Cyclic Lateral Force Research Articles

Study of Capacity Calsium Board – Styrofoam Sandwich Panels on Wall Systems under Cyclic Lateral Force

Study of Capacity Calsium Board – Styrofoam Sandwich Panels on Wall Systems under Cyclic Lateral Force

Structural behavior of steel tube reinforced resilient RAC shear walls under static cyclic loading

This paper proposed a method to enhance the energy dissipation capacity of recycled aggregate concrete (RAC) shear walls reinforced with ultra-high strength bars (UHSB). The proposed method encases circular steel tubes within the boundary elements of walls. With the presence of steel tubes, steel fibers and axial load level as primary research variables, five RAC shear walls were fabricated and tested under reversed cyclic lateral force and constant axial compression to verify the effectiveness of the proposed method. The test results showed that the presence of steel tubes upgraded lateral resistance and enhanced energy dissipation capacity, while causing some subtle splitting cracks. Due to the yielding of the steel tubes, the encasement of the steel tube increased residual drift ratio at large drift, but the measured residual drift ratios of test walls still were kept less than 0.5 % until 2.5 % drift ratio. The addition of steel fibers delayed cracking, constrained the cover concrete and reduced damage to the specimens. Test results also indicated that increasing concrete strength and axial compression level could enhance the lateral resistance of the proposed wall. In addition, a numerical analytical method is presented to analyze the cyclic behavior of the proposed shear walls. Good agreement was observed between the measured and calculated hysteretic loops.

Seismic performance and analysis of resilient high-strength SRAC walls

This paper proposed a new type of resilient concrete wall consisting of steel fiber reinforced recycled aggregate concrete (SRAC) and weakly bonded ultra-high strength bars (UHSBs). Five specimens were fabricated and tested under reversed cyclic lateral force and constant axial load to investigate the seismic performance of the proposed resilient SRAC walls. Experimental parameters included the presence of steel fibers, the concrete strength, the volumetric ratio of the stirrup used in the boundary elements, and the axial load ratio. All test walls exhibited a stable increase of lateral resistance up to 2% drift ratio, while residual drift ratios were only about one-tenth of the transient drift ratios. Test results also indicated that adding steel fibers and increasing concrete strength could mitigate the development of cracks while increasing axial load could delay the development of UHSBs tensile strain and cracks. In addition, the residual drift ratios and corresponding design objectives, as recommended in FEMA 356 and previous studies, were introduced to evaluate the resilience of the proposed SRAC walls. All test specimens could meet the optimal performance design objective. Parallel to the experimental work, a method for simply calculating the skeleton curve and a model to evaluate the hysteretic loops of the proposed walls are presented. The calculated skeleton curves and hysteretic circles agreed well with the test results.

Seismic behavior of wall-type spiral stirrups-confined RC column to steel beam joint

This study proposes a new interior diaphragm joint between wall-type reinforced concrete column with high-strength spiral stirrups and steel beams, and the quasi-static test was conducted to investigate the seismic performance of the new joint under cyclic lateral force. Finite element model (FEM) simulation was carried out using the software ABAQUS, and the correctness of the FEM was verified by the results of the test. Additionally, the effect of parameters including the strength of concrete, thickness of the beam flange, interior diaphragm, joint flange, and joint web on the seismic performances of the joint was analyzed. Based on the parametric analysis and existing codes, a shear capacity formula was determined with the consideration of the shear capacity of the joint web and flange, and concrete. The comparison between the calculated and FEM results indicates that this formula could be regarded as an accurate calculation method for the shear-bearing capacity of different joint types in engineering design.

Cyclic behaviour and design of cold-formed round-ended concrete-filled steel tube columns

This paper presents a detailed investigation of the performance of cold-formed round-ended concrete-filled steel tubular (RECFT) columns under cyclic loading via experimental and numerical approaches. Experimental tests and observations of this type of novel composite column are presented, and its failure modes, hysteretic curves, ductility ratio, energy dissipation, stiffness, and strength degradation are revealed. A nonlinear finite element (FE) model of the RECFT column under cyclic loading is established and verified by the test results. Additional parametric analyses on the effect of material strength, axial compression ratio, diameter/thickness ratio, aspect ratio, and loading direction are subsequently performed using the validated FE methodology. Simplified prediction methods are proposed to assess the initial flexural stiffness, ultimate strength, ultimate displacement, and descending stiffness of the RECFT column under cyclic lateral force. The test and numerical investigation results indicate that the failure modes of the cold-formed RECFT column under cyclic loading mainly include concrete crushing, local buckling, and fracture of the steel tube. This type of composite column with a round-ended section exhibits good hysteretic behaviour, high ductility, and sufficient energy-dissipation capacity.

High-Velocity Shear and Soft Friction at the Nanometer Scale

We study high-speed friction on soft polymer materials by measuring the amplitude dependence of cyclic lateral forces on the atomic force microscope (AFM) tip as it slides on the surface with fixed contact force. The resulting dynamic force quadrature curves separate the elastic and viscous contributions to the lateral force, revealing a transition from stick-slip to free-sliding motion as the velocity increases. We explain force quadratures and describe how they are measured, and we show results for a variety of soft materials. The results differ substantially from the measurements on hard materials, showing hysteresis in the force quadrature curves that we attribute to the finite relaxation time of viscoelastic surface deformation.

Flexural behavior of curved steel-plate composite (SC) walls under combined axial compression and cyclic lateral force

The curved steel-plate composite (SC) walls, commonly used in nuclear power plants have not been adequately investigated. This paper aims at the curvature effects on the in-plane and out-of-plane flexural behavior of SC walls with consideration of axial compression. Eight specimens were tested under combined constant axial compression force and cyclic lateral force. The failure modes, moment-drift responses, ductility, stiffness degradation, ductility and energy dissipation are reported. Finite element (FE) models using ABAQUS were established and benchmarked with test results. Results show that the curvature effect on the structural behavior of curved SC wall is insignificant. For the flexural capacities of curved SC walls with T/R ratios no more than 0.5, negligible influential factors λ due to the curvature effect are seen. For the SC walls subjected to in-plane loading, −6.9% ≤ λIP ≤ 0.0% and when under out-of-plane loading, −6.9% ≤ λOP ≤ 6.0%. The plastic in-plane and out-of-plane flexural capacities of flat SC walls considering the axial compression were derived. To modify the proposed equations and determine their limitations, a parametric study was carried out in terms of the parameters including material grades of steel and concrete, reinforcement ratios, axial compression ratios.

Flexural-capability of angle-stiffened channel-type SC wall under combined cyclic lateral-force and axial-compression

Thanks to the proven efficiency in construction schedule and great resistance to seismic and impulsive loading, the steel-plate composite (SC) walls have been widely used. When serving in nuclear power plants, the SC wall could be required to have a large wall-thickness. In that case, the angle-stiffened channel-type connectors are more feasible to link the two steel plates of SC walls compared with tie-bar type or J-hook type connectors. The reason is that the angle-stiffened embedded-channel connectors could be of larger intervals to ease the welding and concrete vibration work, meanwhile, the angle-ribs could prevent the steel plates from buckling and provide additional flexural capacities. However, the in-plane and out-of-plane flexural capabilities of angle-stiffened channel-type SC wall under combined axial compression and cyclic lateral loading have not been adequately studied. This paper presents the development and validation of finite element models (FEMs) based on the former tests, where the flexural failure of angle-stiffened channel-type SC walls is obtained under combined axial compression and cyclic lateral loading. The validated FEMs are then used for an extensive parametric study to emphasize the influence of reinforcement ratio, axial compression ratio, sectional area and distance of angle ribs, aspect ratio (or height-to-thickness ratio) and material properties on the flexural capability of angle-stiffened channel-type SC wall considering axial compression. Based on the test and numerical results, the formulas for the in-plane and out-of-plane flexural capabilities of angle-stiffened channel-type SC wall are proposed by considering the effect of axial compression and angle ribs, respectively.

Seismic Performance and Confinement Reinforcement Design of High-Strength Concrete Columns Confined with High-Strength Stirrups

This paper aims at analyzing the failure process, failure modes, characteristics of hysteresis loop and the ductility of 10 high-strength concrete (HSC) columns confined by high-strength complex stirrups under cyclic lateral force and a higher constant axial loading. It is indicated that the hysteresis loop of this type of columns still show plump spindle-shaped at higher axial compression ratio, which shows better ductility, energy dissipation and anti-collapse performance. Therefore, it is an effective measure of setting high-strength stirrups to ensure the good ductility of HSC columns under high axial compression ratio and to increase the limit value of axial compression ratio. The stress of transverse reinforcement is evaluated, which shows that high-strength stirrups have yielded when most of the specimens are destroyed, and the strength of stirrups can be fully developed to provide a better effect of restraint. Based on a large number of experimental data, the relationships between the limit drift, the ductility coefficient of HSC columns and axial compression ratio, stirrup characteristic values, covering layer as well as longitudinal reinforcement ratio are established; the calculation formula of minimum stirrups characteristic value of HSC columns at different seismic levels considering of axial compression ratio is presented.

The effect of shear-moment interaction on the shear strength of confined masonry walls

It is hypothesized that the shear strength due to tension in confined masonry walls is caused by lateral deformation, regardless of the force that causes the deformation: shear, a moment or a combination of both. Based on this hypothesis, an a priori estimation formula for the shear strength is proposed. The proposed expression predicts a reduction in the shear strength when a moment is applied on top of the wall. The predictions of the proposed expression are compared with those of other formulas that include the shear-moment interaction. To verify the predictions, six full-scale confined masonry walls were subjected to a cyclic lateral force and a moment on top of the wall. The results indicate a decrease in the shear strength capacity of the walls when the moment is applied, and this decrease is consistent with the predictions. This reduction is more important for slender walls. The details of the experiments are provided, and the results are discussed.

Experimental study on steel-plate composite wall-to-foundation connections subjected to combined axial compression and cyclic lateral-force

Nowadays, great attention has been arisen on steel-plate composite (SC) walls, but studies on SC wall-to-foundation connections were rarely reported. In this paper, eight large-scale specimens were designed and tested to investigate the in-plane and out-of-plane behavior of SC wall-to-foundation connections subjected to combined axial compression and cyclic lateral-force. Test parameters mainly included the loading direction (in-plane and out-of-plane), construction detail of the connection (lap-splice and embedding) and the aspect ratios or height-to-thickness ratios of SC walls. The effects of test parameters on SC wall-to-foundation connection performance were discussed. For test specimens subjected to in-plane loading, results showed that the specimens all failed by flexure. For specimens subjected to out-of-plane loading, the specimens with the wall height-to-thickness ratio of 1.33 and 2.5 failed by shear and flexure-splitting, respectively. The lap-splice connection could be regarded as an over-strength connection since failure usually occurs on the connection while the embedding connection could be designed as a full-strength connection where the SC wall itself fails, according to AISC N690s1-15. The lap-splice connections had better ductility than embedding connections. The specimens with larger SC-wall aspect ratios or height-to-thickness ratios had better ductility. The current expressions for the in-plane and out-of-plane load-carrying capacities of SC walls were evaluated based on the test results. The comparison showed that the current expressions generally underestimated the load-carrying capacities of the specimens. Since both construction details of lap-splice and embedding had been proven feasible for practical use in SC wall-to-foundation connections, further studies on the design of both connection types were recommended.

Strengthening of Corroded RC Bridge Piers Subjected to Seismic Loads Using UHPFRC Jacketing

Corrosion of steel reinforcement is the main damage issue for the efficiency and performance of reinforced concrete (RC) bridge piers located in aggressive environments. In this study, the possibility of strengthening corroded RC bridge piers with high corrosion leveled by ultra-high performance fiber RC (UHPFRC) jacketing was investigated numerically. The model of nonlinear 3-D finite-element (FE) was constructed by using ANSYS software. The parameters of axial force ratio, longitudinal reinforcement ratio, aspect ratio, and transverse reinforcement ratio were studied to determine their effect on the lateral load resistance of strengthening corroded RC bridge piers. The verification carried out between the constructed FE and the experimental results of ten RC bridge piers in four experimental studies. The performance of RC bridge piers under cyclic lateral displacement and axial force was studied with different ratios. Finally, a practical model to calculate the lateral load resistance of corroded RC bridge piers was proposed. The results of this research suggest that this technique could be applied for existing concrete bridge exposed in the marine environment whereas, the concentration of corrosive chlorides are high and can also use for any shape of a column and this technique allows keeping the initial dimension of the column.

Reliability modeling of high-voltage power lines in a sharply continental climate

One of the important elements of the high-voltage transmission line is 110 kV, the damage of which leads to under-supply of electricity, i.e. reducing the reliability of the lines. Damage to the reinforcement from the applied load occurs due to material fatigue. The main causes of damage to the reinforcement are ambient temperatures and wind forces on this element. Periodic kinks of the wire are observed at the places of installation of the connecting and supporting clamps, vibration dampers, and cyclic lateral forces arise. The simultaneous impact of the above efforts leads to fatigue damage to the suspension systems. From the cyclic load, the nodes of rigid structures are destroyed, which bear the maximum load.

Experimental Investigation into the Seismic Performance of Fully Grouted Concrete Masonry Walls Using New Prestressing Technology

In recent years, traditional masonry structures have been widely used in rural areas of China. However, they were found to have a poor seismic performance during earthquakes. In this study, a new prestressing technology was proposed and described in detail, and it was used in fully grouted concrete masonry wall systems to improve its seismic performance. The experimental work involved investigating the seismic response of four fully grouted reinforced concrete masonry wall systems, consisting of two symmetrically arranged reinforced block masonry walls, with different section types and prestressing technologies, when subjected to cyclic lateral force. Based on the test results, a flexure and ductile failure occurred in the specimens with a rectangular section, while a shear and brittle failure occurred in the specimens with a T-shape section. The prestressing technology had no significant effect on the failure state of the specimens, but it influenced the crack propagation, making cracks fine and densely covered. A symmetrical and obvious pinching effect was observed in the hysteretic response of all specimens. The average displacement ductility of the specimens varied within a range of values between 3.34 and 6.92, according to the section type of the specimens, and the prestressing technology improved the displacement ductility of the specimens. Moreover, the prestressing technology significantly improved the initial stiffness of the specimens, and the specimens with prestressing technology experienced a greater fall in the degradation of the normalized stiffness than the specimens without this technology throughout the loading process. In addition, the equivalent viscous damping of the specimens ranged between 8.2% and 10.8%, according to the section type. It could be concluded that the prestressing technology improved the energy dissipation of the specimens at the ascending stage, although it had no marked influence on the equivalent damping ratio of the specimens.

Problems of operation of small-capacity automobile trailers in various fields of agriculture

The article discusses the prospects for the development and use of SRT (small-tonnage road trains) with a controlled coupling device developed and confirmed by the application (2018137360) of Volgograd State Technical University and Federal Scientific Agroengineering Center VIM. Small-tonnage road trains in terms of noise, ecology and fuel consumption are much superior to main-line trains when used in megacities, as well as in difficult road conditions. An increase in the number of small enterprises in recent years, including enterprises engaged in agriculture, maintenance of greenhouses, retail outlets, hunting and the provision of services in this area, increases the need for small trailers used in conjunction with automobiles. A controlled hitch allows eliminating «wobble», as well as providing the ability to steer in reverse. In various sectors of the national economic activity, SRT has advantages in servicing small enterprises, cooperatives, greenhouses and agricultural enterprises. Among other things, it does not require retraining of drivers and a quick payback time of less than 3 months. SRT is a universal type of transport. This is achieved by the development of various trailed platforms necessary to carry out various types of work. It can also be a trailed mini-plant for processing and recycling waste from agricultural enterprises (cowsheds, poultry farms, greenhouses, etc.). A possible option is a mini workshop, a kitchen, a mobile first-aid post for servicing workers engaged in sowing, cleaning, etc. In connection with new trends in the development of road transport, it is advisable to develop SRTs in an automated control option, through GLONASS using the Skif and Scout systems, as well as the trailer’s ability to independently move in geopolation mode for various tasks. With all the obvious advantages, there are negative phenomena that require thorough study and the possibility of eliminating these phenomena. Studies require the movement of a SRT with a high trailer when exposed to large or cyclic lateral forces, as well as the exclusion of wobble when moving along a longitudinal track and when overtaking.

Analytical modeling of reinforced concrete columns subjected to bidirectional shear

Under general seismic loading, reinforced concrete columns may be subjected to lateral loads in more than one direction. Available experimental data on columns subjected to bidirectional forces indicate that higher levels of damage and a higher loss of ductility and strength have been observed compared to similar tests under unidirectional shear forces. In this study, an experimental program was conducted in which six lightly reinforced concrete columns were subjected to unidirectional and bidirectional cyclic shear forces. This observation was used to identify the mechanisms and parameters governing the behavior of columns subjected to cyclic bidirectional lateral loads. Hence, a new conceptual model was developed to obtain the capacity of member. The shear forces were analyzed and an analytical formulation was derived to account for the effects in the concrete stress-strain relationship, the moment-curvature diagram and the plastic hinge length. These equations were used along with a structural model with concentrated plastic hinges to obtain the capacity curve of the column. The results of the formulations developed were verified using the results of the experiments performed on columns subjected to unidirectional and bidirectional cyclic lateral forces.

Influence of Structural Stiffness on Ratcheting Convection Cells of Granular Soil under Cyclic Lateral Loading

In granular soils, long-term cyclically loaded structures can lead to an accumulation of irreversible strain by forming closed convective cells in the upper layer of the bedding. The size of the convective cell, its formation and grain migration inside this closed volume have been studied with reference to different stiffness of the embedded structure and different maximum force amplitudes applied at the head of the structure.This relation was experimentally investigated by applying a cyclic lateral force to a scaled flexible vertical element embedded in a dry granular soil. The model was monitored with a camera in order to derive the displacement field by means of the PIV technique. Furthermore, the ratcheting convective cell was also simulated with DEM with the aim of extracting some micromechanical information. The main results regarded the different development, shape and size of the convection cell and the surface settlements.

Experimental study on steel reinforced high-strength concrete columns under cyclic lateral force and constant axial load

This paper presents the results of an experimental study on the seismic behavior of steel reinforced high-strength concrete (SRHC) columns. A total of 21 SRHC columns were tested under simulated earthquake loading conditions, and the major experimental parameters were the axial load level, stirrup arrangement, structural steel details and studs. The effects of these parameters on the behavior of the SRHC columns were analyzed in detail. The test results showed that SRHC columns with multiple stirrups and commonly used structural steel ratios demonstrated excellent seismic behavior and were suitable for use in high-rise buildings in seismic regions. The axial load had a negative effect on the energy dissipation and deformation capacity. Stirrups exhibited little effect on the initial stiffness and lateral force at cover spalling, but had a positive effect on the energy dissipation and deformation capacity. The benefit of structural steel was more obvious when the effective confinement index was larger or the SRHC columns were subjected to a greater axial load. Structural steel also improved the positive effect of the stirrups. It is suggested that multiple stirrups should be adopted in SRHC columns to provide full play to structural steel; in addition, more structural steel should be adopted when significant axial loads are applied to SRHC columns. Studs did not significantly affect the performance of SRHC columns during the early loading stage. However, columns with studs exhibited better energy dissipation and deformation capacity along with slower stiffness degradation.

Seismic retrofit of circular RC columns through using tensioned GFRP wires winding

The aim of this paper is to suggest a jacketing method using glass fiber reinforced polymer (GFRP) wires for reinforced concrete (RC) columns with lap splice of longitudinal reinforcement. For this study, four RC columns were prepared of 400 mm in diameter and 1400 mm in height with an aspect ratio of 3.5; two were lap spliced and the other two had continuous longitudinal reinforcement. One specimen of each of the two types was jacketed by GFRP wires that had a diameter of 1.0 mm. The GFRP wires were tensioned with small force during winding each column. The jacket comprised stepped layers along the variation of bending moment of the column. Cyclic lateral force was applied at the top of the columns, and the top displacement of the columns as well as corresponding force was measured during the bending tests.This study considered the failure of the four tested columns and analyzed their later force–displacement behavior. Additionally, the effective stiffnesses of the force–displacement curves were evaluated. The GFRP wire winding jacket prevented splitting of the lap-spliced reinforcement in the lap-spliced column and delayed buckling of the longitudinal reinforcement. The jacket protected the continuous reinforcement column against steel buckling and concrete spalling off and, thus, induced shear failure in the column. The GFRP wire winding jacket increased the failure drifts of both jacketed columns compared with those of the references.

Experimental investigation on the seismic performance of steel–polypropylene hybrid fiber reinforced concrete columns

Addition of fibers into cementitious composites has raised concern over decades, which enables considerable improvement in mechanical and dynamic properties of reinforced concrete (RC) members. In this paper, we present an experimental study on the seismic performance of steel–polypropylene hybrid fiber reinforced concrete (HFRC) columns, which is of vital significance to postearthquake serviceability of structures. A total of 24 specimens subjected to combined constant axial load and cyclic lateral force were investigated. The main variables involve fiber type, shear span ratio, axial compression ratio, and reinforcement ratio (longitudinal and transverse). The failure modes, ultimate bearing capacity and deformation capacity were analyzed. The experimental results showed that the presence of hybrid fibers in RC columns had positive influence on improving the seismic bearing capacity. The improvement ratio could reach to 15–20% when a relative high axial compression was applied. Moreover, in comparison to RC columns, HFRC columns exhibited a notable synergetic effect in terms of ductility and energy dissipation capacity, particularly for columns with a higher axial compression ratio. Subsequently, on the basis of principles of equilibrium and compatibility, analytical equations to estimate the seismic bending moment capacity and shearing force capacity were developed, which took into account the synergetic effect of hybrid fibers. The analytical solutions were then validated by the test results, and the correlations were observed in reasonable accuracy.