Lateral Load Tests Research Articles

Monotonic and cyclic lateral loading of piles in low- to medium-density chalk

Offshore and other structures often rely on driven piles to carry lateral loads. However, there is currently no established design method to cover lateral loading at chalk sites, which are widespread across Northwest Europe. This paper reports monotonic and cyclic lateral load tests on highly instrumented 508 mm and 1220 mm diameter. open steel piles driven at a well-characterised chalk test site in Kent, UK, for a recent joint industry project that developed new benchmark datasets and analyses, supported by high-quality testing. The ultimate lateral pressures mobilised in the chalk are shown to be relatively low compared to its uniaxial compressive strengths (UCS) due to pile-driving damage, natural fracturing, local yielding and brittleness. Significant gaps opened between the piles and chalk during loading, that led to a substantially softer response on unloading and subsequent reloading, as well as marked axial capacity losses. Reaction curves extracted from the field measurements and applied in a one-dimensional numerical model perform well in reproducing the monotonic lateral tests. As with piles driven in other materials, one-way cyclic lateral loading led to permanent displacement accumulation and stiffness changes that were linked to the cyclic loading parameters. Both effects were more marked under biaxial cyclic lateral loading.

Centrifuge Modelling of the Load-Deflection Response of Single Piles in Sand Under One-Way Cyclic Lateral Loads

This article aims to present the experimental results of one-way cyclic lateral loading tests on centrifuged small-scale models of piles in sand, carried out in the IFSTTAR centrifuge, center of Nantes (France). After a literature review, the pile models, their instrumentation, the experimental devices, as well as the construction of the sand mass were described. Cyclic P-Y lateral reaction curves were derived and the effect of the number of cycles, the soil density, the pile/soil interface roughness, as well as the pile/soil stiffness ratio on their parameters were analyzed. The experimental evolution of the pile top deflection as well as the bending moment along the pile were compared to the usual formulations of the cyclic degradation law.

Experimental study on the seismic performance of two-storey UHPC modular building structure

Ultra-high performance concrete modular building is a new structural system in which the module units made by the factory with UHPC materials are transported to the site for assembly. To study the seismic performance of UHPC module building structures, a two-story full-scale module building structure made by UHPC is designed in this study. Lateral cyclic loading tests are performed to investigate the seismic performance of the module building structures. The bearing capacity, failure mode, stiffness degradation, hysteretic performance, residual deformation, and strain skeleton curve are analyzed. Results indicate that the specimen undergoes three stress stages: elasticity, yield, and ultimate under lateral cyclic loading. At ultimate load capacity, the maximum inter-story drift ratio reached 1/57, and the load-bearing capacity was approximately 1.20 times the yield strength. The average ductility factor of the specimens was 3.42. The cracks mainly appear at the bottom and top of the walls of the module unit, and initial cracks occur at the top of the wall of the upper module unit. The specimen exhibits excellent seismic performance, full hysteretic curves, good dissipation capacity and ductility. The four corners between module units are connected by grouting sleeves in a reliable way to transfer force, which can ensure the overall deformation requirements of the structure.

Seismic performance of FRP-repaired RC piers after blast loading

Aiming to evaluate the effectiveness of fiber-reinforced polymer (FRP) repair on the seismic performance of blast-damaged reinforced concrete (RC) piers, the field test and numerical simulation were conducted. Firstly, a successive field explosion test, carbon FRP (CFRP) repair, and lateral cyclic loading test were performed on two 1/2-scale RC pier specimens. The test data including the incident overpressure-time histories of blast wave, damage profiles and lateral force-displacement relationships of pier specimens, etc. were comprehensively recorded and discussed. By comparing with the previous blast-damaged pier specimen, the negative maximum force and ductility of CFRP-repaired pier were increased by 97 % and 44.9 % after 1.0 kg TNT explosion, respectively. Then, an integrated numerical simulation approach based on explicit-implicit switching and full restart algorithms was proposed and validated in predicting the dynamic and quasi-static behaviors of RC piers under successive blast loading, CFRP repair, and lateral cyclic loading. Finally, a prototype RC pier was designed and the suicide vest bomb (TNT equivalence of 9 kg) specified by the Federal Emergency Management Agency was selected as the threat of contact explosion. The influences of FRP type, repair height, and number of FRP layer on restoring the seismic performance of the blast-damaged pier were further discussed. It indicates that, (i) CFRP is more effective than glass FRP and aramid FRP; (ii) increasing the repair height could not significantly improve the seismic performance of pier; (iii) the number of FRP layer has significant effect, e.g., the positive and negative maximum forces after 4-layer CFRP repair are improved by 9.4 % and 45.3 % compared to the unrepaired pier, respectively. The present study could provide a helpful reference for assessing the FRP repair effectiveness on the seismic performance of blast-damaged RC bridge piers.

In-Plane Cyclic Behaviour Comparison of Adobe Wall Retrofitted by Mortar Enhanced by Physical and Chemical Methods

ABSTRACT A mortar overlay on damaged adobe masonry is employed for its load carrying capacity improvement and low skill requirement. Nevertheless, delamination between the adobe wall and mortar has been commonly observed due to bonding failure. Physical enhancement (groove, shear dowel, and wire mesh) and chemical enhancement (a novel biological and traditional Chinese binder, sticky rice pulp, SRP) are carried out to enhance the bonding between mortar and adobe. The high-moisture adsorption mortar is also utilized to alleviate water accumulation resulting from the application of mortar on earthen buildings. Four adobe walls with different retrofitting methods are subjected to in-plane lateral cyclic loading tests to analyse the failure mode, hysteretic load-displacement response, skeleton curve, ductility behaviour, energy dissipation and stiffness degradation. It indicates that the retrofitting effectiveness of adobe walls coated only with mortars is limited, as their peak load increases are comparatively modest compared to other retrofit wall systems. However, employing additional bonding enhancement methods significantly enhances the peak load capacity. Specifically, a combination of physical and chemical enhancements results in a remarkable 114% increase on the positive side and an astonishing 500.1% increase on the negative side.

A Transparent Soil Experiment to Investigate the Influence of Arrangement and Connecting Beams on the Pile-Soil Interaction of Micropile Groups.

The use of a micropile group is an effective method for small and medium-sized slope management. However, there is limited research on the pile-soil interaction mechanism of micropile groups. Based on transparent soil and PIV technology, a test platform for the lateral load testing of slopes was constructed, and eight groups of transparent soil slope model experiments were performed. The changes in soil pressure and pile top displacement at the top of the piles during lateral loading were obtained. We scanned and photographed the slope, and obtained the deformation characteristics of the soil interior based on particle image velocimetry. A three-dimensional reconstruction program was developed to generate the displacement isosurface behind the pile. The impacts of various arrangement patterns and connecting beams on the deformation attributes and pile-soil interaction mechanism were explored, and the pile-soil interaction model of group piles was summarized. The results show that the front piles in a staggered arrangement bore more lateral thrust, and the distribution of soil pressure on each row of piles was more uniform. The connecting beams enhanced the overall stiffness of the pile group, reduced pile displacement, facilitated coordinated deformation of the pile group, and enhanced the anti-sliding effect of the pile-soil composite structure.

Seismic strategy of non-seismically designed reinforced concrete columns retrofitted with steel rods

This paper presents experimental results of combined cyclic load testing on a reinforced concrete (RC) column that was retrofitted with newly designed steel rods. The steel rods were installed around the column longitudinally and then anchored. The proposed steel rods utilize simple components and installation to enhance both the strength and ductility of RC columns. Cyclic lateral load tests were conducted on three specimens: one unreinforced specimen as reference, one specimen with the entire length of the column retrofitted, and one specimen with only the plastic hinge region of the column retrofitted. All specimens were tested under eccentric constant axial load and incrementally increasing lateral loading cycles with eccentricity. The implementation of steel rods resulted in significant improvement in ductility and an up to 60% increase in ultimate loading capacity.

Shear strength of steel-concrete composite walls (aspect ratio 2.0) with steel U-SECTION boundary element

A steel-concrete composite wall with steel U-section boundary elements was developed for enhanced structural performance and constructability. In the present study, cyclic lateral loading tests were performed to investigate the shear strength of the proposed walls. Test parameters were the type of boundary reinforcement (rebars or steel U-sections), sectional area of steel U-sections, and type (horizontal rebars, steel plate beams, or steel faceplates) and spacing of web reinforcement. The test results showed that the boundary steel U-sections restrained diagonal tension cracking and shear sliding in the web. Further, the steel U-sections restrained cracking and crushing of the boundary concrete, confining the boundary zone. For this reason, the shear strength of the composite wall was 35 % greater than that of the counterpart reinforced concrete wall with conventional boundary reinforcement. The use of steel plate beams and steel faceplates further increased shear strength. Existing reinforced concrete design methods underestimated the shear strength of the composite walls, neglecting the contribution of steel U-sections. The tested shear strengths exceeded the web crushing strengths of ACI 318, even though the horizontal web reinforcement ratio was less than the code-based maximum ratio.

Direct Field Curve Fitting Method to Determine Hardening Soil Parameter for Geotechnical Projects

Abstract In a wide archipelago country like Indonesia, transporting soil samples for laboratory tests are quite a bit of challenge in terms of cost and time as those need to be transported for weeks to nearest big cities. In-situ tests and correlation methods can be used as an alternative solution for preliminary or detailed design beside having on site laboratory. Correlating in-situ test results to hardening soil parameter (e.g. E 50) is common but it is not clear how those should be adjusted for Plaxis input. Two deep excavation projects and a lateral pile load test are used to see the performance of direct field curve fitting method utilizing SPT correlation to HS parameter. From the analysis, using E 50=4000N for clay soils and E 50=2800N for sand soils as upper bound parameters produce the best results with lesser discrepancy with the field measurements compared to calculations with lower bound parameters. For the deep excavation cases (Case 1 and Case 2), calculated lateral displacement results using upper bound parameters overestimates inclinometers measurement for less than 1.5 cm for both cases. For the case of lateral pile load test (Case 3), calculation using upper bound parameters succeed to capture a high detail of unloading-reloading curves similar to the actual measurement. This method can be used as a technique to design geotechnical projects and it proposes a framework for future research regarding a new possibility to establish various E 50 correlations.

In-plane seismic performance of precast concrete hollow-core slab panels for basement walls

In building structures, exterior basement walls should resist the soil pressure type earthquake load transmitted by the ground. Thus, the structural performance of the exterior basement walls is affected by in-plane seismic performance as well as out-of-plane load resistance. In the present study, for better constructability and cost-effectiveness of the exterior basement walls, conventional reinforced concrete walls were replaced with precast hollow core slab (HCS) panels. To investigate the in-plane earthquake load resistance of HCS for exterior basement walls, cyclic lateral loading test and numerical analysis were performed on four HCS panels with in-plane double curvature. The test and analysis results showed that the structural behavior of the HCS panels was significantly affected by the panel layout. In the test specimens using a single panel, flexural compression failure occurred at the bottom of the panel, and shear friction damage occurred at the upper and lower parts of the panel. In the test specimens using double panels, failure mode was governed by direct shear. The load-carrying capacity of the test specimens using double panels was greater than two times that of the test specimens using a single panel, because the load transfer changed from flexure into direct shear in the wall specimens using double panels. Further, to use HCS panels for exterior basement walls, a design method for prediction of in-plane seismic performance and yield displacement of HCS panels was proposed.

The behavior of reinforced concrete frames exposed to high temperature under cyclic load effect

Continued use of the structure through minor renovations and repairs without a complete and accurate determination of the extent of damage to the structure and its elements exposed to high temperature effects due to fire, etc. will cause more loss of life and property in the event of an earthquake that may occur later. The aim of this study is to determine the losses on the lateral load and energy damping capacities and stiffness of reinforced concrete frames exposed to 200, 400, 600 and 800 ℃ high temperatures for 60, 120 and 180 min. For this purpose, 13 reinforced concrete frame test elements with the same concrete and steel material properties and dimensions were produced. All reinforced concrete frame test members were brought to the specified target temperature within one hour and exposed to high temperature effects for 60, 120 and 180 min at these target temperatures. The test members then allowed cooling down on their own and when they reached room temperature, they removed from the oven and subjected to cyclic lateral loading tests. The data obtained from the cyclic lateral loading tests processed to obtain lateral load - horizontal displacement, stiffness - horizontal displacement, cumulative energy consumption - horizontal displacement and strength envelope curves for each test element. According to the results of the cyclic lateral loading tests, it was determined that the lateral load carrying capacities of the test members exposed to high temperature for 60, 120 and 180 min decreased by 24 %, 33.33 % and 36 % in push, and by 25.76 %, 37.6 % and 38.72 % in pull, respectively. In addition, the energy consumption of the test elements exposed to high temperature for 60, 120 and 180 min decreased by 30.98 %, 42.41 % and 39.62 %, respectively, compared to the reference test element. The initial stiffness of all test elements exposed to the high temperature effect decreased compared to the initial stiffness of the reference test element not exposed to the high temperature effect. According to these results, the effect of high temperature causes losses in many parameters that are of vital importance in the building elements, but also highly affects the earthquake behavior of the building.

Static lateral pile analysis of Dubai sedimentary rock in UAE

Analysis and calculation of lateral pile load capacities using appropriate methods is a challenging task for geotechnical engineers. Primarily, piles in Dubai, UAE, are rock fully socketed with top strata of medium dense to dense silty sand or sedimentary rock resisting lateral loads. In this study, the results of two field pile lateral load tests were chosen for examining different methods used by local geotechnical engineers, where ground lithology constitutes fragile sandstone up to ∼8 m below ground level overlying extremely weak conglomerate/siltstone. Assessing the efficacy of design parameters and analysis methodology is a pivotal aspect in preliminary evaluation of the lateral load capacity of piles. In this research, two commonly adopted approaches (non-linear p–y analysis using the LPile software and finite-element analysis using the Plaxis 3D software) were assessed by comparing them with field test results to predict the lateral load capacity precisely. Design parameters were based on borehole data and laboratory tests near the test location. Even though finite-element analysis predicted better than non-linear p–y analysis, lateral load capacities were underestimated in both piles analysed, which was related to assessment of input parameters. In addition, finite-element analysis was used to back-calculate the elastic modulus of rock that yields lateral deflections of piles close to field test results.

Pseudo-Dynamic Tests on Frame–Shear Wall Structure with Precast Concrete Diaphragm

In order to study how to improve the spatial action of precast monolithic composite floor slabs, and examine replacing the cast-in-place surface layer for reducing the weight of structure, we used pseudo-dynamic tests on one-quarter scale models of two-span and three-story frame structures. The lateral load tests compared the stresses and displacements with a cast-in-place floor frame–shear wall structure (SJ1) and a precast monolithic floor frame–shear wall structure with X horizontal braces at the bottom of the floor (SJ2). The results show the X horizontal braces can improve the spatial action. Structural integrity (SJ2) as well as the effective transmission of the horizontal force can be ensured by additional X bracing at the bottom of the rigidity of the floor without a cast-in-place concrete topping. The results show that X horizontal braces more effectively transfer horizontal stress, which provides a beneficial reference for similar research.

FDEM analysis of deep rock mass failure and its impact on horizontal bearing capacity in offshore wind turbine piles

Rock-socketed single piles are integral components of offshore wind turbine foundations in rock-based sea areas. Traditional numerical models have been employed to analyze the failure modes and lateral interactions between piles and the rock medium. However, these do not simulate the decline in the horizontal bearing capacity due to rock breakage, posing potential safety risks. In this study, the combined finite-discrete element method (FDEM) was used to simulate the deformation process of submarine rock masses transitioning from an intact to a fractured state. A notable innovation in the proposed approach is the consideration of the effects of the rock mass fracture and pile-rock cohesion on the load-bearing behavior of single-pile foundations. The FDEM model was validated through full-scale lateral load tests. The results showed a distinctive sequence in failure mechanisms, with the tensile failure of the rock mass around the pile at significant depths preceding the compression failure. Local failure at the contact interface significantly reduced the horizontal bearing capacity—a phenomenon that is inadequately represented by conventional finite element models. Furthermore, the cohesion element embedding method was introduced and used to simulate the influence of the tensile properties inherent in grouting materials on the failure strength and mode of the pile-rock interface. This study highlighted the importance of considering the nuanced effects of rock failure in the design of horizontally loaded piles. Failure to do so could lead to nonconservative designs and compromise the safety and efficacy of offshore wind turbine foundations. By pushing the boundaries of numerical modeling with the FDEM, the study aims to provide a more accurate and reliable framework for the design and assessment of rock-socketed single piles for offshore wind energy applications.

Behaviour of short columns made with conventional or FRP-confined rubberised concrete: An experimental and numerical investigation

Failure of short columns in concrete buildings has been extensively reported during past earthquakes. Assessing the behaviour of short columns is challenging and often requires using time-consuming advanced numerical modelling. This article presents a new and practical Short Column Macro Element (SCME) that predicts accurately the behaviour of concrete short columns. A 1/3-scale one-storey building with short columns is subjected to lateral loading tests until failure. The experimental results from the building are then used to calibrate a numerical model in Abaqus®. It is shown that the numerical model matches well the experimental results. The experimental crack patterns and stress distribution from Abaqus® are then used to determine the load path within the short column. Based on these data, a new strut-and-tie SCME is proposed and implemented in OpenSees software to simulate accurately (within 5% accuracy) the behaviour of the short columns of the tested building. Subsequently, the frame models calibrated in OpenSees and Abaqus® are modified to examine numerically the effectiveness of highly deformable FRP-confined rubberised concrete (FRP CRuC) at increasing the deformability of short columns with different levels of FRP confinement (1, 2 or 3 layers). The numerical results show that whilst the tested building failed at a small displacement of 5.4 mm (0.43% drift ratio), the use of FRP CRuC short columns with minimal confinement (1 layer of AFRP only) increased the building’s displacement by almost seven times to 37 mm (3.0% drift ratio). This also enabled more redistribution of forces to other structural members of the building. This article contributes towards the development of practical design/analysis models for short columns made of conventional concrete and FRP CRuC, which are scarce in the existing literature.

Comprehensive Evaluation of Lateral Performance of Innovative Post in Sand

Under environmental loads such as wind and earthquakes, piles are subjected to large lateral loads. A foundation system denoted Innovative Post (IP) that is composed of an H-pile shaft and one or two steel plates (paddles) welded to its flanges, has been developed to resist large lateral loads on sound wall systems. The present study evaluates the performance of IP installed in layered cohesionless soils through a comprehensive full-scale lateral load testing program and finite element (FE) analysis considering various pile and plate configurations. The developed FE model was validated employing the field test data and was then employed to conduct a parametric study to evaluate the performance of IP considering different paddles geometry (i.e., number of paddles, single or double, width, and length). The results demonstrated that adding the plates significantly increased the lateral capacity of H-piles. A positive relationship was identified between paddle’s width and length and the load efficiency. Optimal parameter values for paddles are established based on the experimental and numerical results proposed.

Experimental Investigation of Lateral Load Test on Diagonal Braced 3M Glass Fiber Reinforced Polymer Transmission Tower

Over the past decades, numerous research and development studies worldwide have focused on various civil engineering applications involving composite materials. Presently, recent investigations have explored the utilization of Glass Fiber Reinforced Polymer (GFRP) members in tower panels, composite cross arms in towers, full-scale 66 kV FRP double circuit towers, FRP towers created through filament winding techniques, GFRP triangular base communication towers, GFRP square base tower panels with bolted connections and strength and stability assessments of Glass Fiber Polyamide (GFP) towers and carbon fibre reinforced towers. The susceptibility of conventional TLT members to theft, where thieves often cut and steal them, prompted the suggestion to consider TLTs constructed with different materials. The study for examining the behavior of hybrid joints in angle-to-angle connections, with an ‘e/d’ ratio is 5. The well-performing hybrid joint has been implemented in a GFRP tower model and subjected to lateral loading to assess the effectiveness of such joints.

Seismic response and failure mechanism of ordinary concrete and UHTCC short columns reinforced with negative Poisson's ratio steel bars

The replacement of ordinary steel bars by negative Poisson's ratio (NPR) steel bars to improve the seismic performance of short columns is investigated in this study. NPR steel bars is a new type of reinforcement with negative Poisson's ratio effect and high strength and ductility. In this paper, six short column members were designed. Among them, P-RC1 and P-UHTCC1 short columns were used as controls, and the remaining four specimens were reinforced by NPR steel bars. The failure mode, cracking pattern, hysteresis characteristics, plastic deformation capacity, shear strength, stiffness degradation and energy dissipation capacity of the specimens were investigated through lateral cyclic loading tests. The experimental results showed that the shear capacity of short concrete columns reinforced with NPR steel bars increased by 20.91%−22.64% and the cumulative energy dissipation capacity increased by 45.7%−63.3%. The short UHTCC columns reinforced with NPR steel bars showed an increase in shear capacity of 23.08%−35.48% and an increase in cumulative energy consumption capacity of 17.3%−28.5%. And the RC columns shear strength prediction model based on GB50010–2010 specification is relatively reasonable to be used for the evaluation of shear strength of short columns reinforced with NPR steel bars.

An Experimental and Numerical Study on the Influence of Helices of Screw Piles Positions on Their Bearing Capacity in Sandy Soils.

Helical piles became a popular foundation technique, and as a result of environmental restrictions, they have become increasingly widely used. However, due to the high cost of experimentation, the influence of the number of helices and their positions on the pile-bearing capacity has not been sufficiently studied. The present study performed compression and lateral load tests on helical piles of the same diameter but with one, two, and three round helices in known sandy soil. The results from the experiments are compared with those from numerical simulations that use the mesh-free RBF method and the Winkler-Fuss approach to model how the pile and ground interact. The results are generalized to suggest an engineering equation that can predict the best pile configuration in sandy soil.

Cyclic Lateral Load Tests on Pile Segments in Sand

Cyclic Lateral Load Tests on Pile Segments in Sand