With the advantages of standardization， integration and industrialization， modular steel building has quickly attracted the attention of academia and industry. In this paper， the authors summarize the semi-rigid and rigid connection of modular steel buildings and mainly focus on weak connection， poor cooperative performance of adjacent components and weak robustness. The advantages and disadvantages of existing modular connections are elaborated from mechanical mechanism and construction. The idea of "connected at both beam and column end" is proposed. For the cooperative performance of beam-beam and column-column between modules， the similarities and differences with steel-concrete composite beams and lattice columns are analyzed. Considering the decoration and construction， the solution of composite beam （column） with discontinuous connection is put forward. Additionally， the patterns influencing the robustness of modular steel buildings are summarized. Based on the existing research， it is recommended to conduct more in-depth research on rigid connections between modules， composite components with discontinuous connection， and system analysis.

Compared with block precast bridge deck， transverse full-width prestressed precast bridge deck has better integrity， faster construction， and a better application prospect in assembled composite beam bridge. The wet joint connection of the precast bridge deck under negative bending moment is the key part of the composite beam. Therefore， the mechanical properties of full-width prestressed precast bridge deck composite beam under negative bending moment are studied， the influence of the number of transverse prestressed bars， the arrangement of prestressed bars， the degree of shear connection and the materials at the joints on the mechanical properties such as structural failure mode， cracking load， bending bearing capacity and load-displacement curve is made clear， and the stress distribution at the joints of precast slabs is revealed. An improved effective moment of inertia superposition method for deflection calculation of precast bridge deck composite beams with complete shear connection is proposed， which considers the influence of longitudinal and transverse prestress and is in good agreement with the numerical results. For composite beams with partial shear connection， the domestic and foreign codes are compared， and it is concluded that the Standard for Design of Steel Structures in China is more applicable.

In order to investigate the axial compression bearing capacity of 7075-T6 aluminum alloy square tubes， nine specimens were fabricated and subjected to axial compression tests. The study obtained the ultimate bearing capacity， failure modes， and load-axial displacement curves of the specimens. Finite element models of the specimens were established for numerical analysis， and the effectiveness of finite element numerical analysis was validated by comparison with experimental data. Parametric analysis was conducted using finite element numerical analysis， proposing a overall stability coefficient-relative slenderness ratio curve suitable for 7075-T6 aluminum alloy square tubes. The paper discussed the influence of local buckling on bearing capacity as the relative slenderness ratio varied. The results indicate that 7075-T6 aluminum alloy square tubes exhibit certain ductility. The established finite element models accurately simulate the entire loading process and ultimate bearing capacity of the specimens. The proposed overall stability coefficient-relative slenderness ratio curve has better accuracy than the softening curve. For members with the same cross-section but different relative slenderness ratios， the influence of local initial geometric defect on the ultimate bearing capacity varies.

Autoclaved Lightweight Concrete （ALC） walls have become a commonly used wall form in prefabricated building structures， but wall cracking， which often occurs during normal use， adversely affects the aesthetics and durability of the building. In order to study the cracking resistance of embedded ALC wall panels and their effect on the stress performance of steel frames， this paper designs and completes the quasi-static full-scale tests of two single-story single-span rigidly-jointed steel frame specimens with embedded ALC walls which are connected to the steel frames with in-built anchors and pipe clips， respectively. Varying different wall finishes， the hysteresis curves， skeleton curves， stiffness degradation curves of the specimens are obtained from the actual measurements and the key experimental phenomena are observed. The test results show that the hysteretic curves of the two specimens are full hysteresis loops， the bearing capacity of the built-in anchor specimen is slightly higher than that of the pipe clip specimen， and the specimens have a good ability to work together. Considering the load capacity and stiffness， the lateral resistance of the built-in anchor specimen is better than that of the pipe clip specimen. The use of modified two-component MS adhesive as the connection material between ALC wall panels and steel frames results in later cracking compared to the use of polyurethane foam connection， which indicates that MS adhesive has a good deformation capacity， which helps to improve the cracking resistance of the wall.

Based on the lightweight steel-concrete framework system of modular wall structures， this study proposed a lightweight steel-concrete composite column-H-shaped steel beam joint suitable for this system. In order to study the mechanical properties of this joint， monotonic loading tests were carried out on three groups of beam-column joint specimens. The experimental results indicate that under monotonic loading at the beam end， the joint exhibits distinct semi-rigidity characteristics. The failure is characterized by yielding deformation of the flange of the combined steel column and concrete cracking， ultimately leading to joint failure due to excessive bending deformation of the top angle steel and the cracking of the stiffener weld. A refined simulation was conducted using ABAQUS finite element software. The deformation process and failure characteristics of the finite element model agree with the experimental results. The researchers consider three key parameters， namely， the height of the H-shaped steel beam section， the thickness of the C-shaped steel， and the thickness of the angle steel， a parametric analysis was performed. The results indicate that increasing the beam section height and the thickness of the angle steel connector significantly enhances the joint's flexural load-carrying capacity and initial rotational stiffness. In contrast， increasing the thickness of the C-shaped steel has a limited impact on the joint's flexural load-carrying capacity， with a minor effect on the initial rotational stiffness.

To provide experimental data and recommendations for the application of high-strength steels in low-temperature environments， this paper focuses on two key influencing factors： welding heat input and different delivery conditions of base metals. Two types of high-strength steels， Q550D and Q690D with thicknesses of 20mm， were selected in thermo-mechanically controlled process （TMCP） and quenched and tempered （QT） conditions. Three commonly used gas shielded welding heat inputs of 1.0 kJ·mm^-1， 1.5 kJ·mm^-1， and 1.9 kJ·mm^-1 were applied to prepare the joints. The impact toughness tests were conducted， and the results were analyzed and compared. A systematic study was performed on the Charpy impact energy and transition temperature of the base metal， weld metal， and heat-affected zone （HAZ） in butt joints under different delivery conditions. The results indicate that the effect of welding heat input on the impact toughness of various regions of the joints is insignificant， while the delivery condition significantly affects the impact toughness. Specifically， the impact toughness of the HAZ in QT steel joints is superior to that of the base metal and weld metal， whereas in TMCP steel joints， the impact toughness of the HAZ is lower than that of the base metal and weld metal. The study on the ductile-to-brittle transition temperature under controlled conditions suggests that the high-strength steels used in this study exhibit good low-temperature sensitivity.

The novel T-head one-side bolt can effectively solve the problem that the traditional high-strength bolt cannot be directly applied to the bolted beam to tubular column joints. However， the bearing mechanism of each component in the beam-column joint with this novel bolt is still unclear and needs to be further explored. The T-head one-side bolt is characterized by the shape of the bolt hole on the endplate and tubular column. To explore the mechanical response and bearing mechanism of the endplate and beam components in this novel bolted connection， the finite element analysis software ABAQUS was used to carry out a systematic numerical analysis on the tensile performance of the T-stub connections based on the component method. The main research contents and conclusions are as follows： an accurate three-dimensional finite element model of the connection was established， and five yield line patterns on the T-stub flange in T-head one-side bolted joint was studied. Finally， the calculation formula for the yield strength of T-stub joints with T-head one-side bolts is given based on the principle of virtual work and the yield line theory.

In order to study the behavior of cold-formed thin-walled stainless steel built-up box section stub columns， a total of 25 fixed-ended stub columns including 14 built-up section specimens without holes， 6 unstiffened channel or edge-stiffened channel section specimens and 5 built-up section specimens with circular web holes were tested under axial compression. The material of specimens was S30408 austenitic stainless steel. The experimental results involving failure modes， ultimate capacities and responses of load versus axial shortening were obtained and fully documented. The experimental results show that the type of built-up section has a significant effect on the ultimate bearing capacity of the built-up section column， in which the test specimens of CC-section and UU-section exhibit the largest and smallest bearing capacity respectively. The ultimate bearing capacity of built-up UU-section specimens is larger than the sum of the bearing capacity of the single channel section specimens. The holes on the web have almost no weakening effect on the ultimate bearing capacity of the specimens when the hole diameter-to-web height ratio is less than 0.5. The test results were compared with predictions calculated by the design method as per the current American Specification ASCE/SEI 8-22. It is found that the test strengths were lower than the predicted values， indicating that the current codified provision in ASCE/SEI 8-22 is not applicable to be directly used for ultimate bearing capacity predictions of the cold-formed thin-walled stainless steel built-up box section stub columns.

Steel frame with the reactor is subjected to large and high-frequency dynamic load when the reactor is stirring. However， the design of this kind of steel frame structure usually adopts the static design method， and the static analysis cannot accurately describe the dynamic effect of the reactor acting on the structure. In order to efficiently research the dynamic effect of the steel frame supporting the reactor during the operation of reactor， a simplified modeling method is proposed in this paper to connect the reactor dynamic system with the steel frame using mass points and beam elements. Based on the current standard Vessel Supports—Part 4： Supporting Supports （NB/T 47065.4—2018）， the performance of the bottom joint of the reactor support， the overall structure， and the dynamic response of the reactor stirring blade under different rotation directions are studied， and the optimization design research on this type of structure is conducted. The results show that the vessel supports and joints designed according to the current standard are the weak parts of the structure， while the optimization design of the support based on the S-N fatigue curve of steel can ensure the structure remain within the elastic limit during normal operation. The method of "opposite of adjacent" used on setting the rotation direction of the reactor stirring can make the load-bearing structure have the minimum elastic deformation. This study provides some reference for the related design and research work.

The application of ultra-high performance concrete （UHPC） to steel reinforced concrete structures can improve the load carrying capacity， reduce the cross-section size， and solve the problems of complex construction caused by the intensive configuration of stirrups and shear members. The current finite element simulation study of steel reinforced UHPC beams is mainly a parametric qualitative study of bending capacity， ignoring the bond-slip effect between steel and UHPC， which lacks the assessment of its interfacial bond performance and combination effect， as well as the in-depth discussion of the stress performance of the UHPC in tensile zone. In this paper， the finite element simulation analysis of the bending performance of steel reinforced UHPC beams was carried out based on ABAQUS， and the strength of UHPC， the strength of steel， the longitudinal reinforcement ratio and the steel ratio were parametrically investigated. The load-mid-span deflection curves， cross-section strain distribution， interface bond stress distribution， and tensile zone performance of the UHPC were analyzed. The main conclusions are as follows： （1） The loading process of the composite beam can be divided into four stages： the fully elastic stage， the damaged working stage， the plastic hardening stage， and the ductility development stage. （2） The UHPC in the tensile zone can still participate in the section bending resistance at the peak load， and suggestions for the value of the equivalent stress reduction factor for the tensile zone of UHPC are proposed based on parametric research. （3） The bond stress of the upper flange is mainly concentrated at the loading area， while the distribution of the bond stress on the lower flange is controlled by the development of cracks. The bond performance between the steel section and UHPC at the interface should be improved in the design by means of shear connectors or surface treatment of the steel profiles. （4） During the design process of composite beams， the strength and configuration rate of the steel profiles should be limited to ensure that the composite beams have good ductility and the UHPC in tensile zone exhibits good load-bearing performance.

In order to accurately evaluate the seismic damage of concrete-filled steel tubular （CFST） arch bridge， this paper regards the arch bridge system as a series-parallel system， that is， the key systems of the arch bridge system are connected in series， and the single components of different key systems are connected in series or in parallel. Taking a CFST arch bridge as the research object， the seismic response values of each component of the arch bridge are obtained by time-history analysis and neural network prediction. Based on the Copula function， the vulnerability of each key system and the overall system of the arch bridge are obtained respectively， and compared with the system vulnerability based on the first-order boundary method. The results show that the accurate seismic response value of arch bridge structure can be obtained by neural network prediction. When the peak ground acceleration A _PG=0.4g， the prediction accuracy rate exceeds 90%， and with the increase of A _PG， the accuracy rate gradually increases. Among the key component systems of the arch bridge， the failure probability of the arch column system is the highest， and the seismic isolation measures should be taken in the seismic design. The failure probability of the wind bracing system is the lowest， and the influence of the wind bracing system can be ignored in the vulnerability analysis of the arch bridge system. The vulnerability of the arch bridge system based on the series-parallel system is between the upper and lower bounds of the first-order boundary method. When the A _PG=0.3g， the failure probabilities of the series-parallel system under mild， moderate and severe damage conditions are 98%， 94% and 25%， respectively. The relative deviations from the upper bounds of the first-order boundary method are -1.4%， -3.1% and -16%， respectively， and the relative deviations from the lower bounds are 0.6%， 3% and 11%， respectively. It is obviously more reasonable to use the series-parallel system to analyze the vulnerability of the CFST arch bridge.

The large-span steel roof structure adopts a segmented and stepwise overall lifting construction technique. During the construction process， there are sudden changes in the structural system and boundary conditions， and the overall lifting is a dynamic process with abrupt variations in the structural force state. In response to the dynamic construction process， including the overall lifting， stress and deformation change rate indicators are proposed based on first-order differences of time series. A three-level early warning mechanism and thresholds for stress and deformation are introduced based on simulation results of the construction process and the 3σ criterion. A monitoring of component stress and structural deformation was conducted during a static loading test on a K6 reticulated shell， with the monitoring results analyzed and used for early warning. The results indicate that before the overall collapse of the shell structure， there are clear nonlinear characteristics in the structural force state. The proposed stress and deformation change rate indicators， along with the early warning mechanism， can effectively warn of nonlinear changes in the force state before an overall collapse， allowing personnel to take emergencymeasures in advance. The proposed change rate monitoring indicators and early warning mechanism were applied to the overall lifting process of the steel roof structure at Shanghai Songjiang South Station to verify the feasibility and effectiveness of the proposed method. The results show that the change rate indicators and their early warning mechanism can effectively warn of abrupt changes in the structural force state caused by load and boundary changes during the lifting process， validating the effectiveness of the proposed method.

As an independent energy-dissipating component designed separately from the eccentrically braced steel frame， the replaceable shear links not only confine the plastic deformation of the structure to the region of the energy-dissipating links during large earthquakes， but also， more importantly， facilitate the repair of the structure after the earthquake. In this paper， three scaled models of this steel frame structure were fabricated and unidirectional shaking table tests were conducted to obtain the dynamic characteristics， plastic development and damage mechanism of the structure， and the stress distribution， displacement response and acceleration response of the model were analysed and studied. The results show that the specimen has good energy dissipation performance， and the sequential energy dissipation of shear links and buckling-restrained brace members makes the structure have good seismic performance under earthquake. The maximum inter-story drift angle of the buckling-restrained eccentrically braced steel frame specimen with replaceable shear links meets the requirements of the code， and it has a good safety as well as strength reserve. The structural deformation is mainly dominated by shear deformation， and the increase of shear force in each layer is relatively balanced， and it has excellent seismic performance. The acceleration amplification factor of the multi-story structure can be reduced under large earthquakes to effectively reduce the dynamic response of the structure.

To promote construction industrialization and improve the seismic performance of moment resisting frames with concentrically brace， a new type of partially encased composite （PEC） brace is proposed. Low-cyclic reversed loading tests were carried out on three PEC braces and one steel brace. Failure modes， hysteretic curves， initial stiffness， bearing capacity， ductility and energy dissipation capacity were studied. The results show that the PEC frame and the PEC brace cooperate well as the two structural seismic lines. And compared to the steel brace， three PEC braces are improved in initial stiffness by 24%-41%， bearing capacity by 29%-36% and energy dissipation capacity by 7%-17%， indicating that PEC braces have excellent seismic performance. Based on the results of the experiment， the nonlinear finite element analysis was carried out by ABAQUS software. The geometric nonlinear behaviors such as local buckling and global buckling are observed in finite element models， and the results such as peak load and yield load are in good agreement with the experimental results （the error is within 10%）. The finite element analysis shows PEC braces yield earlier than the PEC frame， which is the expected failure sequence. Additionally， the stress concentration and local buckling of joint of brace can be effectively inhibited by setting concrete or stiffeners on the web.

The mechanical properties of the axial compression members of the double-shear splicing main members were studied through 10 sets of axial compression tests. The effects of different bolt connection lengths （120 mm， 180 mm and 240mm） and steel-clad area ratios （1.08， 1.22 and 1.31） were investigated. The ultimate failure mode， ultimate bearing capacity and load-displacement curve of the test members were compared and analyzed. The experimental results show that the ultimate failure mode of the angle steel main members without splicing joints is the flexural-torsional buckling failure around the main axis at the mid-span section， and the out-of-plane deformation is the largest and the torsional deformation is small. When the angle steel main member adopts the double-shear splicing joint， the axial compression ultimate failure mode is divided into two cases： when the bolt connection length at the double-shear splicing joint is not more than 120 mm or the steel-clad area ratio is 1.08， the compression failure mode of the main member is mainly mid-span cross-section flexural-torsional buckling， accompanied by the failure of the splicing joint. When the bolt connection length is greater than 120 mm and steel-clad area ratio is greater than 1.08， the compression failure mode of the splicing main member is the coupling failure of the flexural-torsional buckling at the mid-span near the joint and the local buckling at the inclined member. Combined with the test results， the existing calculation methods of the standards are demonstrated and analyzed， and the structural design suggestions of L125×10 angle steel main member are given. The research conclusions are conducive to promoting the development of transmission line structure design technology and laying a technical foundation for the compilation and improvement of transmission line structure design specifications.

In order to explore the determination of the number of strengthened stories and the arrangement of strengthened story components for super high-rise frame-tube structures with large aspect ratios， and to obtain a strengthened story layout plan that can meet the structural needs while minimizing the adverse effects of vertical stiffness and internal force mutations caused by the strengthened story， the T2 tower of Qingdao Haitian Center is taken as the research object， and a three-dimensional structural model is established based on ETABS software for analysis. After comparing the traditional scheme of arranging strengthened stories with improved schemes， a setting principle of strengthened story of super high-rise frame-tube structure with large aspect ratio based on this structure is proposed.The outrigger trusses and waist trusses are arranged in the direction with low stiffness， while the outrigger trusses are not arranged in the direction with high stiffness， and waist trusses are only set within the end spans. This approach not only can meet the structural demands of lateral displacement and inter-story drift， but also can reduce the abrupt change of inter-story drift and internal force. At the same time， the stiffness difference between the two main axes at the strengthened story is reduced， which is most beneficial to the structure.

In order to solve the problems of serious pollution and low construction efficiency caused by on-site welding of concrete-filled steel tubular column-column connection joints， and to integrate the advantages of cross-shaped core tubes for convenient processing and construction， a new type of connection joint is proposed. This joint is a fully bolted assembly connection joint with built-in cross-shaped core tube for concrete-filled square steel tubular （CFSST） columns， based on the self-tapping bolt and core tube column joint proposed by the research group. Based on the proposed static test results of this connection joint， a numerical analysis model is established using ABAQUS software to verify the reliability of the simulation method， and a parametric analysis is carried out for the different combinations of self-tapping bolts， stiffening ribs and cross-shaped core tube. The results show that the numerical analysis results are in good agreement with the test results， which verifies the reliability of the numerical analysis method. The self-tapping bolts effectively inhibit the buckling deformation and relative opening of the flange plate， which increases the joint bending capacity by 19.94% on average， and slows down the stiffness degradation of the joint. The stiffening ribs inhibit the deformation of the flange plate， which increases the joint bending capacity by 3.70% on average， but increases the possibility of relative opening. The cross-shaped core tubes effectively inhibit the buckling deformation of the flange plate and the local buckling of the column wall， increasing the bearing capacity and stiffness， and delaying the stiffness degradation of the joint. Overall， the stiffening ribs have little effect on the bending capacity of the joint， and increase the relative openings of the upper and lower flange plates. Therefore， the fully bolted assembly joint for CFSST columns can be optimized as a combination of core tube and self-tapping bolts， and the cross-shaped core tube， self-tapping bolts and concrete have a good mechanism of synergy. Both the joints before and after the optimization can achieve the performance design goal of "strong joints， weak members"， which are recommended in the engineering application.

This paper proposes a new type of steel-bars truss deck with permanent bottom form （PFCB-steel-bars truss deck）， which is an assembled floor deck consisting of steel-bars truss and permanent fiber cement bottom （PFCB） prefabricated with self-tapping screws and connectors. In order to study the structural performance of PFCB-steel-bars truss deck in the construction stage and to consider the influence of moisture in concrete mortar or precipitation weather on fiber cement bottom form during construction， a compressive capacity test of PFCB-steel-bars truss deck was conducted under water-saturated condition. A parametric analysis of the steel-bars truss deck structure was carried out using finite element software simulation， and the change rule of ultimate bearing capacity and stiffness was obtained. The results demonstrate that the PFCB-steel-bars truss deck has good performance under uniform design combination load and concentrated load， and the deflection of the specimens with a span of 3 600 mm is controlled to be between 6-8 mm under the ultimate load. Moreover， the change of the self-tapping screws spacing and the height of the steel trusses has a more obvious effect on the load bearing capacity of specimens.

The complex structural behaviors in steel spiral staircases， due to their unique and irregular structures， render traditional linear analysis methods inadequate for accurate prediction of structural responses and stability design， particularly in determining effective lengths. This study employs the direct analysis method （DAM） to overcome these limitations， taking into account the overall structural and member initial imperfections， thus providing an efficient and safe approach for the analysis and design of such structures. A specific engineering project is presented as a case study， utilizing NIDA software to perform a stability investigation via DAM， with results compared against those obtained through linear analysis. The research examines the mechanical responses under full-span loading， left and right half-span loading， and various live load distributions across different sectors， as well as the impact of varying support conditions on the staircase structure. The findings indicate that the maximum component stress determined by DAM exceeds that of first-order linear analysis， with a maximum utilization factor reaching 0.993， and a corresponding vertical displacement that is even more significant， peaking at 0.348 m， confirming the importance of second-order effects. In the design of steel spiral staircases， adverse distributions of live loads， especially under left half-span loading conditions， should be given special consideration. For live load distributions， the impact is greatest in sectors 3 and 4， located at the mid-span of the staircase. Moreover， increasing the stiffness of the top support contributes to a reduced stress ratio while also leading to an increase in bending moments due to second-order effects. This research plays a significant role in guiding the analysis and design of steel spiral staircases.

In this paper， a novel four-side connected steel plate shear wall （SPSW） with circular dents is proposed. The hysteretic behavior of the SPSW with circular dents was compared with that of plane SPSW and SPSW with circular hole through numerical simulation. The effects of dent diameter， dent spacing， dent depth， steel plate thickness， steel strength and dent arrangement type on its hysteretic behavior were systematically investigated. The results show that the lateral stiffness and strength of SPSW with circular dents are between those of plane SPSW and SPSW with circular holes. By optimizing dent arrangement， the reasonable matching of lateral stiffness and strength could be realized. The relative parameters， including steel plate thickness and steel strength， play a significant effect on the mechanical behavior of SPSW with circular dents， and the lateral strength of SPSW with circular dents increase with the increase of steel plate thickness and steel strength. The other parameters， such as dent diameter， dent distance， and dent depth， play a certain influence on its mechanical behavior. The lateral strength of SPSW with circular dents takes on the decreasing tendency with the increase of dent diameter， and the lateral stiffness and strength of SPSW with circular dents exhibit the increasing tendency with the increase of dent distance. The lateral stiffness and strength of SPSW with circular dents exhibit the decreasing tendency with the increase of dent depth， but its energy dissipation capacity increase. The effect of dent arrangement on its hysteretic behavior， lateral stiffness and strength is not obvious.

A light steel-steel fiber recycled concrete composite column （SFRC composite column） was proposed. In order to study the axial compression performance of the composite column， five groups of short column specimens with varying configuration were tested， including one group of steel column specimens and four groups of composite column specimens. The effects on the failure characteristics， load-displacement curves， bearing capacity， stiffness and ductility of composite columns were studied with the parameters of section configuration， steel fiber content and recycled concrete strength. The results indicate that the SFRC composite column enhances the stability of the light steel column and substantially increases its bearing capacity. The bearing capacity of SFRC composite column increases with the addition of steel fiber. Steel fiber can restrain the crack development of recycled concrete and reduce the damage and stiffness degradation of specimens. The bearing capacity of composite column increases with the increase of recycled concrete strength， but the ductility decreases accordingly. A formula for calculating the compressive bearing capacity of SFRC composite short column has been established based on the code.

In order to simulate the cyclic behavior of double skin composite wall （DSCW） under earthquake excitations， a uniaxial material model， named CFSTsteel， that could capture the local buckling effect and fracture of steel plate was proposed. This model can implicitly simulate the cyclic hardening and softening of steel plate under cyclic loading， which exhibit path-dependent characteristics due to local buckling. Based on the OpenSees software， the fiber model of DSCW was established. The proposed fiber model of DSCW was employed to predict the cyclic behavior of DSCW specimens under maximum considered earthquake loading protocol. The simulate results showed that， compared to the traditional uniaxial material model Steel02， which does not consider cyclic deterioration， the predicted results using CFSTsteel could more accurately capture the cyclic deterioration of stiffness and strength of DSCW under cyclic loads. The proposed uniaxial material model has been implemented in the Open System for Earthquake Engineering Simulation （OpenSees） platform.

By combining an existing concrete frame with a Y-shaped eccentrically steel brace， an innovative existing reinforced concrete-Y-shaped eccentrically steel brace structure with high lateral stiffness， good seismic performance and seismic resilience capacity was developed， and the existing concrete beam-shear link （ECB-SL） composite connection was a key point to achieve the expected seismic performance of the innovative structure. In this paper， specimens with endplate connection， U shape-side plate connection， U shape-angle connection and U shape-three side bolted connection， respectively， were studied by the cyclic loading tests， and the failure modes， hysteresis curves， skeleton curves， secant stiffness， energy dissipation capacity and load-strain curves were investigated. The test results show that the unexpected failure modes of specimens were anchor bolts tension or concrete cracking， so these composite connections cannot have enough bearing capacity. Specimen experienced a failure mode of link yielding， link buckling， concrete cracking， crack propagation， and link fracture. The failure mode， overstrength factor and inelastic rotation of the specimen were the same as those of the pure very short shear link， which was recommended in the design of ECB-SL composite connections.