Lateral Load Research Articles

Quantitative research on stress failure risk assessment for girth welds with unequal wall thickness of the X80 pipeline under lateral load

The cumulative length of the X80 steel pipeline extends to 17,000 km, with a predominant portion traversing mountainous terrains characterized by intricate geological formations. Recurrent geological hazards significantly impede the safe operation of oil and gas pipelines. Landslides can induce substantial axial forces on steel pipelines, significantly increasing the risk of pipeline failure. Moreover, as a result of sudden changes in mechanical structure, the pipeline's unequal wall thickness leads to local stress concentration, making it more vulnerable to external loads than the steel pipeline itself. Therefore, to analyze the mechanical response of steel pipelines under different working conditions, we establish a smooth particle hydrodynamics, finite element transverse landslide pipeline model for girth welds with unequal wall thickness and investigate a tearing accident caused by a lateral landslide in a section of the large-diameter natural gas pipeline. The landslide volume is found to be the main controlling factor for the failure of pipeline circumferential welds. According to the genetic algorithm backpropagation neural network, the von Mises stress of the most dangerous section of the pipeline is calculated based on pipeline and landslide parameters, and the error is 11.67 %. According to the API RP 581–2016 Risk-Based Inspection Methodology, a failure risk assessment matrix is established using the pipeline statute as an evaluation indicator to evaluate the landslide risk to pipelines in different regions. A variable-wall-thickness girth weld on the ZG pipeline was selected for application. This method has good applicability for evaluating the failure risk of circumferential welds with wall thicknesses of 12.8/15.3 mm under the action of small landslides.

Seismic Upgrade of an Existing Reinforced Concrete Building Using Steel Plate Shear Walls (SPSW)

Steel Plate Shear Walls (SPSW) provide significant lateral load capacity and can be utilized in the seismic retrofit and upgrade of existing reinforced concrete (r/c) buildings. In this study, the application of SPSW to retrofit a r/c building designed according to older seismic provisions is presented. Three different options to model SPSW are utilized, i.e., by equivalent braces, by finite elements, and by membrane elements, seeking not only to appropriately simulate the actual behavior of the SPSW but also to achieve the desired seismic behavior of the retrofitted building. Specific seismic response indices, including plastic hinge formations, are derived by non-linear time-history analyses in order to assess the seismic behavior of the retrofitted r/c building. Inspection of the results provided by non-linear analyses in conjunction with the different modeling options of the SPSW leads to the conclusion that the model with the membrane elements exhibits the best performance, implying that for the seismic retrofit and upgrade of existing r/c buildings, the use of membrane elements to model the SPSW is recommended.

Experimental and numerical evaluation of seismic behavior of coupled walls connected by post-tensioned, unbonded, precast concrete coupling beams

To investigate the seismic performance of coupled shear walls, which are connected by post-tensioned, unbonded, precast concrete coupling beams (PCCB), two 1/7-scale experiments with 8-story coupled shear walls under cyclic lateral loadings were conducted. Coupling of concrete shear walls is achieved by post-tensioning concrete beams to the wall piers using unbonded post-tensioning tendons (UPT) at the floor and roof levels. Experimental results show that little damage occurs in the coupling beams and the wall regions when the specimen undergoes large nonlinear displacements. The residual displacements of the specimen are small because of the restoring effect of the post-tensioning force. The seismic performance of three systems including CW-RC (coupled wall systems that use traditional RC coupling beams), CW-UP (coupled wall systems which use only post-tensioning tendons without steel reinforcement through the beam-wall joints), and CW-HUP (shear walls and PCCB that use combinations of steel reinforcement and post-tensioning tendons) are evaluated by means of nonlinear dynamic analysis. The calculation results indicate that the inter-story drift and peak lateral displacements of CW-HUP and CW-UP are greater than that of CW-RC, whereas the residual deformations are reduced because of the self-centering effect of the post-tensioning tendons.

Seismic performance of Fe-SMA prestressed segmental bridge columns with 3D printed permanent concrete formwork

The integration of digital fabrication technology with prestressed segmental column construction offers significant potential for accelerated bridge construction with material-efficient design. This study aims to explore this potential by developing a novel prestressed segmental column system that utilizes permanent 3D printed concrete (3DPC) formwork for column segment fabrication. Prestressing is achieved in the proposed system by using partially bonded iron-based shape memory alloy (Fe-SMA) reinforcement. Large-scale experiments were conducted on two columns under combined gravity and lateral loading to evaluate the seismic performance and feasibility of the proposed system. The ratio of steel to Fe-SMA reinforcement in the column design was the variable considered in this study. The experimental results showed that the columns could withstand lateral drifts of up to 5% without collapse and the permanent 3DPC formwork showed no premature failure or delamination. Furthermore, the columns exhibited self-centering characteristics, maintaining a residual drift of 1% up to a target drift of 4% when the reinforcement ratio of steel to Fe-SMA rebars was 0.3. The results highlight the potential of the proposed prefabrication concept in designing material-efficient and seismically resilient bridge columns with low damage characteristics.

Experimental investigation of model piles subject to lateral load in cohesionless soil

In this research work, the way piles behave in sandy soil and are exposed to lateral forces was examined experimentally by using several lab examinations. These tests were performed on a model of steel piles, including a closed-ended circular pile, a closed-ended square pile, and an H pile. The outcomes of the experimental tests were presented as load-displacement diagrams to examine how pile length and shape affected lateral load capability. Moreover, along the length of the pile, the bending moments were obtained and presented as relationships between the bending moment and the pile length. Therefore, it can be said that piles' capacity to support lateral loads rises with increasing pile length for each of the study's pile shapes. Additionally, it finds that the H-pile has a greater lateral load capacity and maximum bending moment than other piles.

An innovative experimental device for characterizing the responses of monopiles subjected to complex lateral loading

Offshore wind turbines are usually founded on monopiles. During the operation period, the structure is subjected to complex lateral loading from wind, wave and current. The soils surrounding those monopiles may deform with increasing the number of loading cycles, leading to tilting of the whole structure; hence, it is vital to carry out physical model tests to examine the long-term performance of monopiles. This study proposes an innovative experimental setup for centrifuge modelling of the response of monopiles under complex lateral loading. Hydraulic actuators are adopted to apply lateral loads on model pile, and electrohydraulic servo-valves and associated controllers are used to achieve a closed loop position or load control. A carefully designed spherical hinge and load bars are used to connect the model pile and actuator shafts. This enables that the pile can rotate freely and can move vertically freely. A centrifuge test on a winged monopole subjected to perpendicular lateral loading was carried out at 100g. The experimental results shed light on pile responses in the cyclic loading and constant loading directions.

Evaluating The Basement Design of Low-Rise Building with Two-Stage Analysis using BIM Integration: Hangar Study Case

Building Information Modelling (BIM) has revolutionized the way the construction industry designs, constructs, and manages buildings. Certainly, the utilization of BIM can optimize the usage of materials in a construction project, considering the high level of concrete consumption globally and its significant environmental impact. The implementation of BIM is intended to calculate the volume of concrete and steel material usage in the design process of low-rise buildings with basements, exemplified in this case by a 5-story laboratory hangar with a 1-story basement. The building design is carried out through a two-stage analysis, which involves separating the upper portion from the lower portion of the structure. This analysis procedure is commonly conducted in building design with basements. When designing the lower portion, some practitioners often neglect the lateral soil forces in the global model when designing the column and beam elements, assuming that these forces are sufficiently small and can be accommodated by basement wall reinforcement. In this research, with a shallow basement depth configuration, the study compares the extent of differences in structural dimensions and materials caused by these lateral forces. Significant variations in volume are observed in perimeter columns, primarily due to direct soil loads acting on this area. Additionally, considering the function of these columns as boundary elements for the basement walls, such differences are expected. The application of lateral soil forces on basement walls is determined by the specific basement configuration being designed. This includes assessing whether there are additional walls outside the basement walls, which can be analyzed locally since they are assumed to bear the lateral soil loads occurring. Different analyses yield varying reinforcement and concrete volumes in basement structures, especially between models with and without lateral soil loads, resulting in a 7.73% difference in reinforcement and 4.69% difference in concrete volume.

Determination of deflections of above-ground pipelines under loads in the longitudinal and transverse directions

The most common method of construction of field pipelines in permafrost-dominated areas is above-ground laying on supports. The size of the span between bearings is determined taking into account the condition of tuning out resonance frequencies in case of vortex excitation due to wind load. For these purposes it is necessary to determine the natural frequencies of vibrations of above-ground pipeline sections. When determining the natural frequencies of pipeline sections, it is necessary to take into account the initial position caused by additional loads in longitudinal and transverse directions (pre-stressed state of pipeline sections). A differential equation for determining the position of a pipeline section under stationary loads in longitudinal and transverse directions based on the rod theory is obtained. The numerical solution of the equation is obtained using the finite difference method. The influence of longitudinal and lateral forces is evaluated. It is shown that the influence of longitudinal and lateral loads has a significant effect on the initial position of pipeline sections. Therefore, the complex influence of loads should be taken into account for the correct determination of deflections. The initial position of the pipeline under the action of various combinations of loads can be used to evaluate the preliminary stress-strain state in the design of above-ground pipelines.

Comparative analysis of RCC and PT Slabs underneath Lateral Loading: A Structural study using ETABS

ETABS software is used to analyze the structural response of reinforced concrete (RCC) and post-tensioned (PT) slabs under lateral loading. This study investigates RCC and PT slabs’ behavior by using finite element analysis to determine bending moments, shear forces, and storey drift. Prestrassed slabs display lower bending moments and shear forces than RCC slabs, demonstrating the effectiveness of prestressing in reducing structural requirements. A reduction in storey drift also indicates improved resistance to lateral deformations in PT slabs. In terms of structural performance and cost-effectiveness, PT slabs offer potential benefits for constructing layouts and construction, making them an attractive choice.

Generic and simplified approaches for the structural analysis of precast concrete sandwich panels

This paper presents a comparison between three numerical models developed for the structural analysis of composite precast concrete sandwich panels under lateral loading. The first model is based on a full finite element analysis where “slip” between the layers is obtained from the elastic deformability of the various components. The second model is based on a simplified finite element analysis where the effect of the shear connectors is smeared and modeled through an effective shear stiffness of the insulation layer. The third approach provides closed-form expressions for evaluating the deflection and is based on the classical sandwich beam theory where the shear connectors are considered through the effective stiffness of the insulation, similar to the second model. The structural response obtained from the three models was compared for various panel configurations and good correlation was obtained. A reasonable agreement with test results from the literature was also demonstrated. Therefore, both the simplified finite element model and the classical sandwich beam theory (closed-form solution) are recommended for the elastic structural analysis and for estimating the degree of composite action at the serviceability limit state of precast concrete sandwich panels.

Lateral Displacement Behavior of IBS Precast Concrete Elements Reinforced with Dual System

Throughout history, the construction industry has been a significant contributor to construction waste, presenting an ongoing challenge in efficiently managing this waste to mitigate environmental pollution. The Industrialized Building System (IBS) stands out as a construction approach that utilizes prefabricated components made from various waste materials, implemented with machinery and formwork, leading to minimal waste production. The potential failure of IBS blockwork columns under lateral loads is a significant concern, and the deformation of these columns is crucial in assessing overall structural performance against lateral forces. This study focuses on examining the deformation and flexibility of components in IBS blockwork columns when subjected to lateral loads. Using Finite Element Modeling (FEM), a 1:5 scale prototype model of the dual-reinforced system IBS Block Work Column is analyzed. The IBS Block Work Column, comprising four prefabricated components assembled in the form of a crucifix plan to enhance lateral stability, is subjected to FEM analysis and experimental investigations. The study aims to explore the impact of four different shapes of reinforcement on deformation resistance. The findings suggest that employing a dual-reinforced system in the IBS Block Work Column enhances its resistance to lateral loads compared to a column with conventional reinforcement. Moreover, the assembled IBS Block Work Column exhibits greater stiffness than a single prefabricated component when subjected to lateral loads. Doi: 10.28991/CEJ-2024-010-01-020 Full Text: PDF

Thin layer interface: An alternative modeling consideration in soil-structure interaction system

The numerical modeling of a soil-structure interaction (SSI) system subjected to lateral loads depends mainly upon the interface behavior. The soil stiffness in relation to the structure is quite low, and the structure generally has a rough surface in contact with the soil. As a result of the slipping and rolling of soil grains caused by friction, a thin layer of shear zone forms in soil with the application of lateral loads. A thin layer interface is represented by the shear zone. As a result, the decision on the thickness requirement is critical for appropriate modeling of the thin layer interface, which is rarely documented by researchers. Furthermore, it has been reviewed in the literature that modeling the SSI system with a thin layer interface more accurately replicates the physical system than modeling it with a zero-thickness interface. The methodology for effective usage (in terms of proper interface thickness) of the thin-layer interface in SSI system using finite element (FE) modeling is proposed in this work. The thickness of the interface has also been determined via numerical modeling of a large direct shear test (DST).

Parametric study of depth to maximum bending moment for prestressed concrete piles resisting lateral load

Seismic design of prestressed concrete piles requires transverse spiral reinforcement to be proportioned to confine and thus retain an intact concrete core during inelastic rotation cycles. Prescriptive provisions of the International Building Code require a prescriptive minimum volumetric ratio of confinement reinforcement relative to the pile cross section and a minimum in-ground depth to which the confinement reinforcement must extend. This study seeks to determine a practical maximum depth to maximum in-ground bending moment for 12, 14, and 16 in. (300, 360, and 410 mm) prestressed concrete piles subjected to displacement consistent with lateral seismic loads. A commercially available lateral analysis software was used to conduct a parametric analytical study of square and octagonal piles embedded in substantially varied soil conditions. Piles were modeled to remain elastic. Depth to maximum in-ground moment was recorded. Maximum depth values for each pile type were reported. Analysis of results indicates that prescriptive depth requirements may be overly conservative for 12 and 14 in. square piles in nonliquefiable soils. It was concluded that a reduction could be made to the code-prescribed depth of ductile reinforcement for some pile types in nonliquefiable conditions.

Inversion of Lateral Impact Load Migration History and Trajectory Location Method for Deck Structures Based on the Time‐Slicing Method

Inversion of Lateral Impact Load Migration History and Trajectory Location Method for Deck Structures Based on the Time‐Slicing Method

Monitoring and Assessment of Buckling in Slender Members with Varying Lateral Restraint and Thermal Loading Using Distributed Sensing

Monitoring and Assessment of Buckling in Slender Members with Varying Lateral Restraint and Thermal Loading Using Distributed Sensing

Predição da capacidade última de elementos em concreto armado usando metodologias de análises não linear

Abstract This work aims to investigate the ultimate capacity of reinforced concrete elements in terms of cracking and stiffness loss. Nonlinear finite element analysis (NLFEA) was performed in the ATENA software and compared with a proposed numerical simulation of nonlinear static analysis (NLSA), where material cracking is evaluated based on the loss of tangent stiffness of the elements. The analysis was applied to a low-rise reinforced concrete frame with constant axial loads in the columns, and monotonic lateral load applied at the top beam level. Both methodologies showed good agreement regarding the capacity curve and crack patterns, and the numerical simulation NLSA allowed the identification of the sequence of elements' stiffness loss. The results indicated a substantial similarity between the numerical simulation NLFEA and NLSA and the experimental test, indicating a high potential in predicting the nonlinear behavior of reinforced concrete.

Seismic Evaluation of Retrofitting Technique Using Bracing Systems for Steel Multi-Story Building

A bracing system is the one of effective retrofitting methods for existing high buildings to support the lateral loads. Structural bracings increase the stiffness and stability of the building and the energy dissipation capacity. In this research, the numerical study of retrofitting a multi-story steel building near Imam Ali Holy Shrine in Najaf, Iraq has been conducted. The retrofitting mechanism includes a test of four different bracing systems such as X-bracing, V-bracing, Diagonal-bracing and IV-bracing located in the x and y-axis of the model. The seismic analysis using the elastic response spectrum method was performed for two types of earthquakes, weak and strong. The comparison among different parameters is discussed such as maximum lateral displacement, story drift ratio and base shear values. The seismic load was applied in two axes of the building model simultaneously and the results of the parameters in the x and y-axis were extracted. The results show that the retrofitting using four bracing system types increases the capacity of energy dissipation of the existing building model to seismic load by reducing the maximum lateral displacement in the x-axis by 55%, 44%, 41%, and 30% for X, IV, V and Diagonal-bracing, respectively. However, the X-bracing has a significant increase of the shear base value of the model by 39% and 49% in the x and y-axis, respectively, which means cost-effective compared with the other bracing types. Therefore, the IV-bracing type has an appropriate effect on the strength of the building against seismic load with reasonable cost-effectiveness.

Analysis and Design of an Unsymmetrical Multi-storey building with floating columns in a seismic zone using ETABS

Most high-rise structures today are designed with floating columns for aesthetic purposes and the need for efficient use of space. Lattice columns are vertical load-bearing elements that do not extend the entire height of the building, they are usually located on one or more intermediate floors and support beams. These design innovations have benefits such as increased architecture and space allocation. Loads include load and side load. Heavy loads, including dead loads and live loads, are evaluated to determine the overall load distribution. Lateral loads resulting from earthquakes and wind forces are calculated based on local building codes. In seismic design, multistorey buildings with floating columns are analysed at different levels on curved planes to determine safe floating column locations. Structures can be analysed with symmetric information and dynamic analysis methods such as response spectrum or potential time. Preliminary analysis and equivalent static analysis using ETABS 2022. A 3D structural model was created to accurately represent the geometry of the building and its behavior under different load combinations was used to compare the building's response to seismic forces. The result is the behavior of the structure: shear strength, bending moment, deflection, and displacement. The results are obtained in the form of tables and graphs. The structures were built with M30 concrete and various types of steel. Reinforcement spacing and detailing is done in CSI Detail.

Cyclic Lateral Load Tests on Pile Segments in Sand

Cyclic Lateral Load Tests on Pile Segments in Sand

Assessment of Bullet Impact and Failure Mechanism of Concrete Containing Polythene Aggregates

The time from the initial stage of existence on Earth, the war continued. In this concern, India’s DRDO (Defence Research and Development Organization) and OFB (Ordnance Factory Board) worked appreciatively to develop new protective gear against assault weapons. The main focus of bullet or blast proof structures is to safeguard the life of soldiers, their accessories and gears, along with confidential and classified acquittance, firearm and ammunition, and sensitive systems. Defence structures like bunkers and tranches were designed in such discipline to keep them active round-the-clock with heavy armoury and made functional near to Line of Control (LOC) and Line of Actual Control (LAC) which oppose the effect of highly intensive blast waves. In such a manner, field testing with different Indian assault rifles i.e. INSAS (Indian Small Arms System), SIG 716i (US origin), and INSAS LMG (Indian Small Arms System-Light Machine Gun) was made from different ranges starting from 50mts to 300 mts extreme. Such structures were designed to protect the safety of soldiers from the bump of bullet effect. Structures designed are very strong and durable with opposition to high lateral load and visible surfacing. Construction material used for building plays a foremost role. The investigation is based on unique and advanced ideas in designing the defence structures. The investigation elaborates on the difference between conventional designing and the special designing of defence structures, as the advanced concept of polythene aggregates performs better than ordinary concrete.