-reinforced concrete structures after earthquake damage.

Cyclic behavior of cold-formed stainless steel sandwich tubular brace: An experimental investigation

Stainless steel shows promise for application in seismic-active regions. Previous research showed that stainless steel dampers could exhibit good energy dissipation capacity and high post-yield stiffness under cyclic loading. In light of that, a novel type of cold-formed stainless steel sandwich tubular brace (STB) is presented in this study, featuring one stainless steel square hollow section (SHS) tube as the load-carrying component and two additional stainless steel SHS tubes providing a buckling-restraining effect. Six specimens were tested under cyclic loading, varying parameters including the cross-section slenderness of the core tube, restraining ratio and loading histories. Loading protocols encompassed standardized ones following the Chinese specification (CN) and American provision (US), as well as a protocol representing the near-fault earthquakes (NF). Failure modes, hysteretic response and seismic performance indexes were obtained. Results showed that the hysteretic curves could maintain stable. Under the CN loading protocol, the specimen with a slender core cross-section exhibited uniform local buckling. The strain hardening coefficient ω stayed within the range of 1.46–1.58. The specimens exhibited a slow decay rate of tangent stiffness, highlighting their relatively high post-yield stiffness. The cumulative energy dissipation factor could reach 658, signifying good energy dissipation capacity. Additionally, under NF loading, specimens exhibited enhanced cumulative ductility compared to CN or US loading. Furthermore, an evaluation was conducted to assess the suitability of existing design methods for preventing overall buckling and local bulging in stainless steel STBs. It indicated that the current design approaches tended to be overly conservative for both overall and local stability design of stainless steel STBs, primarily due to the lack of consideration for SHS core stiffness and the interactions between flanges and webs, respectively.

Seismic performance of an innovative self-centering and repairable connection with SMA bolts in modular steel construction

Modular steel construction (MSC) is widely noticed and adopted in the building industry for its benefits of short construction period, low carbon emission, and great flexibility. The performance of inter-module connections, including the strength, toughness and ductility, is the focus of maintaining the load transfer mechanism and overall stability of modular structures. The structure with favorably designed connections can dissipate expected energy under cyclic loading with reduced structural damage. A self-centering and repairable connection (SRC) is herein proposed, with the benefits of a distinct load transmission path and easy assembly. Four full-size specimens were fabricated and tested under low-cycle loading, and the tested specimens were subsequently repaired by replacing angle cleats. The failure mode and bearing capacity of both SRC and repaired SRC specimens were investigated. Several seismic performance indices of the specimens, including hysteresis curves, strength and stiffness degradation, energy dissipation capacity, self-centering and repairable ability, were obtained. Furthermore, the performance of the SRC was comprehensively assessed according to Eurocode 3 Part 1–8, Chinese code GB 50011-2010, and American code AISC 341-16. In addition, an accurate finite element model (FEM) of the SRC was created and verified using experimental results. The developed FEM was used to investigate the effects of critical parameters, including angle cleat thickness and grade, vertical bolt diameter, and SMA bolt number and diameter, on the seismic performance of SRCs. Both experimental and FEM results show that only the replaceable angle cleats experienced the noticed plastic deformation for SRC specimens under cyclic loading, and SMA bolts provided the required self-centering force. It can be hence concluded that the proposed SRC can achieve the expected self-centering and recovery function.

Seismic performance of conrete‐filled steel tube column‐reinforced concrete beam frame using 100% recycled coarse aggregate

AbstractThis paper presents an experimental study of recycled concrete‐filled steel tube (CFST) columns with reinforced concrete (RC) beam frames using recycled aggregate under cyclic loading. A 1/3‐scale model of a CFST column‐RC beam frame with 100% recycled coarse aggregate was tested, the failure process and mode were monitored, and the hysteresis and skeleton curves were obtained. The seismic performance indexes were analyzed based on the test data, including the seismic force, plastic hinge sequence, ductility coefficient, inter‐story drift, dissipation capacity, and stiffness degeneration. The general behavior of the CFST column‐RC beam frame is discussed and compared with that of a normal aggregate concrete‐RC frame structure. The test results demonstrate that CFST column‐RC beam frames with 100% recycled coarse aggregate exhibit remarkable seismic performance and can be applied and popularized for construction in aseismic regions.

Seismic performance evaluation of precast post-tensioned high-performance concrete frame beam-column joint under cyclic loading

Precast concrete structures have developed rapidly because they meet the requirements of green and low-carbon social development. In this paper, a precast post-tensioned high-performance concrete frame beam-column joint was proposed, and the low-cycle reversed load test was performed on the four proposed joints. The main differences between the four joints are the different prestress values applied by the joints and whether the beam-column joint is provided with L-shaped steel. The seismic performance indexes such as hysteresis curve, stiffness degradation, deformation capacity, energy dissipation capacity and residual deformation of each node were obtained through experiments. By comparing various seismic performance indicators, it could be found that the use of high-performance concrete could effectively avoid the phenomenon of local crushing of concrete due to excessive prestressing. At the same time, it was found that the setting of L-shaped steel plate at the beam-column junction could effectively avoid the early damage at the beam-column junction. On the basis of the test, the three-line restoring force model of the joint was established by the method of experimental regression analysis. The model could better reflect the stress situation of each stage of the joint. Based on the experimental and theoretical analysis, the finite element analysis model of the joint was established, and the model calculation results were in good agreement with the experimental results.

Numerical Simulation Study on the Seismic Performance of Prefabricated Fiber-Reinforced Concrete Beam–Column Joints With Grouted Sleeve Connections

Based on the available experimental data, fiber models for four prefabricated fiber-reinforced concrete beam–column joint specimens with grouted sleeve connections are first developed in OpenSees software. Then, the simulated seismic performance of the specimens is compared with the experimental results. Finally, the effects of axial load ratio and shear-to-span ratio on the seismic performance of the specimens are further investigated numerically. The results indicate that Concrete02 material model and Reinforcing Steel material model can accurately simulate the constitutive relationship of concrete and reinforcing steel, respectively; the beam–column joint elements can accurately simulate different damage behaviors of the joint zone. Fiber-reinforced concrete can significantly improve the seismic performance of the specimens. The relative errors of the simulated seismic performance indexes are about 15%. It is recommended that the optimum value of shear-to-span ratio for prefabricated FRC BCJs is 2.0–2.5. The effect of axial load ratio on the seismic behavior of PBCJs-CM is very small, and can be negligible in the case that the prefabricated FRC BCJs has a moderate value of shear-to-span ratio. The fiber model developed in this article can provide a numerical simulation basis for subsequent studies of prefabricated fiber-reinforced concrete beam–column joint specimens with grouted sleeve connections.

Effect of nano-SiO2 modification on the seismic performance of recycled aggregate concrete shear walls

Nano-silicon dioxide (nano-SiO2) can strengthen recycled aggregates and interface transition zones (ITZs), thereby improving the properties of recycled concrete structures. This study adopted nano-SiO2 modifications to improve the seismic behavior of recycled concrete shear walls. Quasi-static tests of one natural aggregate concrete shear wall and four concrete shear walls with different replacement ratios (30%, 50%, 70%, and 100%) of nano-SiO2 modified recycled aggregate (NSMRA) were conducted. The ductility factor, energy dissipation, lateral displacement components, stiffness, and strength degradation of NSMRA concrete (NSMRAC) shear walls were evaluated. The replacement ratio effects of NSMRA on the seismic behavior of shear walls were analyzed. It was determined that the NSMRAC shear walls exhibited higher ductility factor compared to recycled aggregate concrete (RAC) shear walls with similar conditions. The seismic behavior of the shear walls degraded as the replacement ratio of NSMRA increased. Based on the comprehensive evaluation of failure patterns and seismic performance indexes, the replacement ratio of NSMRA is suggested to be taken as 50% in the concrete shear walls. Finally, based on the summary of experiments and studies on the seismic behavior of RAC shear walls with shear failure, the applicability of existing formulae was evaluated by calculating the shear capacity of RAC shear walls, and the effect of nano-SiO2 modifications on the shear capacity of recycled concrete shear walls was analyzed.

Cold–formed thin–walled steel walls filled with phosphogypsum subjected to lateral cyclic loading: testing and analysis

In order to improve the shear capacity and seismic performance of cold–formed thin–walled steel (CFS) walls, in this research, a novel CFS wall filled with phosphogypsum (PG) was developed. Taking PG filling area and covering the wall with sheathing as design parameters, four full–scale test specimens were designed and constructed. Failure mode and seismic performance indexes of each specimen were investigated by performing cyclic loading tests and the effect of PG filler on CFS wall seismic performance was evaluated. Research results showed that PG filler significantly improved the seismic performance and shear capacity of CFS walls. Importantly, the proposed wall presented a remarkable dual–mechanism of lateral force resistance, which was provided by PG filler and wall sheathings, respectively. In addition, analytical models were developed for the calculation of the shear capacity and lateral stiffness of the proposed walls, which presented high prediction accuracy.

Study on the oblique seismic behavior of reinforced concrete L-shaped columns strengthened with carbon fiber reinforced polymer slabs

The oblique seismic performance of reinforced concrete L-shaped columns is an important factor that affecting the safety of structures. However, there is limited research on the oblique seismic performance of reinforced concrete L-shaped columns strengthened with carbon fiber reinforced polymer (CFRP) slabs mounted at the column bottom. In order to address the theoretical gap and meet the practical requirements, finite element analyses were conducted on L-shaped reinforced concrete columns. These analyses considered various parameters, including loading angle, strengthened method, volume stirrup ratio and axial compression ratio. The seismic performance indexes of L-shaped columns such as failure state, hysteretic curve, skeleton curve, carrying capacity, and ductility are investigated. The analyses results show that the failure mode of L-shaped column is bending failure, and the seismic performance of strengthened L-shaped column is better than that of unstrengthened L-shaped column. The CFRP slabs mounted at the column bottom could increase the peak carrying capacity and decrease the ductility coefficient of specimen. Therefore it is suggested to employ the method of strengthening column bottom by CFRP slabs in practical engineering application. Moreover, the peak carrying capacity of specimens under different loading angles is similar. With a higher loading angle, the positive peak carrying capacity of specimen increases, while the negative peak carrying capacity decreases. Finally, this study presents a novel method for determining the compression-bending carrying capacity of reinforced concrete L-shaped column, where the influence of torsion action is taken into account. This method offers valuable insights for the engineering design.

Research on Nonlinear Behavior of Local High-Performance Concrete Beam-Column Connections.

The seismic performance index of prefabricated structures is generally obtained via experimental analysis. However, in experimental research, it is impossible that every influencing factor can be taken into account. Therefore, the finite element analysis method can be used as a supplementary method for experimental research to carry out parametric analysis of joints. Based on this test, a hysteretic model of steel bars is developed on the ABAQUS platform; meanwhile, the model is used to simulate the seismic analysis of the proposed local reinforced joints. The hysteresis curve obtained via simulation exhibits a high degree of coincidence with the experimental results. Based on the validated model, a detailed parameter analysis of prefabricated local reinforced concrete frame joints is carried out. The analysis results illustrate that the axial pressure ratio at the top of the column has a minimal impact on the joint's performance. Decreasing the stirrup ratio within the core region, enlarging the diameter of the PC steel bar, and increasing the concrete strength that is poured in the keyway and the core region can raise the cumulative energy consumption of the joints, thereby reducing the damage degree of other units and improving the maximum bearing capability of the joints.

Seismic Behavior of Demountable Reinforced Concrete (RC) Beam-to-Column Joints with Damage-Control Fuses

In this paper, a new type of assembled RC beam–column joint with a beam-end steel cover-plate connection is proposed to achieve seismic toughness and damage control of the joint. Energy-dissipation plates with different structural forms are proposed, and a series of seismic performance indexes of the joints are calculated and analyzed by using the finite element method. The energy-dissipation plate with an arc notch can reach the yield condition faster, and the ultimate bearing capacity of the joint reaches the maximum. The bending design of energy-dissipation plates is carried out by calculating the demand bending moment, and energy-dissipation plates of different structural forms are simulated and verified. The results show that the proposed design formula can ensure that the bending moment at the beam end still maintains elastic deformation when the energy-dissipation plate yields. The important parameters affecting the bending moment of the weakened part in the middle of the energy-dissipation plate are analyzed. Finally, this paper also analyzes the important parameters affecting the seismic performance of the joints. The results show that the seismic performance of the newly assembled RC beam–column joints proposed in this paper is better than that of cast-in-place joints. Increasing the longitudinal reinforcement ratio appropriately can greatly improve the ultimate bearing capacity and ductility of the joints. Increasing the thickness of the energy-dissipation plate, increasing the strength of the energy-dissipation plate, increasing the axial compression ratio of the column, increasing the strength of the concrete, and increasing the strength of the shear web can improve the ultimate bearing capacity of the joints but also reduce their ductility. Under different axial compression ratios, the strain in the core area of the joints is low, and the compressive damage of the concrete is zero, which verifies the effectiveness of the damage-control design of the proposed model.

An Experimental Study on Flexural-Shear Behavior of Composite Beams in Precast Frame Structures with Post-Cast Epoxy Resin Concrete

Epoxy resin concrete has superior mechanical properties compared to ordinary concrete, and will play an increasingly important role in urban construction. In this paper, the application effect and prospect of epoxy resin concrete in precast composite frame structures are discussed. Taking the joint surface of the old and new concrete at the end of the composite beam as the research object, three specimens were devised and fabricated. Subsequently, a horizontal cyclic load test was conducted, and the seismic performance indices were analyzed. Multiple finite element models were established to assess the influence of precast concrete strength, the diameter of the longitudinal bar of the beam, the shear span ratio, and the epoxy resin concrete post-cast area, among other factors, on the seismic performance of the beam end. Four findings indicate the following: Firstly, epoxy resin concrete, characterized by its high performance attributes, can be used as a post-cast material in precast concrete structures. Secondly, when the strength of the post-cast epoxy concrete approximates or slightly exceeds that of the precast concrete, and the ratio of longitudinal reinforcement and shear span ratio are appropriately balanced, the operational performance of the composite beam frame structure is enhanced. In addition, when post-cast epoxy resin concrete is employed in the beam-column joint area, the mechanical performance of the composite beam end in the joint area matches or even surpasses that of the structure that was cast in situ. And subsequently, the expansion of post-cast area resulted in better mechanical performance. Finally, when the area of post-cast epoxy resin concrete is a non-node area, the mechanical properties of the composite beam end are worse than the former. However, the amount of epoxy resin concrete used will be greatly reduced, and as the precast node area expands, the bearing capacity of the beam end will increase and gradually approach the cast-in situ structure, indicating that this construction scheme also has advantages.

Seismic performance of special-shaped hexagonal concrete filled steel tubes with inner diaphragm plates and shear studs

With the development of the high-rise buildings, the columns with special cross-sectional shapes are frequently adopted for architectural and aesthetic purposes. The concrete filled steel tube (CFST) is a reasonable choice for such requirement due to the characteristics of excellent seismic performances, construction efficiency and strong adaptability to special shapes. This paper focuses on the seismic performance of a special-shaped hexagonal CFST column with an inner diaphragm plate and shear studs adopted in a super high-rise building. Experiments were conducted on five column specimens under axial compressive force and lateral cyclic loading to investigate the influence of various parameters including loading angle, axial compression ratio, shear studs and the type of in-filled concrete. In one of the specimens, the ultra-high performance concrete (UHPC) was used as the in-filled concrete to substitute the conventional normal strength concrete, and the effects on the capacity and ductility of the column were revealed. Then the failure mode, the load-deflection curves, seismic performance indexes and the strain distribution were analyzed. The flexural capacities of the columns were evaluated by the fiber section model, where the failure criterion considering the buckling of steel tube was proposed and the effects of studs were included. Finally, the contribution to axial force and bending moment from outer steel tubes, inner diaphragm plate and in-filled concrete were calculated and compared based on the proposed model. It is found that the fiber section model considering the steel plate buckling and strengthening effects of studs precisely predicted the moment-curvature curves and the flexural capacity of the test specimens. The contribution of the inner diaphragm plate was considerable which could not be neglected.

Seismic performance of cold-formed thin-walled C-shaped steel composite wall with fireproof straw boards cladding

ABSTRACT In order to study the seismic performance of cold-formed, thin-walled C-shaped steel composite wall, a set of cold-formed thin-walled C-shaped steel skeleton structure and a set of composite wall covered with fireproof straw boards on both sides were tested with a low cyclic alternative load. The seismic performance indexes, such as bearing capacity characteristic value, lateral stiffness, ductility coefficient, energy dissipation coefficient and stiffness degradation, were analysed by obtaining the backbone curves of each group of specimens. The effects of fireproof straw boards on the seismic performance of the composite wall were compared, and a mechanical analysis model of the cold-formed thin-walled C-shaped steel composite wall was established by using ANSYS/structural finite element software. The results show that the damage patterns, backbone curves and capacity characteristic values of the finite element model are in general agreement with the tests. The bearing capacity and lateral stiffness of the light steel skeleton structure without boards is very low, while the bearing capacity of the composite wall with straw boards on both sides is significantly increased. The lateral stiffness increased by 10.76%, the ductility coefficient increased by 27.34% and the energy dissipation coefficient decreased by 45.8%.

Seismic behavior of precast prestressed concrete frame joints with different energy dissipation designs

The unbonded post-tensioned precast concrete joint based on PRESSS (Precast Seismic Structural System) technology has a simple form, convenient construction, and strong deformation-recovery properties. In this paper, both experimental and theoretical analysis methods were used to study the influence of different energy dissipation components on the seismic performance of the unbonded post-tensioned precast concrete joint. First, based on the existing ‘plug-and-play’ energy dissipation device, this paper improved its construction and designed two types of joints with new external energy dissipaters and internal energy-dissipating bars, respectively. Subsequently, low-reversed cyclic loading experiments were conducted. The two joints’ seismic performance indexes, failure mode, hysteresis curve, skeleton curve, ductility coefficient, and residual deformation were compared and analyzed. The experimental results showed that internal energy-dissipating bars exhibited greater energy dissipation. In contrast, the joint with the new external energy dissipater had higher initial stiffness than the joint with internal energy-dissipating bars. In addition, the force transmission mechanism and the calculation formula of the initial rotational stiffness of the joints were deduced through theoretical analysis, and the theoretical derivation was further verified by combining the experimental values. Overall, both joints conformed to the definition of semi-rigid connections in EC3, and the joint design conformed to the “strong column and weak beam, strong joint and weak member” principle. Finally, a new anchoring system for the energy dissipaters is proposed to ensure the effective connection between the energy dissipater and the bearing.

Seismic Performance and Calculation Method of Precast Reduced Beam Section Connection

To prevent brittle damage and improve the post-earthquake rapid repair capability of beam–column connections, a precast reduced beam section (PRBS) connection joint that can be rapidly repaired under earthquake action was proposed in this study. Four specimens, including a repaired specimen, were subjected to a quasi-static test to investigate the seismic performance and repair ability of the connection. Seismic performance indices such as the failure mode, hysteresis curve, skeleton curve, strain distribution, and ductility were obtained through observations and analyses. The results indicated that the novel connection exhibited superior load-bearing, energy dissipation, and rotation capacities, compared to the welded flange-bolted web and traditional bone-weakened connections. This novel connection effectively relocated the plastic hinge to alter the failure mode and prevent brittle damage. Additionally, rapid post-earthquake repair was achieved by replacing the dog-bone-style splice section, maintaining a high load-bearing capacity and seismic performance. Finite element (FE) models were established to analyze the mechanical behavior of the specimens, and a parametric analysis was conducted to study the influence of different parameters on the load-bearing capacity of the connection. Based on the experimental and FE analysis results, the possible yield and failure modes of the connection were analyzed, and a calculation method for the bearing capacity of the PRBS connection was proposed. A comparative result demonstrates that the proposed calculation method can accurately predict the load-carrying capacity of a connection.

Numerical simulation methods for reinforced concrete columns considering parameter stochasticity

Reinforced concrete column specimens with the same parameters often show differences in bearing capacity and deformation under the same loading path. Most of the existing studies attribute the causes to recording instrumentation errors or randomness in material and bond dimensions, but the method to improve the accuracy of numerical simulation of the reinforced concrete components is still unclear. For a given member, the randomness of material and geometry is an important cause of simulation error, which should be taken into account to improve the simulation accuracy. A weighted least squares estimation (WLS) method is used to fuse the test samples of reinforced concrete member section sizes, reinforcement and concrete with confidence factors as weights. The probability distribution functions of reinforced concrete member section sizes, reinforcement and concrete are calculated by a genetic algorithm method. Based on the existing seismic performance test data of reinforced concrete columns, a stochastic finite element model of reinforced concrete columns is developed for seismic performance analysis using Monte Carlo method through a mixture of two software programs, MATLAB and OpenSees. The numerical seismic performance indexes of eight types of reinforced concrete columns were compared with the test results to verify the importance of introducing stochastic parameters into the model. The results demonstrate the simulation accuracy of the finite element model considering parameter randomness is 88% higher than that of the finite element model without considering parameter randomness, which proves the effectiveness of the numerical simulation method for reinforced concrete columns considering parameter randomness.

Hysteretic and rotational performance study of outwardly extending shape-steelprefabricated beam-column joints

This paper proposes fully-bolted extending shape steel prefabricated beam-column joints to achieve rapid construction and reliable connection of the precast reinforced concrete frame. The prefabricated component uses steel tube-concrete composite structures with outwardly extended shape steel, which achieves efficient installation and internal force transfer. Horizontal hysteresis tests were conducted on four components to determine the joint mode of failure and seismic performance index. The results show that the joint exhibits a “double plastic” failure mode, with plastic deformation occurring at the end of the reinforced concrete beam and buckling deformation at the shaped steel. Compared to cast-in-place joints, the new joints have a 30% increase in yield load, a 51% increase in peak load, an approximately 50% increase in initial stiffness, a 33% increase in equivalent viscous damping coefficient, and a ductility coefficient greater than 4.0. Analysis of strain showed that the stiffness of the connection area was too high, which will have a significant extrusion effect on the concrete at the end. Reducing the thickness of the steel plate in the joint space and weakening the shape stee by opening holes can significantly improve the rotational deformation capacity of the joint - further developing the plastic zone of reinforced concrete beams to improve the mechanical performance of the joint. Finally, the finite element model of the joint is established, and the numerical calculation is in good agreement with the experimental results. The research in this paper can provide technical support for the engineering application of the prefabricated joint.

Quantification of seismic performance index limits and evaluation of seismic fragility for a new rectangular prefabricated subway station structure

To promote the acceptance of prefabricated technology in underground engineering, the numerical seismic fragility analysis of a prefabricated underground structures was scrutinized. A method to quantify the limit values of the seismic performance index of rectangular prefabricated subway station structure was proposed. In addition, seismic fragility curves of the two-story three-span prefabricated subway station structure were constructed based on peak ground velocity (PGV) and peak ground acceleration (PGA), which can be used as an effective tool to quickly evaluate the seismic performance of this type of prefabricated underground structure, and compared with the cast-in-place subway station structure. The results demonstrate that the ground motion and site class have an intertwined influence on the dynamic response of the underground structures. That is, as the site equivalent shear wave velocity decreases, the ground motion characteristics have a greater influence on the underground structure dynamic response and its susceptibility to damage. For shallow buried multi-layer underground prefabricated structures, the PGV is the best seismic intensity measure (IM) for all site classes. The prefabricated subway station structure is found to be less vulnerable to damage than the cast-in-place subway station structure.