Cyclic Lateral Load Tests Research Articles

DEM study on the development of the earth pressure of granular materials subjected to lateral cyclic loading

The discrete element method (DEM) is adopted to study the development of the lateral earth pressure of granular materials subjected to lateral strain-controlled cyclic loading, which is imposed by integral abutments due to temperature variation. Clumped particles are used to simulate the nonspherical granular particles. The simulation results show that there is continuing buildup of lateral stresses with cycling for both loose and dense samples, while the loose sample experiences a substantial decrease in volume and the dense sample shows slight dilation. The simulated macro-response is qualitatively consistent with the laboratory observations. The micro-response is further investigated, and a unique relationship is revealed between the deviator stress ratio on the macro-scale and the deviator fabric of strong contacts on the micro-scale, which is not influenced by the initial porosity, vertical stress, or loading path. Although the cyclic lateral strain is small, a number of cycles can result in a certain micro-structure that can support large lateral stresses, which can also be achieved by lateral monotonic loading to large strains. The influence of the particle shape on the macro- and micro-responses of an assembly is highlighted by performing lateral cyclic loading test on a sample with spherical particles.

Seismic performance of precast concrete wall with vertical energy‐dissipating connection

SummaryA precast concrete wall with vertical energy‐dissipating connection (PCWVEC) was proposed in which X‐shaped metal dampers (XMD) with better energy‐dissipating capacity were installed along the vertical connections between precast wall panels, and the pore‐forming grouted lap‐sliced connector was adopted for the longitudinal steel bars between wall panels and floors. Lateral cyclic loading tests were carried out on two full‐scale specimens, including an assembled monolithic concrete wall (PCWVEC1) and unbonded post‐tensioning (PT) concrete wall (PCWVEC2), where the longitudinal steel bars at wall toes were replaced by PT tendons to provide the self‐centering capacity and bearing capacity. The seismic behavior of PCWVEC was experimentally investigated including failure mode, wall panel and XMD deformation, bearing capacity, ductility, strain, and energy‐dissipating capacity. The test results showed that XMDs used as vertical connection can effectively transfer the internal force and dissipate energy well. The average peak load of specimen PCWVEC2 was smaller than that of specimen PCWVEC1 about 13.67%. In addition, the finite element analysis (FEA) model of specimen PCWVEC2 was established, and the FEA results match well with the test results. Based on a parameter study, specimen PCWVEC2 with proper design parameter can have the same strength, energy‐dissipating capacity, and better self‐centering capacity.

Monotonic and cyclic lateral load tests on monopod winged caisson foundations in sand

Existing caisson foundations, utilised for offshore wind turbines, are required to resist significant lateral loads and overturning moments generated by wind and currents. This paper presents an innovative type of foundation, a ‘winged caisson foundation’, to support offshore wind turbines, which has the ability to provide a larger overturning capacity compared with standard caisson designs. Through a series of small-scale experiments at 1g conditions, the competence of the proposed foundations was examined. Different models with various wing sizes and different soil densities were tested in the laboratory under overturning loadings and the results were compared with a standard caisson. The moment–rotation performance of the foundation under both monotonic and cyclic loading was examined to assess the potential benefits of adding wings to caisson foundations. The results showed that there is a significant increase (up to 75%) in overturning capacity provided by the novel foundation, demonstrating its great potential over standard caissons for use in offshore wind turbine foundations.

Effects of cross-section shape on cyclic lateral response of steel piles in residual soil

The lateral cyclic loaded piles' behaviour in bonded residual soil is still poorly understood by classical geotechnics. Currently used models reproduce the behaviour of residual soils based on those from other unstructured soils, resulting in a conservative design. This paper thus proposes to evaluate the behaviour of three different shapes of steel piles embedded in bonded residual soil when submitted to cyclic lateral loading tests. These tests encompassed 10 mm displacements performed on the top of the piles (considering service (working) displacements). The piles, with a length of 2·0 m, were equipped with strain gauges at ten levels. The evaluated cross-sections have circular, square and H shapes, all with similar inertia moment and diameter/edge of 0·15 m. The effect of cyclic loading has shown a degradation of available lateral load, mostly in the first 30 cycles. This degradation is also seen at the bending moments obtained. The piles have also shown a short free-headed behaviour that rotates from a certain depth. Finally, the study showed that the square cross-section-shaped pile had the best performance under service (working) cyclic displacements when embedded in bonded residual soil, followed by H cross-sectioned pile and finally the circular cross-sectioned pile.

Seismic performance analysis of multi-span masonry infilled RC frame based on analytical strut model

According to previous studies, it was accepted that masonry infills have a contribution to lateral strength, stiffness, and ductility of reinforced concrete (RC) frames structures. In the past studies, an analytical method of diagonal strut model has developed for evaluating the seismic performance of masonry infill. In this model, the masonry infills were presented by compression struts as distributed forces at the frame-infill interfaces in which the frame-infill contact lengths were evaluated by static equilibrium related to compression balance and lateral displacement compatibility. The lateral strength of infill was determined based on frame-infill contact length. In the current study, an experimental study of quasi-static cyclic lateral loading tests was conducted to evaluate the seismic performance of two-bay brick masonry infilled RC frames. This paper discusses the results of seismic performance brick infills based on experimental and analysis results of the multi-span masonry RC frame applying the diagonal strut model. According to the analytical model, antisymmetric strut was acted at the top and bottom of the middle column of the multi-span infilled frame from each infill. As a result, good agreements of lateral strength of structures were obtained between the experimental and analytical values.

Experimental study of a three-storey concrete frame structure with smooth bars under cyclic lateral loading

Past lateral cyclic or seismic tests of concrete frames with smooth bars in columns are very few and limited as far as the test structure’s size and geometry are concerned; moreover, they have not focused on the effect of detailing and lap-splicing of such bars on local and global behaviour. To help fill this knowledge gap with new data, the paper presents the cyclic lateral load test of a 2:3-scale three-storey, one-by-two-bay, strong beam-weak column RC frame, focusing on the effects of the column’s smooth bars and of their detailing on local and global behaviour. Slippage of bars caused concentration of column deformations in flexural cracks at the top and base sections and gave to the global hysteresis loops a shape typical of bond-slip behaviour, but without cyclic strength decay. Despite chord rotation demands of up to 0.055 rads and storey drifts of almost 5%, damage was limited and had nothing to do with the use of smooth bars in the columns. Despite the important role of bar slippage for the response, bar strains show that wherever the surrounding concrete was in compression, column bars were in compression as well. Lap splices at and/or FRP wrapping of column end regions did not have systematic effects on column behaviour. Overall, no adverse effect of the use of smooth bars was identified.

Numerical and Experimental Investigation on Dynamic Characteristic Changes of Encased Steel Profile Before and After Cyclic Loading Tests

This paper presents a numerical and experimental investigation regarding changes in dynamic characteristics (natural frequencies, mode shapes, and damping ratios) of encased steel profile of concrete-encased composite column-steel beam connections prior to and following lateral cyclic loading tests. To do so, four specimens with different column-beam connection details were considered. Pre-ambient vibration measurements were first conducted to extract experimental dynamic characteristics of encased steel profile in column-beam connections using enhanced frequency domain decomposition (EFDD) method in frequency domain and stochastic subspace identification (SSI) method in time-domain. Next, encased steel columns were enforced with longitudinal rebar, stirrups, and concrete to turn them into concrete-encased composite column. Lateral cyclic loading tests were performed on composite column-beam connections until failure. Concrete, stirrups, and rebar were removed and cleaned from the encased steel column after the cyclic loading tests. Post-ambient vibration measurements were repeated on the damaged models for further evaluation and comparisons. Additionally, 3D finite-element models of the samples were constituted using Abaqus program, and modal analyses were performed for each specimen to obtain the numerical dynamic characteristics and compare them with experimental results. The results show that natural frequencies distinctly decrease due to damages in the column-beam connection zones. The maximum decreases were calculated as 8.53% and 16.01% in EPCSB-I; 6.92% and 16.44% in EPCSB-II; 17.38% and 12.20% in EPCSB-III; as well as 23.10% and 22.85% in EPCSB-IV for EFDD and SSI methods, respectively. Also, after the cyclic loading tests, increasing of flexibility and rotational movements due to the decrease in joint stiffness has affected the mode shapes. When the initial finite-element analyses and experimental results were compared with each other, the maximum differences were obtained between 0.18% and 8.99% for EPCSB-I, 2.62% and 25.27% for EPCSB-II, 0.84% and 28.60% for EPCSB-III, and 0.19% and 29.87% for EPCSB-IV, respectively.

Model Testing on the Effects of Section Geometry and Stiffness on the Cyclic Lateral Behavior of Piles in Loose Sand

In this study, two-way cyclic lateral loading tests with constant displacement amplitude are performed to investigate the effect of cross section geometry and modulus of elasticity on the behavior of model piles in sand. Various laboratory pile models were tested in a metal test tank equipped with various facilities including cyclic lateral loading system, devices to measure displacement and pressure along the pile, an inverter to adjust or change loading frequency, sand raining system, etc. Different cross section geometries, including square and circular shapes, were used for piles made of polyethylene and polyurethane. A loading frequency of 0.29 Hz and a total number of 145 loading cycles were used for all the tests. Results revealed that in constant displacement amplitude tests, both lateral load resistance of the pile head and stiffness of the pile–soil system increase with an increase in the number of loading cycles; however, the rate of increase gradually decreases. It is shown that these variations may be formulated using a logarithmic relationship, which includes a degradation parameter reflecting rate of these changes. For tests with different pile cross section shapes, dimensions, and moduli of elasticity, the degradation parameter varied from 0.08 to 0.18. The pile head load and stiffness of the pile–soil system at the end of the 145th cycle varied from 1.4 to 1.85 times those of the first cycle for different section shapes, dimensions, and moduli of elasticity.

Experimental study on seismic behaviour of composite frames with wide floor slabs considering the effect of floor loads

The steel–concrete composite frame systems are widely used in multistory and high-rise buildings owing to good mechanical performance and high construction efficiency. In previous research on the composite frame systems, many lateral cyclic tests were conducted on specimens with small-width floor slabs without floor loads, which could not precisely reflect the actual behaviour of composite frames in spatial multistory buildings. Therefore, this paper presents an experimental study on the seismic behaviour of composite frames with wide floor slabs considering the effect of floor loads. The specimen was a two-story two-span composite frame with the scale ratio of 0.5, and three load cases, including the vertical floor loading test, the lateral cyclic loading test and the pushover test, were respectively applied to investigate the mechanical performance of the composite frame. The slab crack development, mid-span deflection and strain distribution of slab reinforcements in the vertical floor loading test were discussed. The overall responses of the specimen in the lateral cyclic loading test and pushover test were analysed, including failure phenomena, load–displacement curves, strength and stiffness degradation, energy dissipation capacity and deformation characteristics. Moreover, the seismic performance of columns, beams, slabs and joints in the specimen was discussed in detail and the force mechanism of the composite frame was revealed based on the structural analysis of components. The results indicated that the specimen exhibited sufficient load-bearing capacity, good ductility, stable strength and stiffness degradation and excellent energy dissipation capacity under the combination of vertical floor loads and lateral loads. The welds at the bottom flange near the exterior joint fractured under cyclic loading, which was found to have significant influence on the deformation pattern and force mechanism of the composite frame. The shear lag effect was obvious in the wide floor slabs and the effective width of the slabs was estimated to be nearly 0.75 times the column width.

Structural capacity of reinforced concrete columns with U-shaped transverse bars

In large reinforced concrete (RC) columns for mega columns in high-rise buildings and plants, constructability is deteriorated due to difficulties in assembling long reinforcing bars. In the present study, U-shaped tie bars were studied to improve the constructability of large RC columns by replacing the hoops and cross ties with U-shaped tie bars. The compression loading test and cyclic lateral loading test were performed on RC columns to verify the effect of U-tie bars. For the test parameters, the types of U-tie bars, neutral axis depth of cross-section, and loading types were considered. The test results showed that the strength and deformation capacities of the columns using U-tie bars were comparable to those of the columns using conventional transverse reinforcement. Closely-spaced U-tie bars satisfactorily restrained early local buckling of the longitudinal bars and provided adequate confinement effect to the core concrete, without early failure of the U-bars. Further, design recommendations were discussed to use U-tie bars for transverse reinforcement in large columns.

Performance evaluation of recycled aggregate concrete-filled steel tubes under different loading conditions: Database analysis and modelling

This paper presents a set of data mining analyses on the structural performance of recycled aggregate concrete-filled steel tubes (RACFSTs) conducted using grey relational evaluation and Back-Propagation (BP) neural networks. A comprehensive experimental database containing the results of 20 flexural, 105 compressive and 85 lateral cyclic loading tests of RACFSTs manufactured using conventional recycled aggregates (RAs) (i.e., sieve grading varying from 5 mm to 31.5 mm) and demolished concrete lumps (i.e., sieve grading varying from 50 mm to 300 mm) were compiled through a critical literature review. The influential experimental variables identified through the review of the literature, namely the geometric ratios (i.e., steel tube diameter-to-wall thickness ratio and length-to-diameter ratio), steel tube strength grade, effective water-to-cement ratio, RA content and axial load ratio were selected as the input parameters to evaluate their influence on the structural performance (i.e., load carrying capacity, stiffness, peak strain, ductility and energy dissipation) of RACFST beams and columns. The results of the grey sensitivity analysis indicate that the effective water-to-cement ratio, steel tube strength grade, and steel tube diameter-to-wall thickness ratio and length-to-diameter ratio are in general the most influential set of parameters on the structural performance of RACFSTs, respectively; whereas, the overall performance of RACFSTs is less sensitivity to the RA content when compared with other parameters. It can also be seen from the results that the RA content influence on the seismic performance of RACFSTs is larger when conventional RAs are used in concrete mixes instead of demolished concrete lumps. To extend the parametric range of the experimental database, BP neural networks were employed to estimate the load carrying capacity of RACFSTs, and the results demonstrate that this machine learning algorithm can simulate the effect of RA content on the load carrying capacity of RACFSTs. Based on the extended database, two simple expressions were proposed to model the RA content influence on the axial and lateral load carrying capacities of RACFST columns.

An energy dissipating hold down device for cold-formed steel structures

A two-phase experimental investigation has been conducted for the development and evaluation of a hold down device that has energy dissipating feature. Focus of the first phase was the development of the device itself, while the second phase concentrated on the investigation of the performance of this device when used in a CFS framed sheathed wall panel that is subjected to reversed cyclic lateral loading. Hold down subassembly test results indicate that the load capacity of the hold downs is mostly limited by the shearing capacity of connection screws. Hold down devices themselves were observed to remain virtually undamaged under tensile loading, indicating a superior mechanical behavior in terms of strength and stiffness. As part of the second phase of the study, cyclic lateral load tests were conducted on seven CFS framed sheathed wall panels in order to study the energy dissipation ability of the proposed hold down device when used in CFS wall systems. Aligned with this focus, the anchor rods used to connect the hold downs to the foundation system in wall panel specimens were altered mainly by reducing the rod diameter within the middle portion over a certain length to provide controlled rod yielding under tensile forces. Controlled yielding of anchor rods was observed to reduce the drift demands imposed on wall panels due to seismic effects, resulting in a minimal damage on wall panels themselves.

Seismic performance of brick masonry infilled frame structures with bed joint reinforcements

This paper presents the evaluation of the seismic performance of brick infilled RC frame structures with bed joint reinforcements based on reversed cyclic lateral load tests. Three specimens of the structural model of 1/4 scale-down single-story single-bay brick infilled RC frame was prepared, which were brick infilled RC frames with and without bed joint reinforcements. Two specimens of brick infills with bed joint reinforcements were different in the spacing of bed joint rebars. The specimens were tested by applying a reversed cyclic lateral loading in-plane direction. During the tests, the crack propagation was observed at the peak and residual drifts of each loading cycle to recognize the failure mechanisms of the specimens. As the results, although the use of the bed joint reinforcements ineffective to increase the lateral strength of the overall infilled frame structure. The rebars in mortar bed joints role to sustain the lateral strength in plastic deformation, and provide the whole structure with high ductility. It seemed that the rebars in mortar bed joints confined the brick infills. Therefore, the infilled RC frames can survive in large deformation without failure of the infills in out of the plane direction.

Full-scale steel column tests under simulated horizontal and vertical earthquake loadings

This paper presents an experimental study to evaluate the vertical ground motion effects on steel wide-flange section columns in lower stories of steel frames. Eight full-scale specimens were tested utilizing the Multiple Usage Structural Testing (MUST) equipment, which can properly apply loading in both horizontal and vertical directions. Three cyclic lateral loading tests under constant axial load of 15% to 25% of nominal axial yield capacity were conducted to investigate the basic hysteretic behaviors. Five specimens were tested by pseudo-dynamic hybrid simulation with both horizontal and vertical excitations and an initial gravity load of 15% or 25% axial capacity. The failure mode of specimens tested by cyclic loading was notably influenced by the section compactness. Columns with thinner elements failed due to significant local buckling near the column ends corresponding to a drift ratio of 6% or even larger, while columns with thicker elements suffered rupture in the welding heat affected zones near column ends corresponding to a drift ratio of 4%. During the pseudo-dynamic hybrid loading with ground motions using the records of Imperial Valley earthquake and Northridge earthquake records, no rupture was observed. Lateral hysteretic response fluctuation was clearly observed in the pseudo-dynamic hybrid tests due to the inputs of both horizontal and the vertical ground motions. The pulse-type seismic input caused large residual displacements of the full-scale column specimens. Vertical ground motion also led to significant variations in axial loads, indicating the importance to study the seismic behavior of steel columns under realistic ground motion inputs.

Cyclic Loading Test of Structural Walls with Small Openings

This study aimed to investigate the effects of small openings on the structural performance of reinforced-concrete (RC) structural walls. Cyclic lateral loading tests were conducted on five RC walls with an aspect ratio of 2.6 and small openings. The main test parameter was the size of the small openings. The specimens were designed to fail after flexural yielding, considering the typical failure mode of slender RC walls. The structural performances of the test specimens were analyzed based on the test results in terms of the load-carrying capacity (flexural strength), hysteretic behavior, strain distribution, and the size of the openings. The specimens showed flexural yielding regardless of the size of the openings, and the flexural strength and deformation capacity were not significantly affected by the small openings. This result indicates that small openings do not affect the flexural behavior of slender walls if the walls have sufficient shear resistance and the small openings are located away from the extreme compressive end and in the compression zone where compressive stress does not decrease.

Cyclic Lateral Load Test for RC Column–Steel Beam Joints with Simplified Connection Details

AbstractExisting experimental results show that carefully designed RC column-to-steel beam (RCS) joints have high seismic resistance comparable to those of traditional steel or RC frames with seism...

Cyclic Behavior of a Bamboo-Steel Hybrid Moment Frame with a Novel Energy Dissipation Connection

This paper presents a novel bamboo/wood-steel hybrid frame which uses engineered bamboo products as beams and steel as columns. The beams and columns are jointed by an innovative connection which incorporates a steel hinge and two steel brackets to carry shear force and moment from the end of beam, respectively. The bracket consists of two segments, i.e. joint segment connected to beam and the other segment, which serves as energy dissipation panel (EDP), connected to the columns via a base panel. By this way, the connection can provide sufficient initial stiffness for serviceability requirements and excellent energy dissipation capacity for seismic performances. Lateral cyclic loading tests were conducted to investigate the seismic performances of the frame. It was found that hysteresis loops of the frame with energy dissipation joints show less pinching than that of frames with dowel- or bolt-type connections; by proper designing, the damage and failure of the frame can be restricted in the EDPs of connections, whereas virtually no damage was observed in the other components of the frame; the connection can provide more than 10 % damping for the frame after the yielding of EDPs. Design method is also proposed in this paper.

Cyclic p-y Curves of Monopiles in Dense Dry Sand Using Centrifuge Model Tests

In this study, centrifuge model tests were used to examine the lateral behavior of a monopile embedded in dry sand through cyclic lateral loading tests. The soil specimens used in the tests were dry Jumunjin sand with a relative density of 80% and a friction angle of 38°. A static loading test was performed once, and cyclic loading tests were performed four times using four magnitudes of cyclic load (30%, 50%, 80%, and 120% of static lateral capacity). The experimental cyclic p-y curve was obtained through the tests, and the maximum soil resistance points that were found for each load were used to find the cyclic p-y backbone curve for each depth. The two variables which are needed to define the cyclic p-y backbone curve, i.e., the initial modulus of subgrade reaction (kini) and ultimate soil resistance (pu), were suggested as functions of the soil’s physical properties and the pile. The cyclic p-y curve of the first cycle and the 100th cycle were formulated to present the upper limit and lower limit. The suggested cyclic p-y curve had an overestimated soil resistance compared with the existing API (1987) method, but the initial modulus of subgrade reaction was underestimated.

Cyclic lateral load test and finite element analysis of high-strength concrete-filled steel box columns under high axial compression

This paper presents an experimental study of the seismic performance of high-strength concrete-filled box columns (CFBCs) under combined axial and cyclic lateral loads. Specimens were made of high-strength SM 570 M steel (with yield strengths between 520 and 580 MPa), and concrete with compressive strength (fc') greater than 80 MPa. Three parameters that affect the seismic performance of CFBCs were investigated: the width-to-thickness (b/t) ratio of the steel column, magnitude of the axial load, and the addition of concrete infill. The specimens, which were 280–420 mm in width and 2000 mm in height, were tested under combined axial (4058–10,090 kN) and cyclic lateral loads. Experimental results indicated that the lateral displacement ductility decreases significantly with an increase in either the axial load or b/t ratio. The addition of concrete infill inside a hollow steel box column does not improve the lateral displacement ductility of CFBCs under high axial load. Although the CFBC specimens satisfied the b/t requirement of a highly ductile member, as per AISC Seismic Provisions (2016), specimens under high axial load (40%Pn) failed at 4% drift, indicating that the requirement does not guarantee that CFBCs will sustain high axial load under significant drift (i.e., >3%). The Eurocode 4 (2009), AISC Specification (2010), and Architectural Institute of Japan (2014) reasonably estimate the flexural strength of high-strength CFBCs under axial load; however, ACI 318 (2011) does not. The finite element analysis program ABAQUS can be used to estimate the hysteretic behavior of specimens before significant strength degradation.

Behaviour of Reinforced Concrete Frames with Central Opening Masonry Infill under Lateral Reversed Cyclic Loading.

This paper will describe the seismic behaviour of masonry infilled RC frame with a central opening structure under reversed cyclic lateral loading. To achieve the purpose of this study, four 1/4-scale single story and single bay RC frame specimens were tested, i.e. one bare frame, one clay brick masonry infilled RC frame without opening and two clay brick masonry infills with a central opening in infills. The ratios of opening size to panel area were 25% and 40%. Through reversed cyclic lateral loading tests, the seismic performance of RC frames with a central opening brick masonry infills was investigated. As the results, significant distinctions of failure mechanism, lateral strength, stiffness, and ductility were observed between these specimens. In the case of infills with a central opening, the cracks sprouted and developed at the corners of the opening. Although the presence of the opening in infill reduces the lateral strength and stiffness overall structure, the brick infilled frames with a central opening of 25% and 40% of panel area show better seismic performance as compared to the bare frame.