Elastic-plastic Time-history Analysis Research Articles

Study on seismic performance of prestressed fabricated reinforced concrete frame structure assembled by steel sleeves

This paper introduces a novel type of prestressed fabricated reinforced concrete frame (PSFRC frame) structure, which utilizes steel sleeves for assembly. The PSFRC frame incorporates prestressed tendons, stiffened steel sleeves, and high-strength bolts, resulting in improved bearing capacity and assembly efficiency. To assess the seismic performance of the PSFRC frame joint, experimental tests were conducted on one reinforced concrete (RC) joint and two PSFRC frame joints under cyclic loading. Hysteresis analysis and elastic-plastic time-history analysis were also performed using a finite element model. The experimental results showed that the PSFRC edge joint reached a peak load of 89.30 kN, while the PSFRC middle joint exhibited a capacity of 169.95 kN, which was 58.87 % higher than that of the cast-in-place specimen XJ (107.87 kN). The hysteresis curves of the PSFRC joints demonstrated significant fullness, with the equivalent damping coefficient of the PSFRC joint being increased by 11.56 % compared to the RC joint. Additionally, a simulation method using ABAQUS software was proposed to investigate the seismic response of the integral structure of the PSFRC frame. Finite element models for both PSFRC and RC frames were established, and their seismic performance was analyzed under cyclic loading and the El Centro seismic wave. Various parameters including peak loading capacity, stiffness degradation, peak acceleration value, inter-storey drift ratio, and concrete damage value were considered. The finite element analysis results revealed that the load-carrying capacity of the PSFRC frame (435.33 kN) was approximately 30 % higher than that of the RC frame (386.48 kN). Furthermore, at the peak acceleration of 600 gal, the maximum inter-storey drift ratio of the first floor for the PSFRC frame was 1/58, which was below the limit value of 1/50. The plastic hinge position at the beam end of the PSFRC frame was further from the core area, aligning with seismic design objectives. This research provides valuable insights into the design of fabricated building structures and methods for analyzing seismic performance.

Seismic response of a mid-story isolated stilted structure in mountainous areas

Research on the SSI effect on flat sites has yielded many valuable conclusions. However, current research on the impacts of various special local terrains on structural dynamics remains limited. For mountainous areas, it is common to construct houses in a multi-step, climbing, and laterally staggered architectural form that follows the mountain terrain. Only through the analysis of the combined action of the upper and lower parts can the seismic performance of this type of structural form be better revealed; considering the influence of SSI effects will be closer to the actual seismic effects. Therefore, to identify the damage factors of the mid-story isolated stilted structures under earthquakes and provide optimized design plans for the structures, six models are established considering three slopes and two types of foundations based on the engineering case in Chongqing, China. Through the elastic-plastic time-history analysis under earthquakes in the down and transverse-slope directions, concludes, compared with not considering SSI, the seismic response of the mid-story isolated stilted structures considering SSI in mountainous areas is amplified. With the increase of the mountain slope, the seismic response of the structures considering SSI increases, and the amplification coefficients are between 1–1.8. The amplification coefficients of the structures without SSI are concentrated around 1, which is less influenced by the slope. The damage to the stilted isolated layer is mainly concentrated in the column and the beam end, and the maximum seismic response appears in the short columns. The foundation soil stress increases with the increase of the mountain slope.

Seismic Response of the Continuous Rigid-Framed Bridge with Super-High Piers Based on Shaking Table Tests

Continuous rigid-framed bridges with super-high piers (CRFB-HP) have been widely applied in mountain areas. However, their seismic performance is still urgently to be clarified. In this study, the refined finite element model (FEM) of a CRFB-HP was constructed and verified according to the shaking table test results of its scaled model. On this basis, systematic elastic-plastic time history analysis of the CRFB-HP was conducted to investigate the influence of parameters on their seismic performance, including main bridge span, pier height and number of tie beams. The results show that CRFB-HP have the characteristic of long vibration periods and are more sensitive to long-period ground motions. Along the longitudinal and transverse directions, the peak pier top displacement and pier bottom bending moment of CRFB-HP are both relatively large under NLPL (+20~+70%) and NFPT (TP ≈ T1, +50~+120%) excitations. For the same span, the peak pier top displacement increases with the pier height increasing, while the peak pier bottom bending moment decreases with the pier height increasingFor the same pier height, the peak pier top displacement and peak pier bottom bending moment both increase with the span length increasing. Moreover, the pier height change has a greater effect on the pier top displacement than that of the span change. CRFB-HP show obvious high-order response participation (HRP) under different ground motions. The NFPT (TP ≈ T1), ground motions can significantly increase HRP. Moreover, compared with cast-in-place CRFB-HP, the HRP of a fabricated super-high pier is greater (+20~+30%). The peak pier top displacement and pier bottom bending moment both decrease with the increase in the number of tie beams. The reasonable arrangement of tie beams can improve the lateral seismic performance of CRFB-HP. However, compared to the cast-in-place CRFB-HP, the peak pier top displacement is larger, and the peak pier bottom bending moment is smaller, for the fabricated CRFB-HP.

Numerical Simulation Analysis of Seismic Performance for Framework Structure Based on Rayleigh Damping Algorithm

Seismic analysis of engineering structures can effectively ensure social and public safety, and in engineering practice. The elastic-plastic time history analysis of reinforced concrete frame structures is a more accurate analysis method for evaluating the seismic performance of the structure. According to relevant regulations, the seismic fortification intensity of a certain frame structure is 6 degrees. To analyze its seismic performance under earthquake action, this paper uses ABAQUS numerical simulation software combined with Ruili damping algorithm to establish a seismic model of the frame structure. The research results indicate that: (1) By calculating the interlayer displacement angle, the interlayer displacement angle of each layer meets the requirements of the specification, and the structure has good seismic performance. (2) The peak acceleration difference between the top layers of the structure decreases first and then increases from the bottom to the top. (3) There is a coupling relationship between structural deformation and the acceleration of the structure itself, and a coupling relationship between interlayer deformation and the peak stress at the top of the interlayer.

Research on seismic performance of corrugated web rigid structures

Abstract: Corrugated web H-beam refers to a steel beam with a wavy shape along its length, which is extensively utilized in various parts of building structures such as beams, columns, and walls. It serves the purpose of connection and support, while the corrugated or folded design enhances the shear resistance and out-of-plane stiffness of the web to some extent. However, despite their advantages including high strength, stiffness, and lightweight construction, relevant regulations stipulate that these members can only be used in lower-intensity applications or higher-intensity scenarios if specific conditions are met. One crucial condition is that the ratio between the design value of axial force subjected to seismic action and the product of the member's flange section area and steel's tensile strength should not exceed 0.4. In this study, we aim to further investigate the seismic characteristics and applicable intensity of corrugated steel structures under earthquakes through large-scale finite element ABAQUS simulations. We will observe dynamic characteristics and failure modes of corrugated rigid frame structures using elastic-plastic time-history analysis methods as well as examine plastic deformation features of steel beam members under low cyclic loads via hysteretic analysis methods. The findings demonstrate that when properly designed with reasonable beam spans, corrugated web rigid frame structures can still be employed in high-intensity areas above 7 degrees even when subjected to an axial compression ratio up to 0.5.

Analysis and Application of Double Steel Plate Concrete Composite Shear Wall in the R&D Building of Zhanjiang Bay Laboratory

The R&D Building of Zhanjiang Bay Laboratory is a high-rise structure with multiple irregular items exceeding the specification limit, employing a steel frame-shear wall structural system. The outer frame consists of square steel tube concrete columns and solid-web steel beams, while the core shear wall uses a double steel plate concrete composite shear wall. This paper employs the architectural structural calculation software YJK-EP to perform a dynamic elastic-plastic time-history analysis under rare earthquake action. The shear and bending resistance of the shear wall at the maximum shear force and bending moment are checked to meet the requirements of the “Technical Specifications for Concrete Structures of High-rise Buildings”. The maximum inter-story displacement angle meets the requirements of the “Code for Seismic Design of Buildings”. The double steel plate concrete composite shear wall Wall-1, connected to a large-span and heavy-load transfer truss, was verified under significant seismic action using the ABAQUS software. The results indicate that Wall-1 can meet the design target requirements under major earthquake conditions. Finally, a dynamic nonlinear analysis method was employed using MIDAS-GEN software to study the structure’s anti-progressive collapse performance. The results show that under seven different scenarios, the maximum rotational angle of the remaining structural horizontal members is 2.02°, far less than the limit set by GSA, indicating that a progressive collapse did not occur. In the scenario where the corner column is removed, both the maximum shear and bending moment values for Wall-1 are far below its shear and bending resistance capacities, satisfying the load-bearing requirements. The removal of the corner column has a significant impact on the displacement of the columns on the same level nearby, with the peak displacement change rate reaching 702.65%.

Application research on digital twins of urban earthquake disasters

The digital twin of an earthquake disaster city constructed using digital twin technology can reflect the data of different stages of the earthquake disaster in the virtual space and can ensure high synchronisation and simulation of the two to effectively improve the safety of emergency rescue personnel and the scientific decision-making ability of decision makers. Oblique photogrammetry matched the Light Detection and Ranging (LiDAR) data to complete a high-precision three-dimensional real-scene model. The urban digital twin model was established as a module with the three-dimensional base model generated by the two-dimensional frame data with a fast update speed. Based on the shortest-fault-distance intensity-attenuation model, the seismic intensity was calculated using a known active fault and aftershock sequence, and the applicability of this method was verified. The elastic-plastic time history analysis method was used to calculate the seismic response of the building, and the seismic damage level was visualised using a three-dimensional model. The dynamic changes of earthquake disasters are monitored by sensors in real time and analysed in a digital twin model to provide an optimal scheme for earthquake emergency rescue and accurate evaluation results of earthquake disasters.

Seismic performance and hysteretic model of corroded steel frame columns in offshore atmospheric environment

Previous studies show that the offshore atmospheric environment corrosion gradually reduces the physical and mechanical properties of steel and eventually deteriorate the seismic performance of steel structures. This paper presents a comprehensive study on the seismic performance of corroded steel frame columns in offshore atmospheric environment. Artificial climate accelerated corrosion tests and cyclic loading tests were carried out on six steel frame columns. The effects of corrosion level and axial compression ratio on the failure mechanism and seismic performance of the columns were investigated in details. The test results indicate that with an increase in corrosion level or axial compression ratio, the displacements associated with plate local buckling, plastic hinge formation and final failure tend to reduce gradually. The bending capacity, ductility and energy dissipation capacity of columns also significantly decrease, and the strength and stiffness degradation effect intensify. Furthermore, a moment-rotation hysteretic model in plastic hinge zone for corroded steel frame columns, considering the cyclic deterioration in strength and stiffness, was established by introducing a two-parameter seismic damage model. The predicted moment-rotation curves and energy dissipations coincided well with the experimental results, verifying the rationality and applicability of the proposed hysteretic model. The research results provide theoretical support for elastic-plastic time history analysis and seismic risk assessment of existing steel frame structures in offshore atmospheric environment.

Seismic performance of self-centering braced rocking frame with novel self-centering friction dampers characterized by low-secondary stiffness

Research has demonstrated that self-centering energy dissipation dampers (SCEDs) are effective devices for reducing the residual deformation of structures after a strong earthquake. However, the equivalent damping ratio of SCEDs is relatively lower than that of conventional dampers such as viscous dampers, BRBs, or friction dampers. According to displacement spectrums, the lower damping ratio could result in a lower natural period and higher equivalent stiffness of structures for a given displacement target, and thus the structures could attract more earthquake action to the structures. To alleviate the problem, a novel self-centering damper composed of elastic post-buckling plates and adjustable friction devices (PBSCFD) was proposed and used as the self-centering braces for a self-centering braced rocking frame (SBRF) structure for example. First, the theoretical force-displacement relationship of the PBSCFD was derived based on its configuration and work principle, and then a scaled PBSCFD was manufactured and tested to investigate its mechanical properties and verify the theoretical constitutive model. Subsequently, the SBRF structure with PBSCFDs was designed by the direct displacement-based seismic design method (DDBD), and its seismic performance was examined by elastic–plastic time-history analysis. Finally, the effects of the secondary stiffness ratio of the self-centering braces on seismic mitigation of the SBRF structure were investigated. The results show that PBSCFDs is characterized by classic self-centering behavior with low secondary stiffness, which can be designed to obtain significant control effects on the base/interstorey shear and interstorey drift ratio of the SBRF structure under rare and extremely rare earthquake compared to the conventional SCEDs with significant secondary stiffness.

A novel self-centering friction damper with elastic post-buckling plates to retrofit bridge bents

The self-centering energy dissipation dampers (SCEDs) have been demonstrated in mitigating the residual deformation of structures under strong ground motions. However, existing researches show that the damping force demand of SCEDs is higher than conventional dampers such as viscous dampers, BRBs or friction dampers for same design displacement of self-centering retrofitted structures, which could lead to higher base shear and acceleration responses of structures. In order to alleviate the problem, a novel self-centering damper composed of elastic post-buckling plates and adjustable friction devices (PBSCFD) was proposed. Compared with conventional SCEDs, the proposed PBSCFD has low secondary stiffness and adjustable energy dissipation capacity, which is beneficial to control the additional internal force of members adjacent to the damper in self-centering retrofitted structures. Based on the configuration and working principle of the PBSCFD, the theoretical force-displacement relationship of the damper was derived. Subsequently, a scaled PBSCFD was manufactured and tested under quasi-static loading to investigate its mechanical properties and to verify the theoretical constitutive model. In order to demonstrate the seismic performance of PBSCFDs, the double-column bridge bent retrofitted with PBSCFDs was designed by direct displacement-based seismic design method (DDBD), and its seismic performance was examined by elastic-plastic time-history analysis. Finally, effects of secondary stiffness ratio of self-centering dampers on seismic mitigation of self-centering retrofitted bridge bent were investigated. The results show that PBSCFDs have certain advantages in controlling the base shear and acceleration of the retrofitted bridge bent compared to conventional SCEDs with significant secondary stiffness.

Research on the influence of panel zone on dynamic damage of multi-story steel structure

As the most important component of steel structure, the panel zone has done a lot of research. In this article, the influence of the thickness of the panel zone on the performance of the multi-story steel frame is studied through the dynamic elastic-plastic time-history analysis of the panel zone models with different thickness. Then the appropriate thickness of the panel zone is summarised. The research conclusions are as follows: The displacement of each story is uniform and the displacement of the first story decreases after considering the influence of panel zone. While the residual deformation increases. When the thickness of panel zone is increased by three or four times, the residual deformation decreases significantly. The inter-layer displacement, plastic deformation energy, velocity conversion, maximum ductility ratio and maximum cumulative ductility ratio are closer to those of the frame model which is not consider the influence of panel zone when the panel zone is increased by three times. It concluded that the influence of panel zone should be considered, and the thickness of panel zone needs to be thickened by three or four times according to the model in this article.

Seismic Performance Analysis of Conjoined Structures with Inhomogeneous Stiffness Distribution

<p>Two or more independent towers are joined together through a connectome to form a conjoined structure. The deformation and internal force of the tower are complex, and the coupling effect between the two towers is remarkable when the earthquake is subjected. In this paper, elastic -plastic time -history analysis is adopted to research the dynamic dynamic response under the action of rare earthquakes. Moreover, in order to analyze the influence of symmetry and span parameters on the dynamic response of structures, elastic-plastic time-history analysis is carried out on structures with different symmetries, different stiffness distributions in planes and different spans.</p>

Hysteretic model and seismic energy response of CFST columns in diagrid structure

The mechanical performance of the diagrid concrete filled steel tubular (CFST) columns is significantly different from that of the traditional bending components, and very few research has been conducted on their hysteretic performance. In this study, the axial cyclic test results of eight CFST columns were presented. Based on the experimental results, the degenerate trilinear model was used to establish the dimensionless skeleton curve model, and the calculation formulas for the peak bearing capacity and the corresponding displacement of the CFST columns were proposed. On account of the observed damage characteristics of the CFST columns, different hysteretic rules were selected to establish the unloading stiffness functions in the tension and compression directions. Thus, a hysteretic model suitable for CFST columns under axial cyclic loading was proposed, and the rationality of the hysteretic model was verified by comparison with the test results. Afterwards a refined finite element model of the diagrid structure was established using the proposed hysteretic model of the CFST columns. Through elastic–plastic time history analysis, the energy distribution of the diagrid structure was studied, and the interlayer distribution of the inclined CFST columns under rare earthquakes was analyzed. The results shown that the energy had an obvious mutation at the junction between the bottom module and the secondary node layer, so it is necessary to avoid large stiffness mutations in the design of the diagrid structure.

Mechanical Behaviors of a Buckling-Plate Self-Centering Friction Damper

In order to improve the resilience of structures subjected to strong earthquakes, a buckling-plate self-centering friction damper (BPSCFD) with low post-yielding stiffness is proposed, which consists of a group of post-buckling plates and a self-centering variable friction mechanism. The damper is intended to not only reduce the peak and residual deformation of structures, but also to limit the additional internal force of the structural elements. Through theoretical derivation and finite element simulation, the hysteretic damping and self-centering characteristics of BPSCFDs are studied. In order to examine the seismic performance of the BPSCFDs, the dampers are employed to retrofit a double-columns bridge bent, and the corresponding elastic-plastic time history analysis is conducted. The results show that the force-displacement relationships of BPSCFDs with different parameter combinations are characterized by typical flag-shaped self-centering hysteretic loops and low post-yielding stiffness, and the dampers can effectively reduce the peak and residual deformation of the bridge bent without increasing the peak acceleration and base shear. The research results could supply a guideline for the design and application of the damper.

Seismic response of a mid-story-isolated structure considering soil–Structure interaction in sloping ground under three-dimensional earthquakes

A mid-story-isolated structure is developed from a base-isolated structure. Mid-story-isolated structures located in sloping ground have become a research hotspot in recent years. It is important to consider the soil–structure interaction (SSI) effects and multi-dimensional earthquakes on these structures. This paper established a model of the mid-story-isolated structure considering SSI in sloping ground. An elastic–plastic time history analysis was carried out under the one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) earthquakes. Under 3D earthquakes, the traditional 2D isolated bearing has limited damping capacity. Therefore, two kinds of 3D isolated bearings were designed. Results show that the seismic response of the mid-story-isolated structure considering SSI in sloping ground can be amplified compared with that of the mid-story-isolated structure without considering SSI. The seismic response of the structure under 3D earthquakes is more significant than that under 2D earthquakes and 1D earthquakes. For the two kinds of 3D isolated bearings, the minimum reduction rate of tensile and compressive stress is about 46% compared with that of the traditional 2D isolated bearings. When the 3D isolated bearings are used, the stress of the soil foundation decreases, which is more conducive to the stability of the soil foundation.

Seismic Performance Evaluation of a High-Rise Building with Structural Irregularities

In this study, the seismic performances of a 14-storey office building in Nanjing, China, due to its plan and vertical irregularities in the structural system, were evaluated using the response spectrum method, elastic time history analysis and elastic–plastic time history analysis. In combination of these three methods, the storey drifts and elastic–plastic states of typical structural members under three levels of earthquakes were determined to verify the robustness of the structural design program. The damage states of typical structural members at some sensitive positions were estimated and evaluated under rare earthquakes. Consequently, all structural members were within the scope of elastic performances under the actions of frequent earthquakes. The maximum displacements and storey drifts satisfied the requirements of the design codes within the scope of elastic or elastic–plastic deformations. The induced damages could reach “moderate damage” states, satisfying the requirements for the expected performances by the codes. The consequences indicated that the design scheme and critical parameters for the building structure satisfied the requirements of seismic performances from the codes.

Shape-memory alloy-friction isolator enhanced with inertia pendulum for seismic mitigation of bridges

Research has demonstrated that shape-memory alloy-based friction bearings (SMAFBIs) can obtain significant seismic response reduction and self-centering performance of isolated bridges. However, SMAFBIs, similar to conventional isolation techniques, reduce seismic forces at the cost of increasing deck drift. Excessive deck drift will increase the probability of the deck unseating, while large seismic forces such as base shear of piers will increase the risk of damage to piers. To limit the deck drift and the pier base shear of bridges isolated with SMAFBIs at the same time, an inertia pendulum (IP), which can amplify the inertia of a pendulum mass by a lever to effectively tune the natural period of structures, is proposed to enhance the bridge isolated with SMAFBIs. The seismic design spectrum of the linearized SDOF system with IP is proposed and examined by direct integration method. Based on this seismic design spectrum, the performance-based seismic design procedure for bridges isolated with IP-SMAFBIs is proposed. The two bridges isolated, respectively, with SMAFBIs and IP-SMAFBIs are designed according to this procedure, and their seismic responses obtained by elastic–plastic time history analysis are examined and compared. The research results show that IP-SMAFBIs have significant advantages in terms of reducing maximum deck drift not at the cost of increasing the pier base shear. In addition, the effects of the mass ratio and leverage ratio of the IP on seismic performance of the isolated bridge are investigated in detail, and the optimal parameters are suggested.

Rapid Seismic Evaluation of Continuous Girder Bridges with Localized Plastic Hinges.

In seismic assessment of continuous girder bridges, plastic hinges form in bridge piers to dissipate seismic energy through nonlinear restoring forces. Considering temporal and spatial variations of ground motions, seismic evaluation of the bridges involves nonlinear stochastic vibration and expensive computation. This paper presents an approach to significantly increase the efficiency of seismic evaluation for continuous girder bridges with plastic hinges. The proposed approach converts nonlinear motion equations into quasi-linear state equations, solves the equations using an explicit time-domain dimension-reduced iterative method, and incorporates a stochastic sampling method to statistically analyze the seismic response of bridges under earthquake excitation. Taking a 3 × 30 m continuous girder bridge as an example, fiber beam-column elements are used to simulate the elastic–plastic components of the continuous girder bridge, and the elastic–plastic time history analysis of the continuous girder bridge under non-uniform seismic excitation is carried out. Results show that the computation time is only 5% of the time of the nonlinear time history approach while retaining the accuracy. This study advances the capability of rapid seismic assessment and design for bridges with localized nonlinear behaviors such as plastic hinges.

Restoring force model of steel‐recycled concrete composite frame with infilled recycled block wall

SummaryTo study the restoring force model of steel‐recycled concrete composite frame with infilled recycled block wall, the experimental results of two recycled concrete‐filled steel tube frames with infilled recycled block walls and three steel‐reinforced recycled concrete frames with infilled recycled block walls under low cyclic loading were analyzed. The four broken‐line skeleton curve model which was suitable for this kind of composite frame was proposed, and the calculation methods for different stages of the skeleton curve were given respectively. According to the hysteretic characteristics of different frame specimens, the hysteretic loops for steel‐recycled concrete composite frame with infilled recycled block wall were simplified by using the treat methods of positive and negative symmetry and sudden drop of bearing capacity, and the restoring force model for different type of steel‐recycled concrete composite frame with infilled recycled block wall was established. At the same time, combing the experimental results, the proposed restoring force model was verified. The results show that the established restoring force model can predict the hysteretic behavior of steel‐recycled concrete composite frame with infilled recycled block wall well, and it can provide theoretical support for the elastic–plastic time history analysis of this kind of frame structures under earthquake.

A novel lever-based-inerter-enhanced self-centering damping system to retrofit double-column bridge bent

Research has demonstrated that the self-centering dampers (SCDs) can mitigate the maximum and residual displacement of multi-column bridge bents under seismic excitation. Application of SCDs also increases the stiffness of bridge bents, which could intensify other seismic responses, such as base shear and acceleration. In order to alleviate the increments of these responses, a novel inerter-enhanced self-centering damping system (ISCDS) is proposed by adding a lever-based inerter (LBI) to the shape-memory alloy-based SCD in parallel. The displacement design spectrum, including the effect of the inerter, is developed based on an existing design acceleration spectrum. Two double-column bridge bents retrofitted with ISCDS and SCD are then designed by direct displacement-based design (DDBD) method, and their seismic performance is examined and compared by elastic-plastic time history analysis. The results show the bridge bent retrofitted with ISCDS has obvious advantages in terms of reducing the use of self-centering material, maximum acceleration and maximum base shear compared to bridge bent with SCD under the premise of the similar control performance of maximum and residual displacement. Finally, the effects of the inertance-mass-ratio and amplification factor on the seismic performances of the retrofitted bridge are investigated, and the reasonable values of the two parameters are suggested.