Lateral Capacity Research Articles

Evaluation of Soil–Foundation–Structure Interaction for Large Diameter Monopile Foundation Focusing on Lateral Cyclic Loading

In this study, the monotonic and cyclic behavior of an offshore wind turbine with a monopile foundation installed in a sand layer were evaluated in the centrifuge. A simplified offshore wind turbine was modeled, and the lateral load was applied to the tower under displacement control. The monotonic loading test evaluated ultimate lateral load capacity and bending moment profiles under different loading levels. During cyclic loading, variations of moment-rotation responses, cyclic stiffness, and bending moments along the pile were observed. The initial rotational stiffness of the monopile decreased as the loading level increased. In the fatigue limit state (FLS) and service limit state (SLS) loading conditions, no noticeable variation in stiffness was observed with the number of cycles. However, in the ultimate limit state (ULS), the stiffness of the monopile increased during the first few cycles, followed by a decreasing rate of increase, and reached a certain value. The loading rate had a weakening effect on the monopile–soil interaction, which was supported by the bending moments induced in the monopile.

Frequency- and intensity-dependent impedance functions of laterally loaded pile groups in cohesionless soil

The frequency-dependent horizontal impedance functions of a model floating 2 × 2 pile group, embedded in cohesionless sand under a 1g condition, were investigated experimentally. The tests were conducted using large amplitude loads inducing soil yielding. The soil-pile system was housed in a laminar shear box fastened to the top of a unidirectional shaking table. Quasi-static and dynamic loads were applied in a lateral direction under the fixed pile-head condition to evaluate the force–displacement relationship and the horizontal impedance functions, respectively. The results of the quasi-static loading exhibited rate-dependent behavior for the lateral load-bearing capacity of the piles. Notably, the analysis of the soil surface near the piles, using a stereo-PIV calibration, demonstrated a consistent failure pattern despite the significant variation in velocity. Furthermore, an important observation was the convergence of the horizontal dynamic impedance functions towards the secant static stiffness as the amplitude of dynamic loading increased.

Experimental and numerical investigation of a new type of steel plate shear wall with diagonal tension field guiding stiffeners

A novel type of steel plate shear wall for withstanding lateral forces was proposed. Inclined stiffeners (acting as tension field guiding stiffeners) were added at the corners of the shear wall and a middle link beam was created, similar to the eccentrically braced frames (EBF). Therefore, upon adding diagonal members to the shear wall, the system resembled a combination of a steel plate shear wall system with an EBF system.To study the cyclic performance of the system equipped with the guiding stiffeners, a scaled specimen of the shear wall was made and subjected to cyclic loading. Finite element model of the wall was simulated and validated using the corresponding laboratory data. Then, a comparison between the proposed shear wall and the corresponding unstiffened steel plate shear wall was made. In the proposed system, the guiding stiffeners can alter the pattern of the tension field, pushing away the plastic strains from the column face toward the link beam. This helps the columns and connections remain intact. As a result, the system failure mechanism includes two-stage ductile fuses, including the steel plate yielding in tension, and flexural stresses or shear plastic hinges at the link beam ends. Compared to the unstiffened steel shear wall, the fuses help dissipate more energy in the proposed shear wall. In general, diagonal tension field guiding stiffeners can enhance the lateral force capacity, ductility, energy absorption, and stiffness of the system simultaneously.

Pure-bending yielding dissipater for the seismic retrofitting of reinforced concrete buildings with soft-story irregularity

Removing masonry infill walls from the ground or lower stories of buildings to make more open spaces, may lead to forming soft-story structural irregularities. Since considering the masonry infill walls as non-structural components is a common assumption in the evaluation of the seismic demand of buildings, there is a lack of knowledge dealing with the influence of the soft-story effect on the seismic response. In this study, the performance of 4-, 8-, and 12-story moment-resisting reinforced concrete frames with and without a ground soft story is compared first. Then, a proposal including the use of a yielding dissipater device to retrofit soft-story buildings is presented. The low cost, the simple manufacturing technology, and the same behavior in tension and compression, which makes the new axial force not imposed on the columns, are some of the advantages of this device. In order to assess the seismic performance of the proposed system, incremental dynamic analysis was conducted on the frames. Five states were considered for each frame: (a) bare frame, (b) fully-infilled frame, (c) ground soft-story frame, (d) and (e) retrofitted frames with two different configurations of yielding dissipater devices in the ground soft story. The responses of the structures are compared in terms of capacity curves, progressive damage curves, inter-story drifts, and story damage values. The results demonstrate that the frames equipped with the yielding dissipater devices experience higher lateral load capacity, lower overall damage, lower drift, and a lower damage value in the ground story than the soft-story ones.

Performance Case Study of Concrete Bridge-Rail Post on Deck Overhang

Concrete post-and-beam bridge rails are a common bridge-rail type in the U.S. However, direct investigations of their performance on bridge-deck overhangs are rare, and current specifications do not clearly address this rail type or the design of decks supporting them. In this paper, the results of a performance case study of concrete bridge-rail posts on deck overhangs are presented. This study included (1) bogie testing of a MASH TL-4 concrete post on an instrumented deck, (2) development and calibration of a corresponding LS-DYNA model, and (3) use of the calibrated model to further describe system behavior, evaluate the effect of common design alternatives on performance, and corroborate the system performance from a full-scale crash test. The results of this study indicated that current design methods of the AASHTO LRFD Bridge Design Specifications (BDS) resulted in a significant underestimation of lateral capacity, partially because their neglect of inertial resistance. In the bogie test of the concrete post, over 40% of the peak lateral resistance of the post was attributed to inertial effects. Similarly, the calibrated LS-DYNA model indicated that the full-scale system could withstand a simplified single-unit truck (SUT) loading consisting of a 150 kip pulse load while only sustaining minor damage, despite having a BDS-predicted capacity of 73 kips. Additional findings included a characterization of deck demands, performance effects of design alternatives, such as edge distance and slab thickness, and the influence of using straight versus hooked transverse deck bars.

Lateral bearing capacity and calculation method of pile-bucket foundation in clay for offshore wind turbines

Pile-bucket foundation, which attaches a wide-shallow bucket to the head of monopile, has been proposed for offshore wind turbines to improve the bearing performance of monopile foundation. In this paper, model tests were firstly conducted to investigate the lateral bearing capacities of monopile, mono-bucket and pile-bucket foundations, as well as providing a validation to finite element (FE) analysis. The results show that the bucket can effectively enhance the lateral bearing performance of the monopile foundation. Next, according to a series of finite element analysis, p-y curves in both reinforced section and non-reinforced section of pile component in pile-bucket foundation are modified considering the influence of the bucket component. The moment and lateral resistance provided by bucket component are calculated by limit equilibrium method. Consequently, by regarding the contribution of bucket as a restoring moment and lateral load, the pile-bucket is converted to a pile with external moment and lateral load acting on the pile head. A theoretical calculation method of pile-bucket foundation subjected to lateral loads is put forward based on modified p-y curves. This method is validated by FE results and can provide estimations of lateral loads and deflections for pile-bucket foundations under lateral loading in engineering design.

A macroblock 2D finite element model for assessing the roots of failure of Huaca de la Luna’s main pyramid (Peru) under seismic action

This study contributes to the seismic structural failure analysis of the main pyramid of the archaeological complex Huaca de la Luna, Peru. Built with millions of adobe bricks by the Moche civilization (200–850C.E.), the monument is one of the largest adobe structures in the world. The monument shows signs of severe natural and anthropogenic damage due to its position along the Pacific Ring of Fire and extensive looting since Spanish colonial times. The pyramid was built as a succession of taller and larger platforms, each formed by erecting adjacent but disconnected vertical piers made of adobe masonry. A multiscale 2D nonlinear finite element (FE) model is introduced for assessing the contribution of this pier architecture to the structural response of the pyramid. The time-evolution of elastic strain and plastic dissipation energies is used to quantitatively track structural failure. The instant of structural collapse and attendant lateral capacity can be extracted from the point at which these energies match. Critical regions of a representative cross-section are modelled with individual piers represented by macroblocks and separated by frictional interfaces. A continuous description is adopted for the remaining part of the model. A nonlinear, two-dimensional (2D) plane strain analysis is conducted in Abaqus/CAE Explicit using concrete damaged plasticity and Mohr-Coulomb formulations for adobe construction and soft soil, respectively. A two-stage assessment procedure begins with a quasi-static analysis to predict the stress state due to gravitational load. A dynamic analysis follows to identify lateral capacity and failure mechanisms triggered by monotonically increasing ground acceleration. The development of local damage conditions up to structural collapse is visualized by the nucleation and propagation of maximum principal plastic strains throughout the model. A sensitivity analysis was conducted to evaluate the effect on lateral capacity of the contact friction coefficient between macroblocks and the number of macroblocks used to discretize the critical area. Introducing macroblocks to the model produces lateral capacities that are lower than analogous, purely-continuum models. These results are shown to be critically affected by the frictional coefficient that governs contact between the macroblocks. The results of this study offer critical insights on the consolidation strategy for the northwest corner of the pyramid and may find application to similarly-built historical earthen structures in northern Peru.

Research and Optimization of Lateral Compressive Performance of the 3-D Printed Beetle Elytron Plate

In this paper, two types of beetle elytron plates (end-trabecular beetle elytron plate (EBEP) and middle-trabecular beetle elytron plate (MBEP)) and honeycomb plate (HP) were manufactured by 3-D printed and applied to large-span spatial structure. The lateral compressive performance of the 3-D printed beetle elytron plate was investigated by lateral compression bearing capacity test and numerical analysis. The influence of number of cylinders, ratio of the radius of the cylinder to the side length of the hexagonal honeycomb core (ratio of radius-length), thickness of core layer and configuration of beetle elytron plate on the lateral compressive performance of the beetle elytron plates were studied and the optimization method for lateral compressive performance of the beetle elytron plates was proposed. The result shows that the lateral compression bearing capacity of EBEP is greater than that of MBEP, and both are greater than of HP. The lateral compression bearing capacity of the beetle elytron plate with six cylinders is about 25% higher than that of the HP without cylinders. The lateral compression bearing capacity of beetle elytron plate can be improved by increasing the thickness of plates. The results of the study will promote the application of beetle elytron plates in large-span spatial structures.

Time dependent analysis of lateral bearing capacity of reinforced concrete piles combined with corrosion and scour

This study investigates the effect of chlorine corrosion and flow scour on the lateral bearing capacity of piles. A chloride diffusion model was established to obtain the initial corrosion time of reinforcement based on Fick's second law. The degradation of stiffness after corrosion is represented by a reduction coefficient. The finite difference method is used to solve the deflection differential equation of laterally loaded piles. The maximum scouring depth of piles in cohesive soil and the variation of scouring depth with time are calculated by empirical model. The calculated results from the analytical solution revealed that the pile stiffness decreases with the exposure time. As the time increase, the lateral displacement and shear force decrease on the other hand the bending moment increases. The increase of flow velocity and pile diameter results in the increase of the maximum scour depth around the pile. The bending moment, shear force, and lateral displacement of piles after scour increase significantly compared to the lateral bearing performance of piles before scour.

Behavior of frame-corrugated steel plate shear wall structure under cyclic loading

This manuscript innovatively presented a new type of assembled H-shaped steel frame-corrugated steel plate shear wall (HCSW). The hysteretic performance of assembled HCSW under cyclic quasi-static loading was investigated. The HCSW specimens with different corrugated steel plate thickness and axial compression ratio were fabricated. The H-shaped steel frame-flat steel plate shear wall (HPSW) was fabricated as control test specimen. The failure process, hysteresis curves, skeleton curves, lateral capacities, energy consumption and the other issues were discussed. The hysteretic performance of HPSW and HCSW was compared. It could be found that the hysteretic performance of HCSW was better than that of HPSW. The corrugated steel plate was yielded prior to frame column as a desirable sequence of material yielding. In addition, the finite element model was established to simulate hysteretic performance of HCSW specimen. The parameters included width-to-thickness ratio, width-to-height ratio, and axial compression ratio in this research. The effects of parameters on HCSW hysteretic performance were analyzed and discussed based on the finite element model. According to the research results, the recommended values of parameters were proposed based on the analysis results. Furthermore, the calculation formula of HCSW initial stiffness was presented. This research could provide a reference for the design and evaluate the application of current design of provision for assembled HCSW.

Seismic performance of steel-reinforced reactive powder concrete columns

The seismic performance of the innovative steel-reinforced reactive powder concrete (SRRPC) composite columns was evaluated via the cyclic experiments considering the steel shape ratio, axial compression ratio and the stirrup ratio. The SRRPC columns generally exhibited appreciable seismic behavior, great crack-resistance and excellent anti-spalling property. It was found that increasing the steel shape ratio from 4.20% to 5.35% can significantly enhance the ductility and the energy dissipation capacity. As the axial compression ratio increased from 0.1 to 0.3, the peak lateral load increased but the ductility significantly decreased. Increasing the stirrup ratio from 1.57% to 2.52% was not helpful for seismic performance in the pre-peak zone but was beneficial to the strength and ductility in the post-peak zone. Moreover, the average strength loss of the SRRPC columns with low axial compression ratio at the 4.5% drift ratio was less than 12.5%, satisfying the modern seismic drift criteria. Two coefficients, βtu and k, for predicting the equivalent tensile strength were identified and compared to the suggested values from the specifications JGJ/T 465-2019 and T/CCPA 35-2022, respectively. An analytical model was successfully developed to predict the lateral load-bearing capacity. Good agreements were found between the experimental and analytical results.

FEMA P695 seismic performance evaluation of Cold-formed steel buildings with different shear wall strengths and stiffnesses

Lateral load capacity and stiffness of CFS framed OSB sheathed shear walls can be improved by increasing the number of fasteners between sheathing panel and framing members or by providing sheathing on both sides of panel. Both of these methods could be a viable option to meet high seismic demands when the number of walls is limited by architectural or other concerns. With the increasing use of CFS building systems in high seismic regions, such applications are expected to be more widespread in the future. The present study aims to investigate the seismic response of CFS framed archetype buildings utilizing OSB sheathed wall panels with different levels of stiffness and shear resistance. Nonlinear time history analyses were conducted on 28 archetype buildings and collapse performance evaluation was performed according to FEMA P695 methodology. Load-displacement hysteresis behaviors of wall panels measured in a recent experimental study were adopted to simulate the shear wall response in the numerical models. Buildings utilizing shear walls that are sheathed with OSB panels on one side with 300 mm fastener spacing possess limited overstrength and fail to satisfy the performance criteria regardless of the response modification coefficient used for design. With the use of shear walls that are constructed with 50 mm fastener spacing and single or double sided sheathing configurations, the building design is governed by drift limitation instead of strength requirement. Irregular drift profiles occur with lateral displacements localizing at the first floor when shear walls with single sided sheathing and loose fastener layout is utilized. Using shear walls with a dense fastener layout results in a uniform distribution of lateral displacements among floors.

Study on seismic behavior of double leg C-type cold-formed thin-walled steel frame

The cold-formed steel (CFS) frame has the advantages of high strength, light weight, high construction efficiency, so it has been widely applied in building structures. However, the research on the seismic performance of multistory frames, especially those with braces, is rarely reported, the design method is also incomplete. In view of this, a pseudo static experiment of a three story double leg C-section CFS frame with brace is carried out. The bearing capacity, ductility, stiffness degradation and energy dissipation performance of the specimens are studied. The finite element analysis (FEA) method is used to simulate the failure process of the CFS frame and the design suggestions are proposed. The experiment result show that the failure process of the cold-formed thin-walled frame without braces has satisfactory ductility and energy dissipation performance; For framed CFS frame, the lateral stiffness and bearing capacity of the CFS frame increases, but the ductility decreases. Replacing double angle steel brace by steel plate strip brace can improving the seismic performance of structures, but there is an optimal width thickness ratio of steel plate strip. In this paper, the optimal width thickness ratio of brace is 5.0. When the design suggestions proposed in this paper are met, the CFS frame can achieve “strong structure, weak brace”, so as to improve the seismic performance of the frame.

Lateral bearing behavior and yield mechanism of Column-Flexible footing substructures considering SSI

Reinforced concrete (RC) isolated footing under column is a widely used footing type. In conventional structural design and analysis, superstructures are usually assumed to have fixed bases and the deformability of the footing and soil is ignored. However, the fact is that due to the natural characteristics of the footing, its inevitable deformation will directly affect the structural response of the superstructure. In this paper, to truly unravel the lateral bearing behavior and yield mechanism of the column-flexible footing substructures considering the soil-structure interaction (SSI), five column-isolated footing substructures placed on elastic composite blocks were tested with static pushover loading. Different from the traditional footing test, the soil is designed as a series of vertical independent elastic elements to consider SSI; the footing is designed to be flexible. The finite element (FE) model of the substructure is also developed for extended analysis. The test results show that the footing flexibility has a significant effect on the bearing mechanism and the subgrade reaction of the substructures. Analyzing the footing as rigid leads to an underestimation of the maximum soil pressure and an overestimation of the lateral bearing capacity of the substructures, especially for substructures with thin footing. In addition, the FE models of the RC frame with different footing relative stiffness factors are developed to systematically evaluate the effect of the footing flexibility on their seismic behavior and yield mechanism.

Parametric Studies on Seismic Performance of New Precast Braced Concrete Shear Walls under Cyclic Loading

A new precast concrete (PC) shear wall system with diagonal-shaped or cross-shaped concealed bracing was developed and experimentally validated, owning sufficient energy-dissipation capacity, in a previous study. Given that the seismic performance of such precast braced concrete shear (PBCS) walls is not comprehensively understood, this paper numerically investigates the influences of axial load ratio (ALR) and various reinforcement ratios (RRs) on the mechanical behavior of PBCS walls under cyclic loading. For this purpose, the numerical models based on the layered-shell element are developed to analyze the PBCS walls and validated regarding the deformation capacity of experimental results. A total of 156 PBCS wall models with different ALRs, longitudinal RRs of the boundary columns and bracing, and horizontal and vertical web RRs are established and tested under cyclic loading. It is concluded that the effects of bracing RR and horizontal web RR on the hysteretic responses are negligible and thus can be designed as the minimum suggested by the codes. However, the ALR, boundary column RR, and vertical web RR can significantly affect the lateral bearing capacity and displacement ductility of PBCS walls. In addition, the ALR limits for both types of PBCS walls are presented to satisfy the ductility requirements. Moreover, the simplified formulations regarding the bearing capacity and ductility of PBCS walls are proposed, respectively, which show good agreement with the numerical results. The outcomes of this research not only provide an in-depth understanding on the seismic behavior of the PBCS walls, but also promote the design code expansion and potential engineering application of such new types of PC shear walls.

Research on interaction relationship and seismic performance efficiency of corrugated steel-plate composite shear wall

In this study, the interaction relationship and seismic performance efficiency of composite shear walls were investigated. A previous experiment was reviewed to understand the failure mechanism of the composite shear wall, and the key parts of the structure were explored via simulation. Based on the simulation results with different parameters, the seismic performance sensitivity and interaction relationship of the horizontal corrugated steel-plate composite shear wall were analyzed. From a related analysis, the seismic performance efficiency of a composite shear wall was divided into five levels; the evaluation index was the column-to-plate shear ratio. The calculation formula for the composite shear wall was modified from the viewpoint of interaction. The results showed that when the shear ratio was greater than 1.45, the column had sufficient restraint to improve the efficiency of the corrugated steel plate; the composite shear wall had an optimal interaction. Additionally, the theoretical calculation of the lateral bearing capacity considering the interaction relationship was more accurate.

Fully demountable column base connections for reinforced CDW-based geopolymer concrete members

CDW-based concrete requires alkali-activators to generate geopolymerization process. These alkali-activators are difficult to be handled at the construction site and one of the rational ways to built reinforced geopolymer structures is the prefabricated construction. The connection of the precast structures is the most vulnerable component under the effect of seismic actions. Proper detailing and design of connections are crucial for sufficiently-ductile performance under seismic loading. Additionally, to achieve the disassembling and reusing of structural members, a demountable connection, i.e., dry connection, should be used instead of a wet connection. In this study, four novel fully-demountable connections for reinforced construction and demolition waste-based (CDW) geopolymer concrete members are developed. Seismic performances of these different demountable connections and one reference monolithic connections are experimentally investigated. The connections are subjected to reversed cyclic lateral displacements under constant axial loading. Comparisons are made referring to observed damage patterns, connection strengths, moment–curvature relations, initial stiffnesses, plastic hinge lengths, and energy dissipation characteristics of the proposed demountable connections and the monolithic connection. The results of the experimental study indicate that one proposed demountable connection exhibited larger lateral capacity and better seismic performance than its monolithic counterpart, whereas the other three proposals showed less performance than the monolithic counterpart.

Experimental Research on Seismic Performance of Masonry-Infilled RC Frames Retrofitted by Using Fabric-Reinforced Cementitious Matrix Under In-Plane Cyclic Loading

Fabric-reinforced cementitious matrix (FRCM) composites, also known as textile-reinforced mortars (TRMs), represent a new advancement in structural repair and reinforcement technology. Aiming to improve the energy efficiency and seismic performance of existing buildings, this research focused on the development of an FRCM system in combination with phase change materials (PCMs) and extruded polystyrene sheets (XPS) to achieve adequate mechanical and thermal properties for reinforced concrete (RC) and masonry structures. Accordingly, the in-plane behaviour of five FRCM-strengthened RC frames with hollow-brick wall infill was tested under cyclic loading to investigate the improvement in earthquake resistance. The system was comprehensively evaluated by calculating hysteresis curves; comparing the lateral stiffness, ductility, and energy dissipation capacity; measuring the deformations of the specimens; and analysing the failure modes mechanically. Finally, it was proved that this novel integrated approach could significantly enhance the mechanical and seismic performance of masonry-infilled RC frames.

Lateral bearing behavior and failure mechanism of monopile-bucket hybrid foundations on sand deposit

With the development of OWT technology, the requirement for bearing capacity of OWT is becoming stricter. A new type of monopile-bucket hybrid foundation has been recently proposed. As the bearing behavior and failure mechanism of the hybrid foundation have not been investigated comprehensively, laboratory experiments and numerical analysis of the monopile-bucket hybrid foundation subjected to H-M-T combined loads in sand are finished in this paper. Firstly, the model tests were carried out to explore the lateral bearing performance of the hybrid foundation with different loading eccentricity, skirt heights and pre-torque loads. Then, based on the numerical analysis, a quantitative analysis is proceeded to find out the influence of different factors on the bearing performance of the hybrid foundation in detail. The results show that, the lateral bearing capacity of the hybrid foundation is greater than the sum of bucket foundation and monopile. It's also found that the torque load has a strong weakening effect on the lateral bearing capacity of the hybrid foundation. Finally, an empirical calculated formula for calculating the lateral bearing capacity of the hybrid foundation in sand is proposed, which may provide a valuable engineering application reference for monopile-bucket hybrid foundation in sand under H-M-T combined loads.

Behavior of foundation piles resisting lateral forces in soft soil

The role of the foundation in construction is crucial. Foundation planning aims to ensure that it can support loads up to a specified safety limit, including the maximum load that may be encountered. The foundation serves as the lower structure that interacts with the soil, providing stability and support for the superstructure. In this study, the analysis focused on the bearing capacity of the pile foundation under lateral forces. The Brinch Hansen method was employed to determine the allowable lateral bearing capacity, while the computer application was used to calculate the lateral deflection. Various pile lengths, such as 20m, 25m, 30m, 34m, and 40m, as well as different dimensions, including circular piles with diameters D30, D35, D40, and square piles measuring 30x30, 35x35, and 40x40, were considered. The analysis revealed that square cross sections exhibited greater allowable lateral bearing capacity compared to circular cross sections. The square sections showed smaller lateral deflection values in comparison to the circular sections.