Lateral Resistance Research Articles

Seismic response assessment of tapered piles in sandy soils: A numerical investigation

For the same volume, tapered (non-prismatic) piles have premium advantages over conventional (prismatic) cylindrical piles with respect to the axial and lateral load resistance and, thereby, are considered an economical alternative to prismatic piles. While previous investigations have studied the behavior of tapered piles subjected to different dynamic loading conditions, their seismic response has not yet received a comprehensive examination. This study aims to investigate the seismic response of tapered piles in sandy soils using non-linear three-dimensional (3D) finite element analyses. A total of 3084 cases were studied using MIDAS software to consider a wide range of parameters, including variations in soil density (Dr), taper angle (θ°), slenderness ratio (L/DAvg), and different earthquake recorded data. A parametric analysis was also undertaken to investigate the behavior of the pile lateral displacement, pile bending moment, and frictional resistance. The findings of the study reveal that tapering enhances the lateral stiffness of the pile, resulting in reduced lateral deflections and decreased sensitivity to changes in L/DAvg and ground motion intensity. Furthermore, under higher ground motion intensity, improved pile stiffness through tapering contribute to an increase in bending moments experienced by the pile. Another significant observation is the substantial improvement in frictional resistance due to soil densification. This emphasizes the critical importance of considering the soil behavior and its density in the design of pile foundations, particularly when aiming to withstand seismic loads effectively. These insights offer valuable guidance for designing pile foundations that can reliably endure the dynamic forces present during seismic events.

Response of Batter Piles Subjected to Static and Seismic Loading: Review Study

Battered piles are beneficial when used as foundations where significant lateral resistance is required, which could result from extreme water waves, winds, soil pressures, massive hits of explosions, or earthquakes. Experimental and numerical research must focus on that direction to reveal how these foundations behave under different loading conditions. The present study reviews the investigations conducted on the performance of batter pile foundations and attempts to understand and cover various aspects related to this issue; after conducting the review, the results indicate that the negative battered piles provide an efficient lateral stiffness corresponding to positive battered piles and a vertical one. Also, lateral bearing capacity improved with the inclusion of battered piles. Moreover, batter piles respond better than vertical piles in liquefiable soil under seismic excitation. The current study also showed that the pullout capacity of batter piles increased with the batter angle.

Approximate analytical algorithm for pull-out resistance-displacement relationship of combined anchor system

Building upon an evaluation of the distinct advantages and limitations of anchor rods and anchorage plates, this paper introduces an integrated anchor-tensioning system that combines these elements in series. This innovative approach significantly enhances the pullout bearing capacity of the overall anchorage system. Based on the hyperbolic model of the distribution of lateral friction resistance of the anchor solid and the Winkler′s foundation model of load transfer of the anchorage plate, the theoretical analysis method for the analysis of the pullout bearing capacity and deformation of the combined anchorage system was established, and an approximate analytical equation for the relationship between pullout force and displacement was obtained. The results from indoor model tests, numerical simulations, and theoretical analyses were compared, verifying the reliability of the theoretical methods employed. The findings of this study significantly advance the discourse on the innovation of structural support configurations, thereby enhancing the operational efficiency of anchor-pull support systems.

A Review on Analysis of Seismic Impact of Improvements with Rigid and Semi Rigid RC Structure with having Podium

Abstract: The growing population and limited land in urban areas are driving up demand for towering buildings on a daily basis. India and other emerging countries are seeing an increase in the use of tall buildings. Land becomes unavailable for further expansion in any city, particularly in major cities, beyond a certain point of horizontal development. Consequently, multi-story skyscrapers gained popularity as a means of optimising land use. The design principles used for low- and mediumrise structures are not applicable to high-rise skyscrapers. Tall structures demand the most advanced design techniques since they are intricate engineering tasks. Architects and engineers proposed/put forward the new idea of Podium sort constructions in order to meet the demands of both the growing population and the present bye-laws requiring a minimum parking space for such types of buildings. These days, tower-podium style structures are quite common since they provide for the best possible use of available space on the property and the financial leverage to meet the need for more commercial space. A portion of a structure known as a podium has lateral load resistance greater than that of a tower.

A data-driven approach to quantify track buckling strength through the development and application of a Track Strength Index (TSI)

Railroads are increasingly adopting advanced technologies to enhance safety and state of good repair of their track infrastructure, some of which employ artificial intelligence-based inspection methods. The objectivity of these inspection techniques, along with their detailed measuring capabilities, has created opportunities for railroads to improve both inspection and operational efficiency. This is achieved through more frequent and precise track data collections and technical data aggregations. This paper explores the potential of these track inspection methods to address one of the few drawbacks of continuous welded rail (CWR): track buckling. While track buckling mechanics and prevention have been the subject of numerous studies, the need for a practical and objective method to assess resistance to buckling remains. Numerous track health indices for geometry parameters and some for railway components have been developed and utilized in various applications. Yet, the opportunity exists to develop a metric that combines geometric parameters with the condition levels of railway components, particularly designed to quantify the resistance of track to buckling. Such a holistic view of the track and network-wide time series analyses of the proposed metric demonstrate whether the buckling resistance improves, remains in a steady state, or declines. In this study, a sensitivity analysis conducted using CWR-Risk software identified misalignment amplitude, track curvature, lateral resistance, torsional resistance, and longitudinal resistance as the main factors contributing to buckling resistance. Based on the sensitivity study and with a focus on the capacity side of the track buckling equation, a methodology was proposed for converting inspection data into 10-point scales that were combined through weighted averaging into a single Track Strength Index (TSI) to quantitatively assess the resistance to buckling at a track-system level. The influence of ballast condition on TSI output was evaluated using 15 ballast configuration scenarios, ensuring that the index accurately reflects ballast deficiencies in a proportionate manner. Lastly, the proposed metric was tested leveraging revenue service data collected from a Class I railroad mainline in the United States.

Numerical modelling strategy and load resisting mechanism of palace-type traditional wooden frame

This paper is aimed at proposing the numerical modeling strategy of the palace-style traditional wooden frame in Chinese Song dynasty and revealing its load resisting mechanism. Firstly, the restoring moments of the column foot (CF) and column head (CH) of free-standing column are formulated, the proposed model of the frame with CF and CH is validated by the corresponding solid element models. Then, the mechanical behavior of the dowel at the CH is formulated based its deformation characteristics, and the proposed model of the frame with CF, CH and dowel is also validated by its solid element model. Finally, the effectiveness of the proposed model of the whole frame with CF, CH, dowel and dovetail mortise-tenon (DMT) joint is confirmed by the corresponding experimental and solid element models. The results show that difference of mechanical performance of the CF with compressive deformation parallel-to-grain and CH with compressive deformation perpendicular-to-grain is minor, the bending behavior of the dowel in the frame without lower beam has been changed into the shearing behavior of the dowel in the frame with lower beam. The rotational behaviors of the DMT at the two ends of the beam are different when the frame is lateral deformed, and the proportion of the lateral resistance provided by the column and DMT is more and less than 60 % and 30 %. And the upper beam of the wooden frame significantly increases its lateral resistance.

Low-cycle fatigue behaviour of concrete-filled double skin steel tubular (CFDST) members for wind turbine towers

Wind energy has the advantages of being clean and renewable. Wind turbine towers endure horizontal cyclic loads that could influence the performance of entire structure. To clarify the low-cycle fatigue behaviour of concrete-filled double skin steel tubular (CFDST) members, a total of 16 specimens were experimented. The hollow, slenderness, and axial compression ratios are specifically designed to clarify the effects on performance under constant amplitude loading and hysteretic loading conditions. The typical failure modes under both loading conditions and the relationship between loop strain, loop bearing capacity, loop energy dissipation, cycle number, and various degradation indices were analysed. Studies indicate that the failure mode under low-cycle fatigue loading is mainly local deformation, which includes transverse fracture occurring at the region between the steel tube and ribbed stiffener, the crushing concrete. Fatigue specimens with different amplitudes exhibit varying shapes of hysteresis responses. Higher amplitudes could enhance damage and significantly reduce fatigue life. Increasing the hollow and axial compression ratios boosts the energy dissipation capacity, and decreasing the slenderness ratio enhances the lateral resistance. A 2 % constant amplitude preload intensifies the degradation of bearing capacity and energy dissipation under subsequent constant amplitude loading.

Scours effects on the lateral bearing capacity of monopile-friction wheel composite foundations in sand-overlaying-clay deposit

The monopile-friction wheel composite foundation is recognized as an innovative offshore wind turbines (OWTs) foundation type, distinguished by its superior lateral bearing capacity and resistance to local scouring. In order to investigate the influence of local scour in sand-overlaying-clay deposit on the lateral bearing capacity of this new type of composite foundations, a series of numerical simulations are conducted to explore the effects of potential parameters including different scour parameters, overlying sandy layer thickness and loading point height on the lateral bearing performance. The results indicate that the greatest reduction in lateral bearing capacity of the composite foundation due to scour depth can reach approximately 35%, while the scour extent and angle have relatively small effects. Moreover, the lateral bearing capacity of the composite foundation increases with the thickness of overlying sandy layer. Local scour and the sand layer thickness also affect the lateral deformation and the soil resistance along the pile shaft. Furthermore, as the loading point height increases, the lateral resistance of the composite foundation decreases rapidly. These findings offer valuable insights for the design of monopile-friction wheel composite foundations in sand-overlying-clay deposits.

Soil-Pile Interaction of Laterally Loaded Fixed-Head Piles and Pile Groups in Unsaturated Sand

This study investigates the lateral behavior of piles in unsaturated cohesionless sandy soil using centrifuge modelling. The lateral loading was conducted on a single fixed-head pile and 2×2 fixed-head pile groups with 3D and 5D spacings. The results showed that the single fixed-head pile demonstrated greater magnitudes of lateral resistance response compared to the leading and trailing piles of the pile groups. Moreover, the piles experienced greater lateral loads when the water table was about a quarter of the embedded pile depth in the soil layer for the single fixed-head pile and leading piles in the group. The group efficiencies of the pile increased as the water table reduced up to half of the embedded pile length for the 3D pile spacing. However, this effect was negligible for 5D pile spacing. Considering the mixed unsaturated-saturated ground condition can lead to a more resilient foundation design under climate-induced and seasonal fluctuations of water table level and also pave the path for the inclusion of future climatic scenarios.

Lateral resistances of RC shear walls controlled by shear and sliding failure modes under axial tension

This study delved into the shear and sliding performances of RC shear walls subjected to combined axial tension and lateral shear, which may occur at the bottom of high-rise buildings under strong earthquakes. An extensive database comprising 41 RC shear walls tested under tension-shear was established, and the tests were categorized based on their failure modes. The study evaluated existing shear and sliding resistance models based on the collected database and introduced novel models for both shear and sliding resistances. The coefficients of variation for ratios of tested-to-predicted capacities of the proposed shear and sliding models are 0.18 and 0.24, respectively, significantly lower than those of the existing shear models and sliding models. A parametric analysis was conducted on the proposed models and the code models, and finite element results were used for verification. The results indicated that the proposed models not only effectively captured the influence of shear span-to-depth ratio, concrete strength, reinforcement ratios, and axial tensile force on the shear and sliding capacities of RC shear walls, but also well reflected the transition of shear and sliding failure modes. Furthermore, a numerical analysis was conducted to explore the impact of flange width on the shear capacity of shear walls. The numerical results confirmed that the proposed shear model effectively reflects the enhanced shear capacity due to the presence of flanges. However, predictions by ACI 318–19 and JGJ 3–2010 noticeably underestimated this effect.

Ground motion parameters and damage correlation in plan irregular L-shape steel structure with BRB

Irregularly designed structures frequently experience greater damage compared to regular buildings as a result of elevated torsional reactions and stress concentration, as indicated by evaluations of damage carried out subsequent to past seismic events. The irregularities in the plan configuration provide significant issues for building seismic design. One example of an irregularity is the re-entrant corners found in L-shaped structures, which can lead to early collapse by causing stress concentration from abrupt changes in stiffness and torsional response amplification. More than ever, a thorough investigation into the relationship between the issue of ground motion parameters (GMPs) and Damage is required because of the complex way that L-shaped buildings respond to earthquakes. The current study examines the relationship between a large number of commonly used GMPs and the associated damage for three-, six-, nine-, and twelve-story 3D buildings—that is, low-, mid, and high-rise structures—with asymmetric L-shaped plan layouts. The system of lateral load resistance that was used was Buckling Restrained Brace Frames (BRBFs). To assess a building's seismic performance, 15 bidirectional earthquake ground motions were applied using Nonlinear Time History Analysis (NTHA) for incident angles of 0°, 45°, 135°, 225°, and 315°. The structural response is reported in terms of the average and maximum inter-story drift as well as the total Park-Ang damage index. The relationship between GMPs and structural damage was then investigated using Pearson's correlation coefficient. The results indicate that the highest link with damage measurements is found for 3- and 6-story structures when looking at the spectral acceleration at the fundamental period, Sa(T1). However, PGD and SMV exhibit a stronger correlation than other GMPs for structures with nine and twelve stories. Additionally, Classification and Regression Trees (CART) is a decision tree algorithm used for predictive modeling. In this study suggested using CART (Classification and Regression Trees) algorithms to estimate the link between GMPs and Damage Indices. The findings demonstrate the ability of CART algorithms to extract the rules and correlations governing earthquake damage.

Novel Modeling for the Calculation of the Center of Lateral Resistance Position of Different Ships Making Use of a Full Mission Bridge Simulator and AI Tools

Novel Modeling for the Calculation of the Center of Lateral Resistance Position of Different Ships Making Use of a Full Mission Bridge Simulator and AI Tools

Influence of interfacial bond between rebar and concrete on the lateral resistance of RC columns under different loading rates

The interfacial bond between rebar and concrete is a critical factor that influences the performance of reinforced concrete (RC) structures because it affects the effective force transfer between concrete and rebar and hence the composite actions. In finite element modelling of RC structures, the bond-slip relation between rebar and concrete is generally neglected due to the increased model complexity by considering debonding behaviours. Limited studies show the debonding performance is loading rate dependent, neglecting it in numerical modelling may lead to inaccurate structural response predictions, but there is no systematic investigation of bonding performance on responses of structures under load of different loading rates. The influences of neglecting debonding in structural response analysis are therefore not properly defined yet. In this study, the finite element model was established and validated by the available impact test data. The lateral resistance and damage modes of the column considering and neglecting bond-slip behaviour between rebar and concrete were examined under various loading rates ranging from 50 kN/s to 1.0 × 106 kN/s. It is found that neglecting bond-slip relation in finite element modelling of RC columns leads to underprediction of the peak force and damage. The assumption of perfect bond has a significant influence on predicting the peak force and damage of column under low loading rates, but its influence reduces with the increase in loading rate, especially when the loading rate exceeds 1.0 × 105 kN/s. The maximum relative difference in peak force between considering and neglecting bond-slip at 50 kN/s is 18.63 %. Parametric studies were conducted to investigate the effects of bonding performance on columns of different width, depth, height, and concrete strength. Based on the numerical results, an analytical formula is developed to quantitatively predict the errors in peak force predictions by neglecting debonding between concrete and rebars of RC columns. The results highlight the importance of considering bond-slip in finite element modelling of RC structures subjected to quasi-static and low-rate dynamic loadings, and demonstrate it is reasonable to neglect debonding in structural response analysis under high-rate dynamic loadings.

Effect of the Particle Size Distribution of the Ballast on the Lateral Resistance of Continuously Welded Rail Tracks

While the effect of ballast degradation on lateral resistance is noteworthy, limited research has delved into the specific aspect of ballast breakage in this context. This study is dedicated to assessing the influence of breakage on sleeper lateral resistance. For simplicity, it is assumed that ballast breakage has already occurred. Accordingly, nine granularity variations finer than No. 24 were chosen for simulation, with No. 24 as the assumed initial particle size distribution. Initially, a DEM model was validated for this purpose using experimental outcomes. Subsequently, employing this model, the lateral resistance of different particle size distributions was examined for a 3.5 mm displacement. The track was replaced by a reinforced concrete sleeper in the models, and no rails or rail fasteners were considered. The sleeper had a simplified model with clumps, the type of which was the so-called B70 and was applied in Western Europe. The sleeper was taken into consideration as a rigid body. The crushed stone ballast was considered as spherical grains with the addition that they were divided into fractions (sieves) in weight proportions (based on the particle distribution curve) and randomly generated in the 3D model. The complete 3D model was a 4.84 × 0.6 × 0.57 m trapezoidal prism with the sleeper at the longitudinal axis centered and at the top of the model. Compaction was performed with gravity and slope walls, with the latter being deleted before running the simulation. During the simulation, the sleeper was moved horizontally parallel to its longitudinal axis and laterally up to 3.5 mm in static load in the compacted ballast. The study successfully established a relationship between lateral resistance and ballast breakage. The current study’s findings indicate that lateral resistance decreases as ballast breakage increases. Moreover, it was observed that the rate of lateral resistance decrease becomes zero when the ballast breakage index reaches 0.6.

Real-time detection of the lateral resistance of ballast bed during track realigning in tamping: A novel test method based on track shifting operation

Real-time detection of the mechanical state of ballast bed during the tamping operation in railway maintenance is of great significance for improving the effectiveness of operations. In this study, a novel test method named the track shifting test was proposed based on the track realigning operation of the tamping vehicle. The track panel was pushed by the shifting device. Moreover, the lateral resistance of ballast bed was reflected through easily measured indexes. An accurate coupling model of the shifting device and the ballasted track was constructed. Based on the model, the mechanical response of ballast and the track panel induced by the shifting load was analyzed. Results indicated that at an effective loading displacement of 2mm, the lateral resistance of ballast bed within a detectable range of up to five sleepers can be inverted by the shifting force and the displacement of sleepers. A machine learning model was established to obtain the mapping relationship between the shifting force, the displacement of sleepers, and the lateral resistance of ballast bed. Therefore, real-time detection of the lateral resistance was achieved by combining the proposed test method and the machine learning algorithm. This study can contribute to the synchronous detection of the mechanical state of ballast bed during tamping operation.

Effect of Soil Degree of Saturation on Pile Lateral Resistance at Different L/D Ratios

Effect of Soil Degree of Saturation on Pile Lateral Resistance at Different L/D Ratios

Novel accurate steady-state thermal resistance model for power chips embedded in TTSVs heat dissipation array

a novel oblique pyramid equivalent heat dissipation model is proposed for theoretically analyzing heat dissipation capacity of power chips with embedded TTSVs. Extra carefully researching correction of oblique thermal resistance, additional lateral thermal resistance, and thermal resistance of TSV insulation sleeve, the accurate theoretical thermal resistance model was established. Setting the FEA simulating results based on COMSOL Multiphysics as benchmark, heat dissipation effects of variation of radius of TTSV (r), thickness of the power chip (H0), and side length of the single cell (L0) have been numerically investigated. The maximum temperature relative error of the proposed model with FEA simulated results is not more than 0.2 %, 1 %, and 0.5 % for variation of r, H0, and L0, respectively. The proposed model has been theoretically and numerically proven to be effective and accurate.

The Effects of Vertical Load and Gaps on Lateral Resistance of Fork-Column Dougong in Traditional MultiStory Wooden Structures

ABSTRACT This article investigates the mechanical performances of the Fork-Column Dougong (FCDG), also named as Cha-Zhu-Zao Dougong, which is a common type of connection between the upper and lower columns in a traditional multistory Chinese wooden building. Numerical results of a typical FCDG under different vertical loads illustrate that the vertical load can strengthen the lateral stiffness of FCDG to some extent. Because existing FCDGs have different lengths of column limbs in their construction, the effect of this variation on the lateral behavior of the FCDG is also studied with reference to the different contact states between different components of the FCDG. The FCDG without gaps between its components gives generally better lateral behavior according to the lateral force-displacement curve. Because the column is the main member of the structure to carry the structural load transferred through by contact between the column limbs and the supporting Fangs. The length of column limbs would directly affect the effective contact area at the bottom and roots of column limbs, and the variation of the contact area would change the bearing capacity and load path of the FCDG. Results from this study may serve as reference to the restoration and protection of traditional Chinese wooden structures.

Experimental and theoretical studies on lateral behavior of prefabricated composite concrete-filled steel tubes truss column

Enhancing the lateral force resistance of residential structures through innovative prefabricated designs is crucial for improving structural resilience and safety. This study presents an innovative design for prefabricated concrete-filled steel tube (CFT) column trusses with V-shaped or Z-shaped configurations to enhance the lateral displacement and ductility of residential buildings under lateral forces. The CFT-column truss is a prefabricated system featuring two square CFT columns connected to H-section beams using fish plates. Additionally, the beams and columns are linked to a web truss component made of double-angle sections. To assess their failure patterns and characteristic capacities, two large-scale specimens were subjected to lateral monotonic loads. The test results indicated that both V-shaped and Z-shaped trusses exhibited exceptional performance. The V-shaped trusses demonstrated significant improvements in yield stiffness and ductility, increasing by approximately 22 % and 31 %, respectively. However, the yield and peak bearing capacities of these trusses were reduced by about 10 % and 6.75 %, respectively. Furthermore, a theoretical model was developed based on the observed test failure modes and verified through finite element (FE) analyses. The predictive results of the theoretical model were compared to a group of FE models, demonstrating their suitability for accurately estimating bearing capacities and yield stiffness with a high level of agreement.

Calibration of resistance factors for seismic design of masonry infilled frames using the random finite element method

This paper presents a reliability analysis of concrete masonry infill walls with an aim to examine the efficacy of the resistance factor specified in the infill design under seismic loading. A numerical model for masonry infilled reinforced concrete frames was developed and encoded in OpenSees for this study. The model was validated using experimental data. Two features were involved in this reliability study, including 1) that the effect of spatially varying masonry compressive strength f′m on the lateral resistance of masonry infills was considered using the Random Finite Element Method, and 2) that seismic load with different return periods was considered to provide a more complete treatment of a reliability analysis. The study selected six Canadian cities with varying levels of seismic intensity for this analysis. By calculating the probability of failure of infill frames subjected to earthquake loading at different locations, the paper showed that the current resistance factor of 0.6 in the infill design equation suggested by the Canadian masonry design standard is conservative. To achieve a reliability index of 3, this factor could be increased to 0.65 for all cities studied. For cities with low seismicity such as Toronto, the results suggest that an even higher resistance factor is justified.