Interstory Drift Angle Research Articles

Effect of connection modes on seismic responses of a diaphragm wall-subway station system subjected to mainshock-aftershock sequences

Most existing seismic behavior analyses of underground structures simply consider a single earthquake. Meanwhile, the diaphragm wall, as an enclosure structure, is regarded as a security reserve and is always ignored in current studies. Herein, the characteristics of a diaphragm wall-subway station system with different connection modes under earthquake sequences were investigated using numerical simulation. The damage degree of the structural component was calculated through quantitative analysis of the tensile damage picture. The seismic damage level of the station structure was evaluated to characterize the damage transition effect induced by the aftershock according to the inter-story drift angle. Moreover, an empirical model for predicting the inter-story drift angle with respect to different peak accelerations was proposed. The research results indicate that the effect of the connection mode between the sidewall and the diaphragm wall on the damage evolution and deformation behavior of the station structure is significant. Compared with that of the compound wall structure, the seismic damage to the sidewall of the composite wall structure is much less severe, but the slabs become more vulnerable and suffer more severe damage. The accumulative damage triggered by aftershocks aggravates the extent of structural damage and even leads to damage transition. The conclusions illustrated in this paper contribute to a better understanding of the seismic resistance design of diaphragm wall-subway station systems under earthquake sequences.

Comparative analysis of seismic isolation effects under three-way seismic actions for suspension core-tube structure and frame core-tube structure

In this paper, the suspension core-tube structure and frame core-tube structure are taken as the research objects, and the modal analysis of them and their basic seismic isolation structures are carried out firstly to explore the self-vibration characteristics and seismic isolation effect of the structures. Secondly, the nonlinear time-history analysis of the four structures under the action of rare earthquakes in the X, Y, and Z directions is carried out, and their inter-story drift angles, inter-story shear forces, base shear forces, maximum accelerations at the apex of the core-tube, and cantilever beam stresses are analyzed comparatively. Finally, the displacements and loads of the energy dissipators, the maximum horizontal displacements and tensile and compressive stresses of the seismic isolation bearings are analyzed to evaluate the performance of both of them under rare earthquakes. The results show that the suspension core-tube structure and the frame core-tube structure with base seismic isolation bearings can provide good control of their inter-story drift angles and internal forces, etc. The suspension core-tube structure is superior to the frame core-tube structure in controlling the maximum acceleration at the apex of the core tube response.

Seismic Isolation Layout Optimized of Mid-Rise Reinforced Concrete Building Frame Structure

Seismic isolation technology plays a crucial role in enhancing earthquake resistance and mitigating disasters for building structures. In this study, the ETABS analysis software V21.0.1 is utilized to establish a numerical model of a six-story steel reinforced concrete frame structure. Both the time-history analysis method and response spectrum method are employed to calculate the seismic response of the model under earthquake actions. The placement of an isolation layer on the foundation and from the first to fifth floor is considered, with separate calculations conducted for each scenario. Subsequently, a comprehensive comparison and analysis of the dynamic response characteristics among different design schemes are performed. The results demonstrate that the most favorable isolation effect is achieved when the isolation layer is implemented on the foundation or first floor. Compared to non-isolated structures, the natural period of the structure can be extended by 2.2 times and 2 times under the base isolation and first-floor top isolation schemes, respectively. The damping coefficients can reach 0.35 and 0.36, respectively, while the inter-story drift angles can be reduced by 66% and 67%, respectively.

Composite floor slab effect on seismic performance of steel-framed-tube structures with shear links

High-strength steel-framed-tube structures with low-yield-point shear links (SFT-RLYPSL) exhibit exceptional lateral and torsional stiffness, coupled with significant energy dissipation capacities. This study aims to investigate teh influence of composite floor slabs on the seismic performance of these structures. Expanding on previous research concerning SFT-RLYPSL, this paper presents a simplified numerical model for the SFT-RLYPSL, incorporating the influence of the composite floor slab. The developed model employs the steel4 constitutive relation to accurately depict the behavior of low-yield-point steel. Furthermore, the simplified numerical model utilizes two-node link elements to simulate shear links and integrates composite beams to represent the influence of the composite floor slab. Using this simplified model, elastic-plastic pushover analysis is performed on five distinct SFT-RLYPSL structural cases, and nonlinear time-history analysis is conducted on three structural configurations. The investigation explores various aspects of the seismic performance of SFT-RLYPSL, including modal behavior, pushover curves, progression of overturning failure, time-history roof displacements, inter-story drift angles, base reactions, inter-story shear, failure modes, residual inter-story drift angles, and the manifestation of shear lag phenomena. The findings suggest that incorporating the composite floor slab effect enhances initial stiffness and peak load capacity in pushover analysis, leading to distinct three-stage pushover curves. During nonlinear time-history analysis, the composite floor slab effect increases structural stiffness, decreases roof displacements and inter-story drift angles, while simultaneously increasing base reactions, worsening component damage, and raising collapse risk. Nevertheless, its influence on residual inter-story drift angles remains relatively minor, with a mitigating effect on the shear lag phenomenon. Importantly, the degree of this impact varies with alterations in floor slab thickness and seismic intensity, highlighting the critical importance of considering the composite floor slab effect in structural design deliberations.

A Building Structure Health Monitoring System Based on Inter-Story Drift Angle Measured by Low-Cost Sensors

<p>大地震後為了檢查建築物是否有損壞及保護結構免於因餘震再次破壞，通常會以人工巡檢的方式判斷建築物是否安全，但因需勘查棟數太多致常造成誤判與恢復時間大幅增加的情況。近年來，地震監測網絡已推廣到使用於建築物健康監測上，以便能夠在震後第一時間檢測出損傷位置及破壞程度，快速地進行補強及救災的動作。目前常用的結構健康監測(Structure Health Monitoring, SHM)系統多使用傳統加速度計，但加速度計系統價格昂貴且強震資料易受汙染，因此使得建築物SHM的推廣受到限制，本研究提出低價格的傾斜儀做為SHM之量測設備，可改善上述問題。本研究先透過SAP2000軟體分析某三層樓構架，了解構架之變形特性，且推論出傾斜儀能夠裝設在柱中間做為量測點，可直接測得層間變位角。再研究如何快速判斷建築物各樓層之健康狀況，並且計算出傾斜儀之誤差值。也將此結果應用在2023日本E-Defense足尺十層樓鋼結構振動台實驗，將傾斜儀安裝在受損機會較大之樓層2至5樓。結果顯示出，在沒有破壞發生時，結構沒有殘餘轉角產生，且層剪力對轉角圖為直線；而當結構有破壞發生，會有明顯殘餘轉角以及層剪力對轉角歷時圖會有迴圈發生，跟數值分析之結果類似，故可知道本研究建議之健康監測方法確實可行且具有經濟可行性。</p> <p> </p><p>After a major earthquake, to check for damage in buildings and protect structures from aftershock damage, manual inspections are usually used to determine whether buildings are safe. However, due to the large number of buildings need inspection, misjudgment may occur and recovery time are often delayed. In recent years, building level monitoring networks have been promoted for building health monitoring, which can detect the location and degree of damage immediately after an earthquake, and quickly carry out retrofit work. The common structural health monitoring (SHM) systems use traditional accelerometers for monitoring, but they are expensive and the data of strong earthquake may be polluted. This study proposes a low-cost tiltmeter for SHM, which can improve the extent of above problems. This study first analyzed a three-story building structure using SAP2000 to understand its deformation characteristics, and infer that the tiltmeter can be installed at the mid-height of the column, which can directly measure the Inter-story Drift Angle (IDA) and quickly determine the building health status. We then applied this theory to a 10-story steel structure test program of E-Defense in Japan in 2023, the MEMS tiltmeter was installed on the four floors with a high chance of damage. The results show that if no damage occurs, there is no residual IDA, and the Story Shear-IDA diagram is a straight line. When damage occurs, there is a residual IDA and a hysteresis loop on the Story Shear-IDA diagram.</p> <p> </p>

The effect of an improved passive bumper on the seismic response of the base-isolated structure: Numerical simulations and optimization design

In this paper, a passive bumper, called Flexible Limit Protective Device (FLPD) which was proposed by the author before, was improved to better control the seismic response of the base-isolated structure when the isolation layer exceeds its limit deformation. To distinguish from the FLPD, the improved FLPD is called a Flexible Energy Dissipating Device (FEDD), and the FEDD has stronger dissipation capacity than the FLPD. Above all, the compression behavior of FEDDs is experimentally investigated and the experiment data of FEDDs are compared to that of FLPDs. Subsequently, the nonlinear model of FEDDs is obtained and verified using the experimental data. This obtained model was used to study the effect on the seismic response of the base-isolated structure (multi-degree-of-freedom system), namely isolator displacement and inter-story drift angle. An elite non-dominated sorting algorithm method (NSGA-II) is applied to optimize the design of FEDDs, the gap between isolators and FEDDs and stiffness of FEDDs. Finally, the seismic response of base-isolated buildings equipped with FEDD with optimal parameters is numerically simulated. The results show that FEDDs with optimal parameters can effectively reduce the isolator displacements, and keep the inter-story drift angle within the safe range when the isolation layer exceeds its limit deformation during earthquakes.

Experimental investigation of rigid khorjini connections using reduced beam sections with diagonal and horizontal-vertical stiffeners

Steel structures with khorjini beam–column connections, used to be a popular construction practice in Iran. This paper presents a new rigid khorjini connection with reduced beam sections (RBS) for earthquake-resistant steel structures. In rigid khorjini connection, two beams pass next to the column faces without interruption and are connected to the column by vertical plates. In this research, Rigid khorjini connections with Reduced beam sections were investigated. RBS method has some disadvantages such as web local buckling and lateral torsional buckling. Therefore, to prevent these weaknesses and improve the performance of khorjini connections with reduced beam sections, web stiffeners were employed. Four different specimens were constructed and tested using IPE 140 profiles for beams: one without an RBS (KHORJINI), one with reduced beam section (KRBS), and two with RBS and web stiffeners (KRBS-HVS and KRBS-DS). Through these experimental tests, it was revealed that all specimens sustained the interstory drift angle greater than 0.06 rad without any significant loss of strength, which indicates that the Rigid khorjini connection with reduced beam sections for IPE140 profiles can perform acceptably under the conditions of AISC regulations and the use of Diagonal and Horizontal-Vertical stiffeners increased the energy dissipation and plastic rotation capacity of connections.

EXPERIMENTAL RESPONSES OF HIGH-STRENGTH KC COLUMN WITH LARGE AXIAL LOAD

A kernel-confined (KC) column, which a reinforced-concrete (RC) column moves partial longitudinal reinforcements from conventionally placed on outer periphery of section to inner kernel-confined region (KC bar), was concerned in this paper. This paper mainly intended to investigate seismic behaviors of the KC column with large axial loads. There are six sets of high-strength RC column specimens with 600 mm × 600 mm in section to be conducted. Their design strength of concrete was 70 MPa, and steel grades of SD550W and SD790 were designed as the longitudinal and transverse reinforcements, respectively. The number and location of the KC bar and the number and strength of transverse reinforcement are key study parameters. Test results indicated that for all specimens, including KC columns, the testing maximum moments were larger than the computed moment from ACI model and their average value of overstrength ratio of the testing to the computed was 1.25. In addition, the strength obtained from the XTRACT software had a better prediction with an average error of 0.99. Based on test deformation results for all specimens, the amount of the confined reinforcement per ACI 318-19 with an axial load of 0.5fc’Ag, can provide 3% radian of inter-story drift angle capacity for the high-strength RC column.

Seismic response of CFST Double-Tee moment connections: Design criteria and experimental tests

The unsymmetric prying response of the T-stub flange of Double-Tee connections with Concrete-Filled-Steel-Tube and Through-Bolts (CFST-TB) is investigated in the present article. A design method is presented and discussed to enhance the ductility of the connections accounting for the Unsymmetric Prying Action (UPA) and the longitudinal strain of the through bolts. Two joints have been alternatively designed in accordance with AISC-358 and the proposed rules and also tested to evaluate and compare their performance and failure mode. Finite element models have been validated against the experimental results and finite element simulations have been carried out to assess the local response of the considered joints. The results indicated that the performance of the AISC358-compliant specimen was affected by through-bolt fracture and damages to the T-stub segment at the first cycle of 0.04 rad interstory drift angle. The UPA-compliant specimen had a satisfactory performance without any damage to the connection components until 0.06 rad interstory drift angle. Therefore, experimental and numerical results showed that the proposed criteria can guarantee an effective and ductile response of CFST-TB Double-Tee connections.

RC建物の地震時の損傷が発生させる労務量と層間変形角の関係性に関する基礎的研究

In order to evaluate repairability (i.e., repair time and repair cost, etc.), it is necessary to estimate the amount of labor (person-day) for repair caused by seismic damage. The purpose of this study is to obtain the fundamental information necessary for establishing the relation model between the labor amount L per unit floor area and the inter-story drift angle R (i.e., L-R model). We analyze the effects of the amount of structural and non-structural components and the failure mode of the structural members, on the L-R relation, and discuss the feasibility of establishing a L-R model for repairability evaluation.

Study on seismic vulnerability analysis of the interaction system between saturated soft soil and subway station structures

The seismic vulnerability of interaction system of saturated soft soil and subway station structures was explored in this paper. The coupled nonlinear numerical models of interaction system were established using the u–p formulation of Biot′s theory to describe the saturated two-phase media. A refined finite element model of interaction system was developed to study its nonlinear seismic responses and seismic hazard mechanism. In this study, the multi-yield elastoplastic constitutive model was adopted for the soil, while a fiber section elastoplastic constitutive model was used for the structure. The seismic response of the structure was calculated by inputting the artificial seismic wave obtained from the power spectrum-triangular series method. The maximum inter-story drift angle was taken as a structural performance parameter for the subway station structure. The structural demand cloud was obtained under random ground motion sequences. Based on the probabilistic seismic demand model analysis method, the seismic vulnerability curve of the subway station structure was plotted, and the seismic vulnerability curve was analyzed as per the vulnerability of performance parameters. With the increase of soil strength, the vulnerability index of subway station structure under different peak acceleration ground motion decreased correspondingly. Based on the above vulnerability theory and analysis methods, it can be found from the above vulnerability theory and analysis methods that the subway station structure with established buried depth in saturated soft soil site exhibits a certain degree of safety and reliability, and can meet the seismic fortification goal of "no damage in small earthquakes, repairable in medium earthquakes and no collapse in large earthquakes". The results of vulnerability analysis are in line with the actual seismic survey, and the vulnerability analysis method proposed in this paper can be applied to the vulnerability analysis of underground structures on saturated soft soil foundation.

Evaluation of Seismic Acceleration Demands on Mechanical Support Systems

Earthquakes are among the most influential force of nature that affect human life. Reconnaissance after the severe earthquakes pointed out that seismic performance of non-structural members and elements could be as significant as the structural members in lateral force-resisting systems. As such, it is important for design engineers to recognize the seismic demand on the mechanical systems that support the critical non-structural components (e.g., sprinklers, electrical and mechanical equipment, etc.) in terms of the safety during and after an earthquake as well as functionality and retrofitting cost after an earthquake. The primary goal of this study is to systematically investigate the seismic demands on the mechanical support systems of a typical mid-rise steel structure. For this purpose, non-linear time history analyses are carried out using a suite of ground motion acceleration records to evaluate the seismic demands on both seismic force-resisting system and the support system by means of inter-story drift angle and horizontal accelerations, respectively. Results obtained from the analyses are discussed considering the requirements stipulated in the current national and international buildings and recommendations are made.

Seismic Response of Star-Type Grid Concrete Wall Structure by Numerical Modeling.

Cement polystyrene shell mold (CPSM) grid concrete walls have been widely applied in the construction of low and mid-rise buildings with higher load-bearing and insulation properties. A star-type grid concrete wall was constructed based on the infill wall simplified to an equivalent diagonal bracing model. To investigate the seismic responses and behavior of a star-type grid concrete wall structure, an overall time-history numerical simulation was carried out in this paper. Typical results, including acceleration, deformation, hysteresis curve and failure pattern of this novel construction system, were interpreted. Results indicate that the star-type grid concrete wall structure has satisfactory seismic performance, including energy dissipation capacity. The structure has higher lateral stiffness and can work in an elastic state under major earthquakes. Accordingly, it is more sensitive to near-fault ground motion with higher frequency components. Meanwhile, the structural inter-story drift angle is less than the limit value of lighter damage when subjected to a super-major earthquake, and the structure presents shear deformation. The openings significantly affect the failure mode, the star-type grid concrete wall with a window (a small aspect ratio less than 1.11) conforms to shear failure, and the wall with a door (aspect ratio of 2.5) conforms to bending-shear failure. The diagonal bracing can distribute the stress in the wall, especially the concrete lattice beam, and effectively resist the lateral forces via the concrete lattice column, improving the ductility and integrity of the structural system.

Seismic performance evaluation of Y-shaped eccentric brace–high-strength steel frame structure based on remote collaborative hybrid test

A remote collaborative hybrid test (RCHT) system based on the OpenFresco platform was established. The seismic performance of the Y-shaped eccentric brace–high-strength steel frame (YEB–HSSF) structure was evaluated via the RCHT loading of a multistory and multi span YEB–HSSF model with two test substructures at different locations. The test phenomena and results showed that the maximum inter-story drift angles of the RCHT model were 0.0018 and 0.0077 rad under frequent-intensity and rare-intensity earthquakes, respectively, which satisfies the requirements of GB 50011-2010. Under the action of a rare intensity earthquake, the webs of the test substructure links preferentially entered the yield state with shear deformation, whereas the other members remained in the elastic state; this conforms with the design concept of damage-controllable structures. Finally, a finite-element pure numerical model corresponding to the RCHT model was established to further evaluate the seismic performance of YEB-HSSF structure. The results showed that the base shear distribution ratio resisted by the HSSF part in the global model tended to increase with increasing peak ground acceleration. Under the action of a rare 9 intensity earthquake, the shear links were close to the ultimate bearing capacity, and the shear distribution ratio resisted by the HSSF part exceeded 40%. This indicates that the YEB-HSSF structure satisfies the design requirements for dual systems based on GB 50011-2010.

Seismic performance of prefabricated semi-rigid RCS structures

To study the seismic behavior of prefabricated reinforced concrete column-steel beam (RCS) hybrid structures, a cyclic loading test on a novel RCS joint was conducted to investigate the failure modes, ductility, and energy dissipation. The moment-rotation relationship model of the joint was proposed according to the test. Furthermore, the model of a 3-bay, 5-story semi-rigid prefabricated RCS frame was established in SAP2000 software. The modal analysis and dynamic elastic–plastic analysis were carried out on the semi-rigid and rigid RCS frames respectively to study the effect of semi-rigid connections on the seismic performance of RCS structures. Analysis results show that the failure mode of the prefabricated RCS joint meets the strong column-weak beam requirement. The ‘bow’-shaped hysteretic curve indicates the joint has good seismic performance with good ductility and energy dissipation capacity. Compared to rigid RCS structures, semi-rigid connections lead to a reduction in the overall stiffness and an increase in the natural vibration periods of the structure. Under the action of the earthquake, the base shear force of the semi-rigid RCS structure is smaller than that of the rigid RCS structure. The maximum inter-story drift angles and top displacement of semi-rigid RCS structures will increase, but still meet the requirements of the seismic standard.

Seismic behaviour of novel self-tightening one-side bolted joints of prefabricated steel structures

In response to the requirements of building industrialization and sustainable development, prefabricated steel structures are vigorously promoted in recent years. The joint is an important part of prefabricated steel structures. The response of the structures under earthquake is directly determined by the seismic behaviour of the joints. Square steel tube columns and H-section steel beams are widely used in prefabricated steel structures due to the superior mechanical properties. Nevertheless, the bolted joints need to be operated on both sides. To solve this problem, a novel self-tightening one-side bolt (STOSB) was proposed based on the self-tightening high strength one-side bolt (SHSOB) developed by our research group. The behaviour and failure mechanism of the prefabricated steel structure joints based on the STOSBs under the low cyclic loading were revealed. Based on the existing experimental research, the finite element software ABAQUS was used to establish the refined numerical models of three fabricated steel joints. The numerical simulation analysis was carried out to verify the practicability of the STOSBs in practical engineering. The equivalent viscous damping ratio ζ - inter-story drift angle θ curve, hysteretic curve and skeleton curve of each specimen were obtained. On this basis, a parametric analysis was carried out to explore the effects of the column flange thickness, column diaphragm plates, endplate thickness, endplate stiffeners and other factors on the seismic behaviour of this novel joint. Subsequently, according to the moment - rotation hysteretic curves determined by the finite element analysis, a restoring force model of this novel joint under the low cyclic loading was established. The results show that the STOSBs can be used in practical engineering. The failure mode of each specimen is that a plastic hinge appears in the steel beam above the stiffeners. The endplate is always close to the column flange during the test. The seismic behaviour of the joint is significantly influenced by the endplate stiffness and column flange thickness. The bearing capacity, energy dissipation and rotational stiffness of the joint are enhanced with the endplate stiffness and column flange thickness increasing. Setting diaphragm plates in the steel column opposite to the upper and lower flanges of the steel beam can achieve similar results. When the stiffness of the endplate or column flange is weak, the moment - rotation hysteretic curve is full and the joint is a semi-rigid joint. When the stiffness of the endplate and column flange is strong, the moment - rotation hysteretic curve is in an elastic range and the joint is a rigid joint. The hysteretic behaviour of such joints under the low cyclic loading can be well simulated by the restoring force model established herein.

Importance Analysis of Structural Seismic Demand Based on Support Vector Machine

Seismic demand analysis of structures plays an important role in the structural seismic calculation; however, studies on the importance analysis of seismic demand are limited. A new method based on a support vector machine (SVM) is proposed to analyze the importance of structural seismic demand and study the influence of random variables on structural seismic demand in this study, where the linear kernel function, Gauss kernel function, and polynomial kernel function are used in SVM. The time history analysis of the steel-reinforced concrete (SRC) frame structures has been carried out by the finite element software OpenSees under the action of different seismic records. Four kinds of seismic demand of the SRC frame structure are analyzed in this study, which are top displacement, maximum floor acceleration, base shear, and maximum interstory drift angle, respectively. Importance indexes of the four kinds of structural seismic demand are in good agreement with those of the Monte Carlo (MC) numerical simulation method and Tornado graphic method, which verify the accuracy of the proposed method. Moreover, the sample size of the proposed method is greatly smaller than that of the MC method. Therefore, the computation efficiency has been improved significantly by the proposed method.

Shaking table testing of the reinforced concrete staggered slab-column structure

In order to study the seismic performance of the reinforced concrete staggered slab-column structure, one 1/7 scaled test specimen was fabricated and tested. The acceleration response, displacement distribution, dynamic characteristics, torsion responses, failure mechanism, shear force, and strain of test specimen were measured and evaluated. Test results indicated that the natural frequency and acceleration magnification factor of the test specimen gradually reduced, while the floor shear force and torsion response gradually increased. Meanwhile, the maximum inter-story drift angle of test specimen in the elastic and elastic-plastic stage was 1/196 and 1/78, respectively, indicating that the lateral stiffness of staggered slab-column structure was relatively small. The inter-story angles of the second and fifth floors were larger than adjacent floors. It was suggested that the stiffness of the test specimen was inhomogeneously distributed due to staggered slabs and a lack of frame beams. The damage of columns between staggered slabs was obviously larger than other columns. The plastic hinges were successively observed at slab-column junctions on the first and second floor and bottom of columns. Finally, the plastic hinges at slab-column junctions lost their capacity, followed by plastic hinges at the bottom of columns, and the test specimen collapsed. The failure process of the staggered slab-column structure exhibited undesirable brittle failure mode. Based on the experimental results, several design suggestions were proposed to improve the overall seismic behavior of the staggered slab-column structure. Such comprehensive research helps enhance understanding of this newly developed type of structure.

Low-rise steel moment frames with energy-dissipating exterior walls: Computer modelling and seismic performance assessment

This research focused on a new type of energy-dissipating exterior wall system for enhancing the seismic performance of low-rise steel moment-resisting frame (MRF) buildings. The computer model for the energy-dissipating exterior wall system was developed based on simple elements and existing material models. Adequacy of the computer model was confirmed by the published test results. To address how the exterior wall system would affect seismic performance of low-rise steel MRF buildings, a representative 2-story MRF demonstration building was selected. The exterior wall system was introduced in the demonstration building for rehabilitation purpose. Computer models for the original and rehabilitated systems were developed. Based on the results from computer simulations of the original and rehabilitated systems, it was found that the energy-dissipating exterior wall system can reduce both transient and residual inter-story drift angle responses in the demonstration building. Moreover, based on the analysis results, a useful criterion denoted as the equal-energy rule was established for future design of the exterior wall system to achieve the intended transient inter-story drift angle responses allowed by a certain performance objective in low-rise steel MRF buildings.

Seismic performance of prefabricated middle frame composed of special-shaped columns with built-in lattice concrete-filled circular steel pipes

Prefabricated buildings are green and environment-friendly, with high construction efficiency. Concrete-filled steel pipe structures have high bearing capacity and strong deformation ability. Special-shaped column frame structures of prefabricated concrete-filled circular steel pipe with built-in lattice can give full play to the advantages of prefabricated buildings and concrete-filled steel pipe structures, with the advantage of high space utilization rate of special-shaped column structures. In order to study Seismic performance of frame in special-shaped columns of prefabricated concrete-filled circular steel pipe with built-in lattice, a full-scale middle frame model specimen with two floors and two spans was designed, and the failure mechanism of the specimen was obtained by low-cycle loading test. The hysteretic performance, deformation capacity, energy dissipation capacity and stiffness degradation of the specimen were analyzed. The results showed that the failure mechanism of the prefabricated concrete-filled steel tubular special-shaped column is a typical beam hinge mechanism, which meets the design requirements of “strong column and weak beam”. The special-shaped columns frame of built-in concrete-filled circular steel pipe has full hysteretic curve, good ductility and energy dissipation capacity, and stable stiffness degradation. When the specimen is damaged, the inter-story drift angle reaches 1/23, which is much higher than the limit requirement of elastic–plastic inter-story drift angle of 1/50 under strong earthquake. The existence of built-in concrete-filled steel pipe changes the bearing mechanism of the structure. After the external concrete falls off, the internal force of the structure redistributes, forming a stress system of built-in concrete-filled steel pipe truss. The post-cast joint between overlapping precast column and superposed beam and grouting connection joint between precast column and column sleeve are not damaged, and the fabricated joints are safe and reliable.