Lateral Load Research Articles

A Non-Weight Bearing Method for Measuring Hip Abduction Strength Overestimates Hip Abductor Muscle Fatigue During One-Leg Stance

OCCUPATIONAL APPLICATIONS Assessing workers’ strength capacities is a common practice prior to return to work following injury or illness, or assessing capabilities for strenuous jobs. Because it requires 50% or more of maximum strength capacity, hip abductor muscle strength is a strong predictor of both middle- and older-aged individuals’ ability to reliably balance on one leg and of their risk of falls. Our results suggest subjects were able to augment their hip abductor moment during unipedal weight stance via gluteus maximus activity. Weight-bearing hip abduction strength measures are important for assessing worker capacity for jobs requiring reliable unipedal balance whether during lateral loading, while walking in gusty winds, on slippery footing or resisting lateral deck movements on board ship or train. Measurements of hip abductor strength should be made in a full unipedal weight bearing posture; non-weight-bearing measurements significantly underpredicted hip abductor strength as well as endurance.

Shear behavior of reinforced concrete walls under variable axial tension‐compression and cyclic lateral loads

AbstractUnder a strong earthquake, the axial force of shear walls in tall buildings may vary from compression to tension, but few studies have been conducted on this. Three low‐aspect‐ratio reinforced concrete (RC) wall specimens subjected to coupled variable axial tension‐compression and lateral load were tested in this study, to investigate the effect of the fluctuating range of axial force and loading histories on the shear behavior of RC walls. The test results indicated that shear‐compression failure occurred under the compressive‐shear loading for all test wall specimens, and no obvious post‐peak strength degradation in tension‐shear loading. The hysteretic curves of test wall specimens were strongly affected by the loading histories; the shear strength and deformation capacity were mainly affected by the fluctuation of axial forces, especially for tension‐shear strength. The equation of ACI 318‐19 and JGJ 3‐2010 conservatively predicted the shear strength of RC walls under the variable axial force, while the equation of ASCE/SEI 43‐05 accurately predicted the shear strength with the mean values of the VTest/VASCE of 0.97 and 0.94 for compression‐shear and tension‐shear strength, respectively. Comparison with an RC wall under constant axial tension revealed that the failure modes of RC walls were strongly dependent on the initial cracking patterns. Finally, a finite element (FE) model was developed, and parametric analyses were carried out to further estimate the effect of variable axial force on the cyclic shear behavior of RC walls.

Modeling the deformation of thin-walled circular tubes filled with metallic foam under two lateral loading patterns

Thin-walled circular tubes with metallic foam fillers are widely used in various engineering fields. This work examines the plastic behavior of thin-walled circular tubes filled with metallic foam under two different lateral loading patterns, by using both analytical and numerical methods. Two types of loading indenters, including a line load and a rigid plane, are considered. There have been very few studies on the lateral compression of foam-filled circular tubes crushed by a line load or a rigid plane. The analytical models assume that the tubular wall material is rigid and ideally plastic, and that the metallic foam fillers maintain a constant resistance known as plateau stress. Using the principle of virtual velocities, we derive succinct explicit solutions for the crushing forces as well as deformation characteristics in regard with the radius of the tubes, the flow stress of the tubular wall and the plateau stress of the filled foam under the two loading conditions. Finite element analysis is performed using the ABAQUS2023/Explicit code to model aluminum alloy circular tubes filled with aluminum foam. A comparison and analysis of the deformation characteristics of the tubular top generator and foam cross-sections are conducted. The proposed analytical crushing forces and deformation properties obtained herein agree well with the numerical simulation results and outperform previous theoretical models, which may serve as valuable formulations for the engineering application.

Novel outrigger element utilizing thin steel plates as infill to concrete frames in concrete high‐rise buildings

AbstractRapid population growth and the need for sustainable land use have led to a remarkable increase in the construction of tall buildings. To accommodate the increasing need for floor space, high‐rise structural systems are being developed aiming to improve building performance against lateral loads. This paper introduces a novel steel‐infilled Reinforced Concrete Frame (SP‐RCF) outrigger and compares its structural performance against other systems, such as the Concrete Wall‐infilled Reinforced Concrete Frame and the Steel Truss‐infilled Reinforced Concrete Frame. A geometrically and materially non‐linear analysis was applied to these systems and validated through existing experimental and analytical data. Subsequently, a case study on a prototype tall building was conducted. The results indicate that the SP‐RCF outrigger shows superior performance compared to the other systems in terms of ultimate strength, stiffness, and ductility; demonstrating its potential to enhance the structural integrity of high‐rise buildings.

Development of reinforced concrete column with replaceable plastic hinge based on metabolism concept

To update seismic performance and rapidly restore the transportation capacity of a bridge following an earthquake, this study introduces a new reinforced concrete (RC) column, termed “Metabolic RC column,” which incorporates the Design for Disassembly and Metabolism Movement concepts. The proposed column features a plastic hinge comprising a permanent hinge and replaceable plastic zones. A Mesnager hinge is employed as the permanent hinge to resist the axial loads within the column cross section. In addition, cast-in-place RC members are used in replaceable plastic zones to dissipate the seismic energy. By replacing the plastic zone with an equivalent or superior alternative while the permanent hinge continues to carry the axial forces, the updating (i.e., metabolization) of the column seismic performance can be achieved without interrupting the daily operations of the structure. The feasibility of replacing plastic hinges while maintaining the resistance to axial loads was demonstrated through plastic zone replacement tests. Cyclic loading tests indicated that the maximum lateral load of the proposed Metabolic RC Column remained unchanged before and after the plastic zone replacement. The energy dissipated also remained nearly consistent before and after the plastic zone replacement. The largest reduction in dissipated energy at each displacement amplitude was approximately 6.7 % before and after replacement. Additionally, the cyclic loading tests emphasized the importance of minimizing damage to the permanent hinge and preventing the axial stiffness reduction to ensure maximum load capacity of the column after plastic zone replacement. Further, a numerical model was developed to replicate the load-displacement relationship of the specimens. The proposed model accurately calculated the maximum load of the specimen with an average error of approximately 3 % for each displacement amplitude and the dissipated energy with an error of approximately 6 %. The numerical analysis effectively captured the changes in the secondary stiffness of the columns before and after plastic zone replacement, attributing the differences in secondary stiffness to the reduced tensile forces exerted by the permanent hinge rebar.

Seismic Design and Ductility Evaluation of Thin-Walled Stiffened Steel Square Box Columns

This paper investigates the seismic performance of thin-walled stiffened steel square box columns, modeling bridge piers subjected to unidirectional cyclic lateral loading with a constant axial load, focusing on local, global, and local-global interactive buckling phenomena. Initially, the finite element model was validated against existing experimental results. The study further explored the degradation in strength and ductility of both thin-walled and compact columns under cyclic loading. Thin-walled, stiffened steel square box columns exhibited buckling near the base, forming a half-sine wave shape. The research also addresses discrepancies from different material models used to analyze steel tubular bridge piers. Analysis using a modified two-surface plasticity model (2SM) yielded results closer to experimental data than a multi-linear kinematic hardening model, particularly for compact sections. The 2SM, which accounts for cycling within the yield plateau and strain hardening regime, demonstrated enhanced accuracy over the multi-linear kinematic hardening model. Additionally, a parametric study was conducted to assess the impact of key design parameters—such as width-to-thickness ratio (Rf), column slenderness ratio (λ), and magnitude of axial load (P/Py)—on the performance of thin-walled stiffened steel square box columns. Design equations were then developed to predict the strength and ductility of bridge piers. These equations closely matched experimental results, achieving an accuracy of 95% for ultimate strength and 97% for ductility.

Fragility functions for structural-architectural shear walls with interlocking modules

ABSTRACT Tessellated structural-architectural (TeSA) shear walls, consisting of interlocking tiles, enable repairability because of modularization, and can satisfy both structural and architectural demands. This paper characterizes the behavior of TeSA walls made of 1-D interlocking reinforced concrete tiles using fragility functions. Two TeSA walls with varying tile patterns are analyzed under lateral loading. The modeling approach is validated using test results under quasi-static cyclic lateral loading. Damage states at tile and wall levels are defined, and a framework for generating fragility functions for TeSA walls is proposed considering uncertainties in the applied axial loading, tile-interface properties, modeling approach, and material properties of concrete. The results show that TeSA wall fragility functions are sensitive to tile shapes and patterns, particularly for the severe damage state. The onset of moderate and severe damage for TeSA walls is at 1% and beyond 2% drift ratios, respectively, showing high resistance of TeSA walls to damage.

Experimental evaluation of damage state and failure propagation of infilled frames under the opening effect

In this study, four frame specimens were tested: two with concentric window and door openings in the infills, and two with eccentric window and door openings. The serviceability limit of the infilled state was determined by evaluating the structural behaviour of infilled reinforced concrete frames with openings. The results indicate that frames with centrally located openings exhibit a reduction in lateral load capacity. The damage characteristics are influenced more by the location of the opening than by its percentage. When the opening is positioned closer to the edge of the masonry panel, the structural performance improves. Initial cracking occurs at a lateral drift of 0.2%, while crushing of the masonry panel occurs at approximately 2%. In frames with centrally located openings, the segment near the loaded column is more prone to damage, whereas the segment farther from the loaded column shows increased vulnerability.

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.

Effect of concrete strength on the seismic performance of circular reinforced concrete columns confined by basalt and carbon fiber-reinforced polymer

This paper investigated the effect of concrete strength on the seismic performance of circular reinforced concrete (RC) columns confined by basalt and carbon fiber-reinforced polymer (BFRP and CFRP). Eight confined columns and four control columns were tested under a low cyclic lateral load. The variables in the test included concrete compressive strength (i.e., 22.4 MPa, 31.4 MPa, 42.5 MPa and 57.8 MPa) and FRP type (i.e., basalt and carbon fiber). The test results demonstrated that all the columns exhibited flexural failure after confinement. The strength, ductility and energy dissipation capacity of the confined columns were effectively enhanced. With the same confining stress, the peak loads of the BFRP- and CFRP-confined columns were nearly the same. However, the BFRP-confined columns with low and moderate concrete strength showed larger ductility and energy dissipation capacity compared with the CFRP-confined counterparts, and these capacities of the CFRP-confined column with a concrete strength of 57.8 MPa were slightly better than those of the BFRP-confined equivalent. This showed that the FRP jackets with larger modulus had better confinement effect on the columns with higher concrete strength. Finally, formulas for calculating the load carrying and ductility capacities of different FRP-confined circular RC columns were proposed based on the experimental results.

Macro-element modelling for lateral response of monopiles with local scour hole via hyperbolic hardening relation

Monopile is a popular choice in the foundation supporting offshore wind turbines (OWTs), with local scour significantly impacting their lateral responses. Macro-element model, which encapsulates the response between the monopile and the surrounding seabed soils into a force-displacement relation, has been extensively developed to describe offshore foundations. However, such kind of models specifically targeting monopiles subjected to lateral loading in local scour remain underdeveloped. This work proposes a macro-element model with a succinct hyperbolic hardening relation for laterally loaded monopiles in local scour conditions, using the evolutionary polynomial regression (EPR) machine learning technique for easy and optimal design. First, the finite element model is verified and extended to generate force-displacement responses considering the monopile geometries, soil characteristics, and local scour geometries. These results are then utilised to determine the optimal hyperbolic hardening relation of the macro-element model. Next, the EPR technique is employed to determine the relationship between the hyperbolic hardening relation parameters and the influencing factors. Finally, the macro-element model is successfully evaluated by comparing with measurements from centrifuge tests and numerical solutions by finite element analysis, demonstrating its applicability in practical design and the ability to reproduce FEA results with a significant reduction in computational cost.

Connections between precast hollow concrete columns and foundations using UHPC and rebar lap splices

Hollow concrete columns (HCC) have been widely used in accelerated bridge construction worldwide. The column-foundation connections are vital in such precast systems to ensure seismic resilience. In this paper, a novel HCC-foundation connection using UHPC and rebar lap splices was proposed, which could facilitate the construction process. Cyclic tests were carried out on four specimens to examine their seismic performance. Test results showed that the proposed connections exhibited satisfying capacities, ductility, and energy dissipation comparable to monolithic connections under lateral cyclic loads. The use of a precast UHPC shell did not deteriorate the performance of the connection with no interface separation observed. The decrease in joint height would, however, bring about anchor rebar slippage and reduce energy dissipation. A validated fiber element model of the specimens was established for efficient seismic modeling of precast systems with the proposed connection in actual projects. Force transfer mechanisms and design methods for the connections were further deduced. The proposed connection has been verified to be comparable to cast-in-place connections and is thus suitable for use in precast column-foundation connections. Several design recommendations were derived for engineering reference.

Structural behavior of partially confined circular CFST columns under lateral cyclic loading

The seismic performance of concrete-filled steel tubular (CFST) columns is severely influenced by the failure at the potential plastic hinge zone. This paper proposes a novel confinement technique at the potential plastic hinge region using an inner circular steel tube for the circular CFST columns named partially confined concrete-filled steel tubular (PCCFST) columns. This confinement technique strengthens the plastic hinge region, and hence, the overall structural performance of the columns is enhanced. To verify the effectiveness of the proposed technique, a total of 7 columns: 6 PCCFST and 1 counterpart CFST have been tested under lateral cyclic loadings while subjected to constant axial load. Failure mode, hysteretic behavior, flexural capacity, ductility, and energy dissipation ability of the PCCFST specimens were investigated by varying the diameter and height of the inner circular steel tube. It was seen that the height of the circular inner steel tube has an obvious effect on the cyclic performance of the columns. For the PCCFST columns considered, the maximum lateral strength, ductility, and energy dissipation ability were enhanced by a maximum of ∼ 16 %, 24 %, and 14 %, respectively, when compared with the counterpart CFST column. A new design guideline has been proposed based on the Eurocode and limited experimental data obtained from the present study. A comparison between the experimentally determined maximum lateral strength and the proposed guideline has been made and is found to be in good agreement.

Finite Element Modeling and Analysis of RC Shear Walls with Cutting-Out Openings

In recent decades, reinforced concrete (RC) shear walls have been one of the best structural solutions to resist lateral load in high-rise buildings. Shear wall openings are essential for preparations and architectural requirements, which weaken the wall, reducing bearing capacity, energy absorption, and stiffness while also causing stress concentrations. This paper presents a comprehensive finite element (FE) investigation of the behavior and performance of RC shear walls with openings and subjected to lateral loads. The study aims to evaluate the influence of various parameters, such as opening location, size, wall aspect ratio, axial load, and concrete strength, which affect the performance of shear walls. FE models were developed to simulate the seismic response of RC shear walls under the combined effect of constant axial and lateral loads. The obtained results from the FE model showed a successful validation using the experimental data available in the literature. The FE analysis results demonstrate that the inclusion of lower openings leads to a 25% decrease in the bearing capacity of the wall when compared to the upper openings. Moreover, it was observed that augmenting the sizes of the openings and the aspect ratios of the wall resulted in declines in the strength, stiffness, and energy absorption capacity of the wall while simultaneously enhancing the ductility and displacement of the RC shear walls.

Sensitivity Assessment and 3D Finite Element Analysis of the Behavior of Bored Capped Pile in Sandy Soils Under Axial Tensile and Lateral Loading

Sensitivity Assessment and 3D Finite Element Analysis of the Behavior of Bored Capped Pile in Sandy Soils Under Axial Tensile and Lateral Loading

Experimental response of thin RC walls seismically strengthened with steel plates

In some Latin American countries, and especially in Colombia, the industrialized system of thin and slender walls has been chosen for the construction of residential buildings, thus reducing costs and increasing efficiency of construction processes. However, these walls differ considerably from traditional concrete wall system due to their reduced thickness, reinforcement detailing, and use of nonductile electro-welded reinforcement, which increases their seismic vulnerability, especially in tall buildings and in high seismic hazard zones. Strengthening proposals for walls with these specific characteristics of the industrialized system are scarce; therefore, it is necessary to evaluate alternatives that allow for improving their seismic performance. This article presents the experimental response of a thin wall that was brought to failure and subsequently repaired and strengthened with externally bonded steel plates to evaluate the effectiveness of the repair process and the strengthening. Additionally, the results of two thin walls externally strengthened with steel plates and bolts are presented, and their response is compared with that of the original walls. All the specimens were subjected to the same type of test under cyclical lateral load and constant axial load until failure. The behavior observed in the rehabilitated wall showed that it is possible to restore the stiffness of a wall that has previously been brought to a severe level of damage and increase its displacement capacity with the strengthening. In strengthened walls without previous damage, the displacement capacity was increased between 25 % and 43 %, reaching a roof drift of up to 2.0 % without a significant increase in resistance. A noticeable increase was obtained in the amount of dissipated energy (greater than 80 %), and the rupture of web reinforcement and buckling of longitudinal reinforcement of the boundaries were delayed for average drifts of 43 % and 32 % higher than in the original walls, respectively.

Thin-walled FRP-concrete-steel tubular tower with a top mass block subjected to lateral impact loading: Experimental study and FE analysis

Thin-walled hollow steel tube towers (HSTs), frequently utilized as a wind turbine tower, are facing challenges such as corrosion and local buckling in their service life. To enhance the anti-corrosion capacity and local buckling resistance, an FRP tube and an annular concrete layer can be employed to protect the HST, thus forming a novel member: thin-walled FRP-concrete-steel tubular towers (TW-FCSTs). Using a horizontal vehicle impact system, this study investigated the impact behavior of five large-scale TW-FCSTs, each with a top mass block to mimic the rotor and nacelle of wind turbine. All specimens were designed with a large diameter (300 mm) and a large void ratio (0.73 or 0.82). The experimental results revealed that: (1) Under lateral impact loading, TW-FCSTs displayed a global flexural failure mode, accompanied by localized concavity damage; (2) The inertial effect was enlarged by the top mass block, affecting the dynamic response of TW-FCSTs; (3) the increase of steel thickness led to higher energy dissipation but lower local deformation; (4) the increase of void ratio resulted in larger local deformation but smaller lateral global displacement. Finally, based on LS-DYNA, FE models were utilized to simulate the dynamic responses of TW-FCSTs with a top mass block.

Numerical Study on the Lateral Load Response of Offshore Monopile Foundations in Clay: Effect of Slenderness Ratio

To meet growing energy demands, offshore wind turbines (OWTs) with higher energy outputs are being developed, presenting increased challenges for their foundation design. Over the past decade, extensive research on the design optimization of OWT support structures has significantly reduced the anticipated costs of offshore wind farm development. Various design methods have been developed and applied in practice, each with its own advantages and limitations. In this study, 3D finite element (FE) modeling, validated against the measured response of a large-scale test monopile, is used to investigate the lateral load response of monopiles with different geometries and slenderness ratios in smaall and large displacements. The results are compared to the standard p–y method, and specific behavioral and design aspects of large-diameter monopiles, such as the moment contribution ratio from different resisting components and the minimum embedment length criteria, are evaluated and discussed. The results showed that the maximum and minimum differences between the 3D FE modeling and one-dimensional (1D) DNV p–y method are 41% and 11% for large displacements, and 32.5% and 13.3% for small displacements, respectively. As the slenderness ratio increases, the discrepancy between the finite element (FE) modeling results and the 1D DNV p–y method decreases, with an average difference of about 13% across all monopile diameters at an L/D ratio of 10, in both small and large displacements, indicating the reasonable accuracy of the 1D method for slenderness ratios of 10 and above. Among the three minimum embedment length criteria examined, the DNV recommended and vertical-tangent criteria offered shorter embedment lengths. The primary resisting moment across all slenderness ratios comes from the distributed lateral load along the monopile shaft (MCRp−y), which increases as the L/D ratio increases.

Effect of Lateral Load to the Behavior of Single Piles Subjected to Earthquake Load in Sand

In fact, pile usually carry static and dynamic load in same time, the case of simulations lateral and dynamic load is possible occurred. This case is not cover enough by previous researches especially by laboratory model. Therefore, the purpose of this study is to determine the extent to which altering the horizontal lateral loads impacts the behavior of individual piles during seismic events. An experimental test was devised using a physical model with an advanced shaking table that using El Centro earthquake. Sandy soil with 65% relative density used raining technique. Lateral loads were applied at levels of 0%, 50% and 100% from allowable lateral load capacity. It was observed that when lateral load increased from 0% to 50% and 100%, the lateral displacement response decreased by 32.10% and 49.59% respectively. While the vertical displacement increased by 49.96% and 76.95%. Finally, the acceleration decreased by 34.39% and 41.03%. This is possibly due to the load acts at an angle opposite to the earthquake as a restraining factor for the pile. led to a decrease in lateral displacement, vertical displacement, and peak ground acceleration.

Analytical Model for the In-Plane Lateral Capacity of Unreinforced Masonry Walls Based on Effective Compression Zone Failure Mechanism

ABSTRACT This study proposes a simplified theoretical model to predict the in-plane lateral capacity of unreinforced masonry (URM) walls, addressing limitations in current design guidelines based on semi-empirical approaches. Masonry walls are conceptualized as macroscale units subjected to vertical and lateral loads, with failure mechanisms governed by the effective compression zone. The model applicability is evaluated against comprehensive URM datasets and compared with existing guidelines. The results indicated the outperformance of the proposed model compared to existing guidelines. Additionally, a parametric study explores the influence of primary design parameters on the in-plane lateral capacities of URM walls, offering valuable predictive insights.