Lateral Load Research Articles

Analysis Seismic Behavior of Structures with Planar Imperfections: A Comprehensive Numerical Analysis

This paper presents a comprehensive approach to the seismic analysis and design of a tall hospital building, accounting for horizontal irregularities and employing equivalent static analysis (ESA) methodology. The study initiates with the collection of relevant site data and building specifications, including the identification and characterization of horizontal irregularities such as setbacks, mass distribution variations, and irregular floor plans. Equivalent static lateral loads are calculated based on applicable building codes and standards, taking into account the effects of horizontal irregularities on seismic response. Structural modeling and analysis are then conducted using sophisticated software to evaluate the building's behavior under seismic forces, considering the influence of irregularities on structural performance. Design criteria, encompassing drift limits, strength requirements, and detailing considerations for mitigating irregularity effects, are rigorously adhered to ensure compliance with safety regulations and performance objectives. The iterative process of evaluation and adjustment ensures optimal seismic performance and adherence to design criteria despite the presence of horizontal irregularities. Documentation of the analysis and design process, coupled with meticulous construction oversight, guarantees the implementation of a robust seismic design strategy tailored to the unique characteristics of the tall hospital building. Post-construction evaluations are carried out to validate predicted seismic performance, accounting for the influence of horizontal irregularities. Through collaborative efforts and adherence to best practices, the seismic design of the tall hospital building prioritizes safety and resilience, even in the face of horizontal irregularities, aiming to safeguard occupants and critical healthcare infrastructure during seismic events.

Failures of geometrically asymmetric steel-UHPC composite beams

Geometrically asymmetric steel-ultra-high performance concrete (UHPC) composite structures (SUCSs) suffer several typical failure modes during applications in structural engineering. But the competing mechanism of these failure modes remains a challenge to be urgently overcome. In the present paper, the failure modes of the geometrically asymmetric SUCSs under lateral loads are theoretically predicted and numerically studied. Considering both the geometric asymmetry of the structure and the tensile-compressive asymmetry of UHPC, a theoretical model is proposed to predict the critical failure load for each failure mode (e.g., bending and core shear), and then a failure mechanism map is constructed by comparing each critical failure load. The theoretical predictions are in line with the present numerical results and the previous experimental measurements. The results demonstrate that geometric asymmetry, together with some other geometric parameters and material properties, have remarkable influences on the failure modes of structures. This work provides an effective approach for predicting and designing the failure modes of geometrically asymmetric SUCSs in structural engineering applications, such as undersea tunnels, offshore platforms, and nuclear shielding walls.

Finite element analysis of locally strengthened stainless-steel tube under lateral impact loading

In this study, a Finite Element (FE) model of locally strengthened high-strength stainless-steel tube subjected to lateral impact loads is established using LS-DYNA to investigate its dynamic behaviours. The accuracy of the FE results is verified by comparing with the test results. The impact force, bending moment, stress and strain responses as well as the internal energy dissipation histories of the strengthened tube are analysed during the entire impact process. The results indicate that the impact resistance of the strengthened tube is obviously enhanced as compared to hollow stainless-steel tube. Furthermore, parametric studies are conducted to reveal the influence of axial compressive force, impact position, impact velocity and material strength on the impact behaviour of the strengthened tube. The results show that the application of axial compressive force reduced the impact force and increased the deformations of the strengthened tube. The impact resistance of the strengthened tube performed an increasing trend when moving the impact position towards the support and increasing the material strength. In addition, the increase of impact velocity significantly reduced the impact duration. Finally, design recommendations and process were proposed to facilitate the application of locally strengthened tube.

Seismic Performance of Full-Scale Autoclaved Aerated Concrete Panel-Assembled Walls: Experimental Study and Numerical Modeling

Prefabricated panel-assembled wall systems, comprising a confining frame and infill lightweight panels of autoclaved aerated concrete (AAC), are widely employed in framed structures. Different from studies on a main frame with infill walls, this study aimed to explore the seismic performance of partition walls, which were fabricated with AAC panel-assembled walls and located outside of the main frames. Two full-scale specimens, one with a door opening and the other without, were constructed and cyclic loading tests were executed to examine the failure modes, hysteresis characteristics, envelope curves, ductility, strength and stiffness degradation, as well as energy dissipation capacity of the AAC panel-assembled walls. Additionally, a restoring-force model for the panel-assembled walls was developed and a method for predicting the lateral load-bearing capacity of the AAC panel-assembled walls was proposed. The findings indicated that the panels enhanced the system’s lateral resistance, energy dissipation capacity, and deformation capability. The door frame increased the initial stiffness, peak lateral load and energy dissipation capacity of the AAC panel-assembled wall compared to the wall without a door frame. Compared to the specimen without a door frame, the peak lateral load of the specimen with a door frame increased by 19.7–30.1%. The deformation capacity of the panel-assembled walls aligned with the requirements for concrete framed structures.

Seismic performance of flexural reinforced concrete columns subjected to varying axial forces

This paper examines the influence of variable axial force on the seismic performance of flexural domain reinforced concrete (RC) columns through experimental testing of five full-scale specimens. The test results demonstrate that fluctuating axial force, when combined with simulated cyclic seismic loading, significantly impacts the flexural behavior of RC columns. The behavior of RC columns under fluctuating axial loads was markedly different from that of columns under constant axial loads. A notable observation was that the failure mode of the columns transitioned from ductile flexural failure to flexure-shear failure when comparing columns subjected to constant axial loads to those subjected to fluctuating axial loads that alternated between compression and tension. This study further demonstrated that the lateral load capacity of the columns, along with their deterioration, was significantly influenced by both the fluctuating pattern and intensity of the axial forces, as well as the displacement ductility. An empirical equation was proposed to estimate the residual lateral load capacity of flexural domain RC columns under varying axial forces, providing a practical tool for designers to assess the behavior of columns under different loading conditions. To corroborate the conclusions drawn from the experimental investigation and gain further insights into the influence of fluctuating axial force on the seismic behavior of flexural domain columns, this study additionally proposes a finite element (FE) model. According to the experimental and numerical results, an empirical equation to estimate the ultimate drift capacity of RC columns subjected to varying axial force is also proposed.

Experimental study on seismic performance of squat RC shear walls reinforced with hybrid steel and GFRP rebars

This laboratory study investigates the effect of using steel and glass fiber reinforced polymer (GFRP) rebars in shear walls with aspect ratios less than two. The study evaluates six full-scale shear walls subjected to constant axial load and cyclic lateral loading, with aspect ratios of 1.08 and 1.75. The aim is to analyze how the use of steel and GFRP rebars affects crack patterns, fracture, seismic performance, dissipated energy, and ductility of shear walls. The six specimens consist of two reference ones (SRC1 and SRC2) reinforced with steel rebars, two specimens (GRC1 and GRC2) reinforced with GFRP rebars, and two specimens (S-GRC1 and S-GRC2) reinforced with a hybrid of steel and GFRP rebars. The conclusions drawn suggest that employing a hybrid combination of steel and GFRP rebars resulted in a notable alteration of crack propagation behavior and failure mode, transitioning from flexural compression to flexural tension. Additionally, compared to the specimens reinforced solely with GFRP rebars, there was an observed expansion of the hysteresis curve. Additionally, parameters such as cumulative dissipated energy, ductility, and load modification factor based on ductility increased in the S-GRC1 and S-GRC2 specimens compared to the GRC1 and GRC2.

Water, Salt, and Ion Transport and Its Response to Water-Saving Irrigation in the Hetao Irrigation District Based on the SWAT-Salt Model

Soil salinization is one of the main hazards affecting the sustainable development of agriculture in the Hetao Irrigation District (HID) of Inner Mongolia. To grasp the water and salt transport patterns and spatial–temporal distribution characteristics of the HID at the regional scale, the improved Soil and Water Assessment Tool with a salinity module (SWAT-Salt) model was used to establish the distributed water and salt transport model for the watershed in this study. The results demonstrated that the modified model could more accurately represent the process of water and salt changes in the HID. The coefficient of determination (R2) in the simulation of streamflow and discharge salt loading was 0.83 and 0.86, respectively, and the Nash–Sutcliffe efficiency (NSE) was 0.80 and 0.74, respectively. Based on this, different hydrological processes (surface runoff, lateral flow, groundwater, soil seepage) as well as spatial–temporal distribution characteristics of water salinity in groundwater and soil were analyzed in the HID. Differences in groundwater and soil salinity in different land uses and soil types were also compared. Of these, surface runoff and lateral flow salt discharge loading are concentrated in the southwestern portion of the basin, while groundwater salt discharge loading is concentrated in the eastern as well as southwestern portions of the basin. The salt discharge loading from groundwater accounts for about 98.7% of the total salt discharge loading from all hydrological pathways and is the major contributing part of salt discharge from the irrigation area. Soil salinity increases gradually from west to east. Groundwater salinity (2946 mg/L) and soil water electrical conductivity (0.309 dS/m) were minimized in the cropland. Meanwhile, rational allocation of irrigation water can appropriately increase the amount of salt discharge loading. In conclusion, the model could provide a reference for the investigation of soil salinization and water–salt management measures in irrigation areas.

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.

Effects of Fluid Viscous Damper on Reinforced Concrete Tall Building under Lateral Loading in Lagos, Nigeria

The rapid construction of tall buildings in unconventional areas of Lagos, driven by high land cost necessitates meticulous analysis and design to withstand lateral loads such as wind and seismic forces. Typically, enhancing structural rigidity is the conventional approach to counteracting horizontal loads. This study examines the effectiveness of fluid viscous damping (FVD) in reducing gravity, wind and seismic loads in a 24 – story suspended floor frame structure. Using ETABS 2019 software, the building’s modeling and analysis demonstrate that integrating FVDs at each floor level significantly reduces displacement, drift and overturning moments by 20%, 24%, and 29%, respectively, thus enhancing structural stability. Analyzing structural response in Nigeria, despite low seismic intensity, is crucial for risk management and resilience. It informs building practices, improves building codes, and prepares for potential seismic events, ensuring safer infrastructure. This research provides a computational framework for dampening vibrations in tall buildings through FVD technology.

Comparative analysis of two intergranular strain-based hypoplastic models through elemental and centrifuge testing

While hypoplastic models have demonstrated accurate predictions of sand behavior under monotonic loading, their accuracy diminishes when applied to cyclic loading conditions. To address this limitation, the intergranular strain approach is used as an extension to the model. The current investigation focuses on the analysis of two variants: the original Intergranular Strain (IS) approach proposed by Niemunis and Herle (1997) and the Intergranular Strain Anisotropy (ISA) by Fuentes et al. (2019). Although both models have the same objective, they present distinct mathematical structures and therefore different repercussions on the simulations. In this study, sand Hypoplasticity is enhanced with IS and ISA, and employed to simulate a series of experimental tests conducted on Fontainebleau sand. These tests encompass isotropic compression, drained monotonic triaxial, and undrained cyclic triaxial tests, while considering different initial densities and test characteristics. Furthermore, the calibrated models were applied to simulate a series of centrifuge tests, involving a pile embedded in the same sand, which is subjected to various episodes of monotonic and cyclic lateral loading. A comparison and discussion of the similarities and differences in elemental and finite element predictions, arising from the two intergranular strain formulations is presented.

Behavior of Exterior Beam-Column Joints Steel Fiber Reinforced Self-Compacting Concrete (SFRSCC) Against Cyclic Lateral Loads

Behavior of Exterior Beam-Column Joints Steel Fiber Reinforced Self-Compacting Concrete (SFRSCC) Against Cyclic Lateral Loads

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.

In-plane behaviour of masonry infill walls with openings strengthened using textile reinforced mortar

A numerical study was carried out to simulate the in-plane behaviour of a 1:2.5 scaled one-storey one-bay masonry-infilled reinforced concrete (RC) frame retrofitted with textile-reinforced mortar (TRM). The study used ABAQUS finite element analysis (FEA) software and a three-dimensional (3-D) finite element method. Using a ductile design and details, the TRM-reinforced structure encountered in-plane displacement-control cyclic loads during the test. This study assesses how accurately a representative numerical model can replicate the results of an experimental test. Parametric research was conducted following the numerical model's calibration. To develop a suitable numerical model, suitable constitutive models based on the concrete damage plasticity (CDP) approach were used to characterize the nonlinear response of TRM, masonry infill, and concrete. The experimental findings, which aggrandize the response simulation, served as the basis for calibrating the models. Using a finite element framework and the simplified micro model technique, the masonry structure is simulated at the infill component level. The numerical model demonstrated accurately the ability to simulate the in-plane behaviour of the modified RC frame with infill walls, including its initial stiffness, deterioration, deformation-resisting ability, and failure patterns. Furthermore, a parametric study was conducted to determine the significance of the full-bond scenario between the RC frame infilled with masonry and the TRM considering: (1) the location of the strengthening material on the specimen and (2) the number of layers of the strengthening material. All retrofitted wall specimens showed a considerable improvement in in-plane performance; some features of the wall's behaviour were found to be strongly influenced by the parameters under examination. It can be observed that the specimen with two layers of TRM on both sides of the infill wall exhibit the maximum lateral load carrying capacity and maximum deflection resisting characteristics while the other retrofitted specimens controlled the deflection to some extent and significantly enhancing the load carrying capacities of the masonry system.

Lateral loading response of monopiles in sand considering installation effect

The effect of pile installation is a critical issue in the analysis and design of pile foundations but it is commonly ignored due to various numerical difficulties. In this paper, the installation process of an open-ended pipe pile into a sand deposit is simulated by using the zipper technique combined with the Arbitrary Lagrangian-Eulerian (ALE) method in the framework of three-dimensional (3D) finite element modeling. The subsequent lateral load response of the pile is also simulated and compared with that without consideration of the pile installation. The state dependent behavior of sand in associated with the pile installation and the subsequent lateral load is described using an advanced constitutive model. The study shows that for a relatively loose sand deposit, the sand surrounding the pile exhibits contraction and the disturbance zone takes the form of a trapezoid, whereas for a dense sand deposit, the sand near the pile will dilate and the disturbance zone takes the form of an inversed trapezoid. Furthermore, the deformation mode of the surrounding sand under the lateral load differs to some extent from that without consideration of the installation effect. Particularly, the location of the rotation point for the laterally loaded pile tends to move downwards when the pile installation process is considered.

Analysis of Base Shear and Story Drift in the Low-Rise RC Sructure

<p class="Abstract">Earthquakes frequently occur in Indonesia because it is an earthquake-prone area. Due to lateral load from an earthquake can cause a weakly constructed building to collapse. Designers often only consider tall buildings in designing earthquake-resistant building structures but ignore earthquake-resistant designing for low-rise buildings. This study focuses on the analysis of earthquake resistant structures with a case study of low-rise buildings in the form of a 3-story reinforced concrete (RC) building in the South Jakarta area. The objective of the study is to analyze the base shear and story drift of the structure due to lateral or earthquake loads. The structure is a reinforced concrete with the concrete compressive strength of <em> </em>= 30 MPa and longitudinal reinforcement of  = 420 MPa and stirrups of    = 280 MPa. This study uses equivalent static analysis manually and using ETABS 20.1.0 application. The results showed that three story buildings analyzed using equivalent static analysis method and using ETABS 20.1.0 application had almost the same results on horizontal forces with manual result of 1680.97 kN and ETABS of 1648.46 kN. The elastic story deflection and inelastic story drift in this study are still within safe limits because it is below the drift limit.</p>

Foundation Types of Fixed Offshore Wind Turbine

Offshore wind turbines are supported by various foundations, each with its considerations in design and construction. Gravity, monopile, and suction bucket foundations encounter geotechnical issues, while jacket and tripod foundations face fatigue problems. Considering this, a gravity foundation based on a steel skirt was developed, and a monopile foundation was analyzed for Pile-Soil Interaction using the p–y curve and 3D finite element method (3D FEM). In addition, for suction bucket foundations, the effects of lateral and vertical loads were analyzed using 3D FEM and centrifuge tests. Fatigue analysis for jacket and tripod foundations was conducted using a hotspot stress approach. Some hybrid foundations and shape optimization techniques that change the shape to complement the problems of each foundation described above were assessed. Hybrid foundations could increase lateral resistance compared to existing foundations because of the combined appendages, and optimization techniques could reduce costs by maximizing the efficiency of the structure or by reducing costs and weight. This paper presents the characteristics and research directions of the foundation through various studies on the foundation. In addition, the optimal design method is presented by explaining the problems of the foundation and suggesting ways to supplement them.

VARIASI SHEAR KEY TERHADAP STABILITAS DINDING PENAHAN TANAH KANTILEVER BETON BERTULANG

Stability parameters are very important in the analysis and design of reinforced concrete cantilever retaining wall structures. One of the parameters to increase the stability of this retaining wall is to add a shear key structure. Shear keys can increase wall stability, resist shear, increase stiffness, resist lateral loads, and increase load capacity. The purpose of this research is to determine the level of stability (overturning and shearing) of reinforced concrete cantilever retaining walls by varying the shear key dimensions with the same cross-sectional area. The method used is a quantitative method using data on the properties of soil materials, reinforced concrete, and the geometry of retaining wall structures. The analysis uses the help of Geo5 software, which is geotechnical software for solving problems in the geotechnical field. In this research, four models of reinforced concrete cantilever retaining walls have been created, including model 1 (b/h = 0), namely the model without a shear key, model 2 (b/h = 1), namely square shear key, model 3 ( b/h = 1/4) is a vertical rectangular shear key and model 4 (b/h = 4/1) is a horizontal rectangular shear key. The results of the analysis produce rolling stability with an increase in rolling moment and a decrease in moment of resistance on average of 8.32% and 4.43% respectively for the model without a shear key with a maximum rolling safe factor in the horizontal rectangular shear key model of 2.24. Likewise, the shear stability of the model with a shear key results in an increase in ground shear force and a decrease in active shear force on average of 11.76% and 105.93% respectively compared to the model without a shear key with a maximum shear safe factor in the horizontal rectangular shear key model of 3.96.

Embodied carbon premium for vanity height: A case for the exclusion of decorative spires in the design of tall buildings

In measuring the height of a tall building, the Council on Tall Buildings and Urban Habitat (CTBUH) recognises three categories: “height to architectural top”; “height to highest occupied floor”; and “height to tip”. The “height to architectural top” category, which includes decorative spires, is used to define the influential CTBUH annual rankings of the “World's Tallest Buildings”. The inclusion of decorative spires in the category ranking has created an incentive for developers to maximise the vanity height of tall buildings, defined as the height difference between a tall building's architectural top and its highest occupied floor.The aim of this paper is to demonstrate the detrimental influence of spires and, by extension, vanity height on the embodied carbon of structural systems for tall buildings. This influence is evaluated using three tall building scenarios of varying heights (50, 70, and 90 storeys). Two finite element models, with and without spires, are parametrically designed for each scenario. All the modelled structural systems comprise a reinforced concrete tube-in-tube lateral load resisting system. A hybrid life cycle inventory analysis approach is used to quantify the embodied carbon of spires as well as the resulting increase in the embodied carbon of structural systems.The findings of this study indicate that even basic spires can lead to an increase of up to 14.2% in the embodied carbon of structural systems for tall buildings, underscoring the imperative to eliminate such elements in the design and construction of tall buildings to minimise overall embodied carbon.

Effect of type of internal core on the behavior of diagrid tube systems under lateral seismic loads

Diagrid structural systems have emerged as innovative and adaptable structural systems for tall buildings. These structures contain diagonal truss elements throughout the height of the structure. The present study investigated the effect of an inner steel moment frame core and an inner concentrically-braced core on a diagrid tube system under lateral seismic loading. The effect of inner cores on ductility and failure of the structures was assessed. A 36-story composite diagrid structural system with three different arrangements of diagonal angles was considered and the response spectrum analysis and nonlinear static analysis were conducted. The diagrid structures with inner cores indicated that most of the transferring lateral force in all stories is tolerated by the diagrid system; only in the last story was the shear absorbed by the internal core. Analytical results show that as the slope of braces increased, the lateral strength decreased. Diagrid structures with an inner braced core indicated greater ductility and strength than diagrid structures with inner moment frame cores. Moreover, the results indicate that the diagrid tube with an inner core produced no significant increase in ductility. To avoid premature buckling of braces, perimeter diagonal braces should be replaced with buckling-restrained elements.

Simulation of Preload Relaxation of Bolted Joint Structures under Transverse Loading

In this study, based on the Iwan model, the connection interface of the bolted joint structure subjected to lateral loads was simulated and comparatively analyzed. Commercial finite element software was used to model the bolted joint structure. Monotonic lateral loads and cyclic displacement loads were applied to the model. The changes in the preload force of the bolted connection structure, as well as the changes in the sticking zone and stress state of the connection interface, were analyzed, and the loading results of monotonic load and cyclic displacement load were compared. The results show that the contact interface stress decreases with the increase in displacement load, and this increase is also a nonlinear relationship, which is approximately in phase with the trend of the contact surface slip curve. The amount of contact surface stress loss and the amount of preload loss are not directly related to the magnitude of the initial preload, regardless of the loading conditions. The contact surface is also circular under any form of displacement loading, whether it is stressed or slipped. The amount of preload loss is proportional to the amount of bolt compression for that variable.