Horizontal Low Cyclic Loading Research Articles

Seismic performance of frame with middle partially encased composite brace and steel-hollow core partially encased composite spliced frame beam

Steel-hollow core partially encased composite spliced frame beam (SHSFB) and middle partially encased composite brace (MPECB) demonstrate the potential to economize on steel consumption while exhibiting superior performance. To investigate the seismic performance of frames with SHSFBs and MPECBs, horizontal low-cyclic loading tests were conducted on four frame specimens, involving two two-story frames with no brace and two multi-story X-braced frames. Numerical simulations were performed using the “Open System for Earthquake Engineering Simulation” (OpenSees). The results indicate that the novel composite frames exhibit commendable seismic performance and energy dissipation capacity. The unbraced frame with SHSFBs has deformation capacity and mechanical properties comparable to bare steel frame. In contrast to the frame specimen equipped with bare steel braces featuring a 6mm flange thickness, the specimen utilizing MPECBs with 4mm flange thickness exhibits only a slight reduction of 3.60% in maximum bearing capacity and 2.68% in initial lateral stiffness. Significantly, each SHSFB and MPECB component reduces steel consumption by 16.71% and 24.79%, respectively, compared to bare steel components. Therefore, while ensuring adequate mechanical properties, frame structures equipped with SHSFBs and MPECBs will require less steel. Based on both experimental and simulation results, the formulas for predicting the ultimate bearing capacity and initial lateral stiffness of the novel composite frame were proposed, and the structural design for the multi-story X-braced frame was analyzed, offering valuable insights for practical engineering applications.

Experimental study on GFRP-steel double-skin rubber concrete composite piers under mixed loading

To address the issues related to the insufficient compressive and shear strength of rubberized concrete and to enhance the deformation capacity and longevity of composite piers, a novel approach involving the confinement of rubberized concrete with glass fiber-reinforced polymer (GFRP) tube and steel tube has been proposed. This method aims to create a GFRP-steel double-skin rubberized concrete composite pier. Pseudo-dynamic and quasi-static tests were conducted on the composite pier to assess its seismic response and residual seismic performance. The study investigated the failure mode, hysteretic characteristics, ductility, energy dissipation, stiffness, and self-centering capability of composite piers. Additionally, a correction coefficient for the equivalent plastic hinge length was proposed. The results indicate that the specimen maintains its elastic state when subjected to frequent seismic events. However, when subjected to infrequent seismic events, the glass fiber layer may fracture, leading to the development of white stripes, while the steel tube experiences yielding, transitioning into a plastic state. The shock absorption and toughness of rubberized concrete were effectively utilized when subjected to horizontal low cyclic loading, thereby mitigating the appearance of more pronounced damage in seismic-damaged specimens. The hysteretic curve was complete, demonstrating a significant energy dissipation capacity. This confirmation indicates that the composite pier can be a viable solution for sea-crossing bridges and complex environments.

Experimental and analytical study on steel-concrete-ECC composite frames with URSP-S connectors

To improve the slab crack resistance in the hogging moment region of steel-concrete composite frames, this paper proposes using Engineered Cementitious Composite (ECC) and Uplift-Restricted and Slip-Permitted Screw-type (URSP-S) connectors near the columns of the frames, the structural behavior of the innovative steel-concrete-ECC composite frames were experimentally and numerically investigated. Firstly, five 1/2-scaled steel-concrete composite frames were experimentally studied under vertical uniform slab loading and horizontal low cyclic loading. The failure mode and cracking, load-displacement relationship, stiffness and strength degradation, energy dissipating, and strain of composite frames with ECC and URSP-S connectors were analyzed, and good cooperative behavior and overall seismic performance were found. Then, it was compared with the results of the other four specimens with different slab materials and shear connector types. The experimental results showed that the use of ECC and URSP-S connectors improved slab crack resistance 55% in terms of crack width, and rarely influenced the structural performance of the composite frames. ECC played a major role in controlling the crack width while URSP-S connector played a major role in controlling the crack number. In addition, based on the test specimen with ECC and URSP-S connectors, an elaborate finite element (FE) model was developed and validated by the test results in terms of cyclic curves and failure mode. Moreover, supplementary modeling analyses with various parameters on the influence of the frame capacity were performed, where steel beam height was the most influential parameter.

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

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

Experimental study on the seismic performance of steel frames with infill ALC wall panels

To explore the seismic performance of H-shaped steel frames with infill precast autoclaved lightweight concrete (ALC) wall panels, the horizontal low-cyclic loading tests were conducted under vertical load. The influence of the connector style, the arrangement, and the integrity of the wall panels on the seismic performance of the structure were analyzed depending on four specimens of H-shaped steel frames with ALC wall panels and one hollow H-shaped steel frame. The failure mode, bearing capacity, rigidity and strength degradation, and energy dissipation performance were compared and discussed. The results showed that the steel frame with infill wall panels had better ductility and energy-dissipating capacity than the hollow frame. The infill ALC wall panels greatly enhanced the seismic performance of the frames and had a significant influence on the bearing capacity, stiffness, energy dissipation capacity, and ductility performance of the specimens. The maximum ductility factors and total energy dissipation of the steel frame with ordinary infill wall panels were 1.58 times and 2.27 times larger than those of the hollow frame. Due to cooperation with the steel frame, the panels delayed the buckling and in-plane deformation of the frame. The sliding connector improved the bearing capacity, displacement ductility, and energy dissipation of the overall structure compared with the hooking connector. Moreover, the bearing capacity of the frames with the reinforced wall panels was improved further. Additionally, the equivalent compression bar model was developed to estimate the bearing capacity of the steel frames with the infill ALC wall panels. The experimental conclusions and the proposed analytical model improve the practical design of the steel frames with the infill ALC wall panels in high-rise buildings.

Analysis of the Seismic Behavior of a Wall Pier of a Covered Bridge Based on the Multi-Layer Shell Element

To investigate the seismic behavior of the wall pier of a covered bridge, the multi-layer shell element in OpenSEES was used to carry out the numerical analysis under a horizontal low cyclic loading in the weak axis direction. The effects of the mesh divisions of the wall pier models were evaluated and the hysteretic curves, skeleton curves, bearing and energy dissipation capacity, stiffness degradation and displacement ductility of the wall pier with different lateral loading modes were mainly researched. The results demonstrate that the discretization of layers along the thickness direction of the multi-layer shell element model has a very limited effect on the hysteretic and skeleton curves. The mesh division of the horizontal direction depends on that of the vertical, and the vertical mesh spacing shall be longer than the plastic hinge with a length of 0.5744 m. The arrangement of the loading points is critical for the seismic behavior of the wall pier. The pier suffering the force from the five points presents a relatively strong energy dissipation and larger ductility, but this layout may cause a more concentrated force at the local position. When the loading points are evenly distributed, the capacity and displacement changes sharply and the ductility diminishes. Successively, the seismic performance indexes at the local position of the wall pier tend to be more consistent with the increasing loading points. The deformation and energy dissipation capacity of the nearby position with the denser side loading points becomes larger, but this has a minor impact on the seismic performance of the position far from the points. The wall pier without the bent cap and with three bearings set is supposed to be more reasonable for the covered bridge through the overall analysis of seismic performance.

Seismic Performance of Panel Connectors with Steel Frame Based on Autoclaved Lightweight Concrete (ALC)

This paper proposes new prefabricated autoclaved lightweight concrete (ALC) connectors which allow limited sliding. The seismic performance of the proposed connectors and a traditional connector (L-hooked bolt) were investigated in depth. Three specimens of full-scale steel frames with ALC panel and connectors were subjected to horizontal low-cyclic loading. The failure modes, hysteretic behavior, strength and deterioration of stiffness and energy-dissipating performance of all specimens were analyzed and discussed. The experimental results indicated that the frames of the new connectors were more reliable than the traditional connector. The energy-dissipating capacity of the specimen frames with new connectors increased by 23.0% and 24.4%, and deterioration of stiffness increased by 10.6% and 13.0%. The new ALC panel connectors not only increased elastic stiffness in the early stage, but also provided some stiffness in the elastoplastic and plastic stages. Using relevant construction measures, the frames with new connectors displayed good cooperative behavior and safety reliability. To summarize, the new ALC connectors tested showed excellent performance in resisting seismic loading and had good assembly efficiency and could provide a basis for the development and application of a new type of ALC steel frame connector.

Experimental and numerical study on the static and hysteretic behavior of a novel wood isolation device

This paper presents a novel wood isolation device able to reduce the whiplash effect of the wood-concrete hybrid structure under the earthquake. The device inherits the configuration of the ancient wood Dou-Gong by using some short wood components buckling each other, and makes use of sliding friction, rotary deformation of partial components and wood nonlinear deformation to dissipate energy. Both static and low-cyclic loading experiments as well as numerical simulations were performed to study the mechanical properties, hysteretic characteristics and energy dissipation capacity of the isolation device. The results indicate that the wood isolation device has sufficient vertical bearing capacity, stiffness, initial lateral stiffness and lateral deformation capacity. Under horizontal low-cyclic loading, its energy-dissipation is characterized by three stages, namely, initial deformation, horizontal sliding and post-sliding secondary deformation. Their hysteretic loops correspond to the reverse S-shape, parallelogram with sawtooth and full Z-shape, respectively. This observation indicates that the isolation device can consume some energy under frequent earthquake, and has excellent energy-dissipation capacity when the sliding occurs. Based on the hysteretic loops, the four-piecewise line model is proposed to describe the skeleton curve and restoring force model of the isolation device. The wood isolation device proposed in this paper not only inherits the essence of the ancient Dou-Gong but also exhibits excellent isolation performance, and thus has a potential application in practical engineering.

Anti-Seismic Test Study on the Grid-Tube-Type Double Steel Plate and Infilled Concrete Composite Shear Wall

In this paper, three test models were cast about the grid -tube- type double steel plate and infilled concrete composite shear wall, the horizontal low cyclic loading test was carried out, and hysteresis curves and skeleton curves were got under different coaxial compression ratios. The results show that the new composite shear wall has many advantages, such as full hysteresis curve, high bearing capacity, high ductility and high energy dissipation capacity. Under the large displacement angle of 1/25 and cyclic loading of 80 times, the plastic hinge area still maintains the large stiffness and bearing capacity, which can effectively prevent the collapse of the structure under the action of a major earthquake. New composite shear wall has good seismic performance, which can realize the design requirements of high axial compression ratio, high ductility and thin thickness walls.

Restoring Force Model of an Energy-Dissipation Joint in Hybrid Frames: Simplified Skeleton Curve and Hysteretic Rules

In this paper, a restoring force model, composed of a trilinear skeleton curve and hysteretic rules, is proposed based on nine pseudostatic tests of the energy-dissipation joint under horizontal low cyclic loading. The critical points of the simplified skeleton curve are obtained via theoretical derivation and FE simulation. The hysteretic rules for the joints are simplified as a concave hexagon, where the parameters of the critical points are optimized by the genetic algorithm (GA). Using the established trilinear skeleton curve, three different working stages, i.e., elastic, hardening, and softening, were divided by the critical points and the moment stiffness of three stages can be calculated. The proposed hysteretic rules of each stage can reveal and explain the “pinching” in the cyclic loading, which make it easier to understand the mechanism of the energy-dissipation joint. The comparison between the restoring force model and the tests shows that the simplified skeleton curves, the established hysteretic rules, and the ductility and the damping ratio are consistent with the experimental results. Finally, the effectiveness of the established restoring force model is verified.

Experimental Study on Seismic Behavior of Steel Frames with Infilled Recycled Aggregate Concrete Shear Walls

Experiments were performed on four specimens of steel frames with infilled recycled aggregate concrete shear walls (SFIRACSWs), one specimen of infilled ordinary concrete wall, and one pure-steel frame were conducted under horizontal low cyclic loading. The influence of the composite forms of steel frames and RACSWs (namely, infilled cast-in-place and infilled prefabricated) on the failure modes, transfer mechanisms of lateral force, bearing capacity, and ductility of SFIRACSWs is discussed, and the concrete type and connecting stiffness of beam–column joints (BCJs) are also considered. Test results showed that infilled RACSWs can increase the bearing capacity and lateral stiffness of SFIRACSWs. The connecting stiffness of BCJs slightly influences the seismic behavior of SFIRACSWs. In the infilled cast-in-place RACSWs, the wall cracks mainly extended along the diagonal direction. The bearing capacity was 2.4 times higher than in the pure steel frame, the initial stiffness was 4.3 times higher, and the displacement ductility factors were 2.44–2.69 times higher. In the infilled prefabricated RACSWs, the wall cracks mainly extended along the connection between the embedded T-shape connectors and walls before finally connecting along the horizontal direction. Moreover, shear failure occurred in the specimens. The bearing capacity was 1.44 times higher than that of the pure steel frame, the initial stiffness was 2.8 times higher, and the displacement ductility factors were 3.32–3.40 times higher. The degradation coefficients of the bearing capacity were more than 0.85, indicating that the specimens demonstrated a high safety reserve.

Seismic tests and numerical investigation of blind-bolted moment CFST frames infilled with thin-walled SPSWs

This paper aims to investigate the seismic response of blind-bolted moment concrete-filled steel tubular (CFST) frames infilled with thin-walled steel plate shear walls (SPSWs). Tests of two-storey blind-bolted circular or square CFST frames with thin-walled SPSWs subjected to horizontal low-cyclic loading were performed. Macroscopic finite element (FE) models of the specimens were primarily established by fibre beam-column elements, zero-length springs, and truss elements. The numerical simulation results were verified by the experimental data. A parametric analysis was conducted to analyse the influence of the axial load level, material strength, and height-thickness ratio of the steel plate etc. on the hysteresis behaviour and energy dissipation of blind-bolted moment CFST frames with thin-walled SPSWs. In addition, the mechanics of the semi-rigid frame with SPSWs were compared with the pinned and rigid frames with SPSWs using mechanical analysis model and FE model. The experimental and analytical results show that the blind-bolted moment CFST frames with SPSWs connected to the beams only exhibit preferable hysteretic response, ductility and energy dissipation. The peak strength, initial stiffness and energy dissipation of blind-bolted moment CFST frames infilled with thin-walled SPSWs can be significantly affected by the axial load level as well as the steel plates' yield strength, height-thickness ratio, aspect ratio, and connection type.

Study on seismic behavior of steel frame with external hanging concrete walls containing recycled aggregates

The suitability of precast concrete walls containing recycled aggregates as the enclosure system of steel structure was investigated. The experiment on steel frame with external hanging concrete walls containing recycled aggregates (SFECW) was carried out under horizontal low-cyclic loading, and the influence of beam-column joints forms on the SFECW was considered. The failure modes, structural capacity, lateral stiffness, ductility and energy dissipation capacity were analyzed. The experimental results show that the external walls can remarkably increase the structural capacity, stiffness and energy dissipation capacity, and the connecting stiffness of beam-column joints has negligible effect. There were obvious buckling deformation of the steel column base and serious cracking and damage of the wall at the hanging points, and the corresponding suggested improvements were proposed. Furthermore, the load-displacement curves and failure modes of the SFECW were investigated by the finite element method, and the influence of key parameters such as the position of hanging points, the strength grade of recycled concrete, the thickness of wall, the height-span ratio and axial compression ratio on the SFECW were discussed. The FEA results indicate that the design parameters associated with the external wall are less affected to hysteresis performance of the SFECW, which provides scientific basis for the design and practical application of the SFECW.

Cyclic testing of square CFST frames with ALC panel or block walls

An experimental program was conducted to investigate seismic behavior and failure modes of square concrete-filled steel tube (CFST) frames with autoclaved lightweight aerated concrete (ALC) walls. Four specimens of square CFST frames with ALC panel or block walls and one pure specimen of square CFST frame were carried out under vertical axial loading and horizontal low-cyclic loading. The connector type, the wall connection type, the wall type and the wall thickness were considered. The failure modes, hysteretic behavior, strength and rigidity degradation, ductility and energy-dissipating performance of all specimens were analyzed and discussed. The experimental results indicated that this typed square CFST frames with ALC walls exhibited good ductility and hysteretic energy-dissipating capacity. The embedded ALC walls greatly improved the rigidity and strength of square CFST frame compared with the external ALC walls. By reasonable construction measures and reliable connectors, such as hooked bolt, rocking connector, U-typed connector and angle steel, the square CFST frame with ALC walls displayed good cooperative behavior and safety reliability. They can be applied in high-rise composite structure buildings.

Seismic experiment and analysis of rectangular bottom strengthened steel-concrete composite columns

In order to study the working mechanism of rectangular steel-concrete composite columns subjected to compression-bending load and further determine the seismic performance index, a bottom strengthened rectangular steel reinforced concrete (SRC) column with concealed steel plates and a bottom strengthened rectangular concrete filled steel tube (CFST) columns were proposed. Six column models with different configurations were tested under horizontal low cyclic loading. Based on the experiments, the load-bearing capacity, stiffness and degradation process, ductility, hysteretic energy dissipation capacity, and failure characteristics of the models were analyzed. The loadbearing capacity calculation formulas for a normal section and an oblique section of bottom strengthened rectangular steel-concrete composite columns were pesented and a finite element (FE) numerical simulation of the classical specimens was performed. The study shows that the load-bearing capacity, ductility, and seismic energy dissipation capacity of the bottom strengthened rectangular steel-concrete composite columns are significantly improved compared to the conventional rectangular steel-concrete composite columns and the results obtained from the calculation and the FE numerical simulation are in good agreement with those from the experiments. The rectangular steel-concrete composite column with bottom strengthened shows better seismic behavior and higher energy dissipation capacity under suitable constructional requirements and it can be applied to the structure design of highrise buildings.

Experimental and numerical investigation on frame structure composed of steel reinforced concrete beam and angle-steel concrete column under dynamic loading

This paper describes experimental and numerical investigations on two specimens of frames composed of steel reinforced concrete beam and angle-steel concrete column under horizontal low cyclic loading. Based on the test results, the relationship curves of the horizontal load-displacement and the failure modes are acquired. Meanwhile the hysteretic behaviors, skeleton curves, stiffness degradation, energy dissipation, residential deformation of the two specimens are studied. Nonlinear structural analysis program OpenSEES is employed to predict the experimental curves. Using the verified numerical model, the influences of slenderness ratio, axial compression ratio, steel ratio of column, cross-section moment resistance of I-shaped steel in beam, ratio of longitudinal rebars of beam and prestressing level on skeleton curves are investigated. The results indicated that the two specimens exhibited the favorable ductility and energy dissipation capacity, and the beam depth could be reduced to improve service function because of the application of the prestress. The ultimate horizontal load decreases with the increase of column slenderness ratio, and firstly increases then decreases with the increase of axial compression ratio. In the meantime, the descent segment of skeleton curve is smooth with the increase of column slenderness ratio, and becomes steeper with the increase of axial compression ratio.

Experimental and Simulation Studies on the Seismic Performance of I-section Steel-Concrete Composite Columns

This study analyses the working mechanism and seismic performance index of I-section steel-reinforced concrete columns with concealed double steel plates and bottom-strengthened I-section concrete-filled steel tube columns subjected to compression-bending load. For this purpose, six column models with different constructions were tested under horizontal low cyclic loading. Based on the experiments, the load-bearing capacity, stiffness and degradation process, ductility, hysteretic energy dissipation capacity and failure characteristics of the models were analysed. The formulae for calculating the load-bearing capacity for the normal and oblique sections of I-section steel-concrete composite columns were derived, and the finite element (FE) numerical simulation of the classical specimens was performed. According to the results, the load-bearing capacity, ductility and seismic energy dissipation capacity of the bottom-strengthened I-section steel-concrete composite columns are obviously improved when compared with those of the conventional I-section steel-concrete composite columns. Moreover, the calculated and FE numerical simulation results are found to be in good agreement with the experimental results. Further, the bottom-strengthened I-section steel-concrete composite column shows better seismic behaviour and higher energy dissipation capacity under suitable constructional requirements, indicating their suitability for constructing high-rise buildings.

Experimental Research on the Seismic Behavior of Enclosing Masonry Walls Simulated the Structure of an Ancient Masonry Pagoda Strengthened with Steel Straps

in this paper, four single-layer masonry wall models in1/8 scale were made by a kind of special bricks on the basis of an ancient masonry pagoda structure. The models are divided into two groups by whether there is a masonry floor in a model or not. Pseudo-static test is introduced to study the seismic performance of four models with a special load control process which is suited to masonry structure. According to the test results, the horizontal bearing capacity and ductility of each masonry walls reinforced with steel straps under horizontal low cyclic loading has been sorted out. Four nonlinear restoring force models are inferred from the experimental results and phenomena under various operating conditions. And the shear capacity calculation formula of reinforced masonry wall models is fit out. The theory and experimental study show that seismic performance of the masonry pagodas strengthened with steel straps has been improved significantly.

Finite Element Analysis on the Resistance Capability of a New Precast Concrete Tube Column

A new type of composite structure, precast concrete tube column is proposed, and its axial compression performance and the seismic performance of beam-column joint are studied. Nine groups of precast concrete tube column models and three groups of common solid column contrast models with the same outer diameters (600,800,1000mm) were established by software ABAQUS, and a beam-column joint model for horizontal low cyclic loading was established combining with practical project. The results show that the ultimate bearing capacity of precast concrete tube column is higher than that of the common solid column with the same outer diameter by 5% to 20%, and it increases slightly as the thickness of tube increases. Displacement - load hysteresis curve of the beam-column joint is relatively full under cyclic load, and the slope of skeleton curve decreases slowly, which provides an important basis for engineering applications.

Finite Element Analysis on Circular Steel Tube Composite Column Filled with Steel Reinforced Concrete

The article analysis the seismic behaviors of circular steel tube composite column filled with steel reinforced concrete by the large finite element analysis software ABAQUS, adopted the load-displacement method and aimed at studying the mechanical properties of circular steel tube composite columns filled with steel reinforced concrete under horizontal low-cyclic loading, considering the degree of ductility, capacity of energy dissipation by the steel ratio and axial compression ratio. Under different axial compression ratios and steel ratios, the hysteresis curves and skeleton curves are carried out. Along with the increase of steel ratio, the deformation ability and ultimate bearing capacity are raised, but with the increase of axial compression ratio, the deformation ability becomes worse.