Single-story Structures Research Articles

Lateral-torsional buckling investigation of multi-tiers eccentrically braced frames with shear link beam

Multi-tiered braced frames (MTBF) are a type of braced frames with two or more tiers of bracing or bracing panels between horizontal diaphragm levels or locations of out-of-plane support, along with a beam at every tier level. They are commonly used in tall single-story building structures when it is not practical to use single bracing members spanning from roof to foundation levels. Additionally, they find application in multistory buildings with tall story heights. In this paper, lateral-torsional buckling of beams in a new type of MTBF called multi-tiered eccentrically braced frames (MT-EBF) is evaluated. This structural system is not mentioned in any of the current code and seismic criteria have not been provided. The main different of this system with eccentrically brace frame is the lack of laterally supported in the intermediate beam. Also, in industrial buildings that need architectural openings, this system is more useful than concentrically braced frame. For this purpose, the seismic behavior of four different MT-EBF with one and two tiers, along with two different configurations for the connection of braces to the beams, is studied. In the first configuration, the braces are connected to the beam using a gusset plate, and in the second configuration, the braces are directly connected to the beam using full penetration groove weld. The results of the numerical study indicate that in the first configuration, lateral-torsional buckling occurs in the intermediate beams, and the connection of the gusset plate to the beams lacks the necessary stiffness to prevent lateral-torsional buckling. However, in the second configuration, lateral-torsional buckling of the intermediate beams is prevented, and the connection of the braces to the beams has the adequate stiffness to prevent lateral-torsional buckling.

Mechanical properties of on-site manufactured stabilised compressed earth blocks: an experimental investigation and proposed models

ABSTRACT The interest in earth construction is growing increasingly as society becomes more aware of the importance of sustainable building. A considerable number of investigations have been devoted to studying the mechanical properties of compressed earth blocks (CEBs). However, most of these studies were conducted in laboratory settings. Little focus has been directed at studying the performance of CEBs that use on-site soil and other local materials to construct small-scale housing at the same location. A total of 120 CEBs were manufactured on-site from four block mixes: coarse soil with and without Phragmites Australis (Phragmites) and fine soil with and without Phragmites. By comparing the results achieved with minimum strength requirements from different building codes, the dry compressive strengths of all four block mixes were deemed adequate for single-storey structures. The addition of Phragmites caused a slight increase in the compressive strength and a slight decrease in the flexural strength of the CEBs. A formula to estimate the flexural strength of the blocks given the compressive strength is proposed based on a database of test results from the literature and this investigation’s results. CEBs can create a sustainable building solution, especially in remote areas and Indigenous communities with limited access to conventional building materials.

Development of a BIM Platform for the Design of Single-Story Steel Structure Factories

Traditional design methods for single-story steel structure factories are characterized by low levels of digitalization and high error rates. To deal with these problems, a building information modeling (BIM) platform for the design of single-story steel structure factories was developed in this paper, which aimed to improve the design process for such structures. Firstly, the components of the factory were categorized, and the Revit API was employed to automate the generation of the BIM model. Load applications and combinations were then established using the Revit API, which relied on a set of predefined parameters. Secondly, this paper proposed the creation of a dedicated database for data exchange between BIM software and finite element analysis software. Additionally, the SAP2000 Open Application Programming Interface (OAPI) was employed for the automated construction and analysis of the SAP2000 structural model. Finally, the innovative use of Dynamo–Revit API hybrid programming allowed for the visualization of internal forces directly within the Revit environment, significantly diminishing the dependency on standalone FEA software. The application results obtained on a project demonstrated that the developed platform markedly improves the efficiency of design single-story steel structure factories and ensures the accuracy of the structural analysis. This confirms that the developed platform can transform the traditional design process by integrating advanced digital tools, thereby providing a novel approach to the design of single-story steel structure factories.

Refined self-attention mechanism based real-time structural response prediction method under seismic action

Accurate prediction of structural response under earthquake is of great significance for structural damage and performance evaluation. In order to improve the efficiency of structure time history response prediction, this paper proposes a novel SeisFormer model based on the self-attention mechanism and deep learning technology. Through autoregressive prediction, the SeisFormer can achieve real-time prediction of the response time histories of a large number of nodes in the structure under seismic action and can effectively solve the problem of data scarcity. Four case studies are performed to verify the accuracy and efficiency of the proposed methodology, including validation on datasets obtained from elastoplastic seismic analysis of a single-story structure, a three-story structure, and an eleven-story structure, and measured data of a shaking table test model. In addition, this paper further studies the prediction accuracy of the SeisFormer through ablation experiments and comparative experiments. The experimental results show that the SeisFormer can accurately predict the acceleration, velocity, and displacement time histories of numerous nodes in the structure. The prediction accuracy outperforms the LSTM model, and the prediction speed is 193–109,824 times faster than finite element method. Furthermore, with data augmentation through autoregressive prediction, the SeisFormer model can achieve efficient and accurate predictions when training data is exceptionally scarce, enabling engineering applications.

Effects of modeling assumptions on prediction of seismic demands of a single-story RC structure

This study investigates the seismic response of a single-story reinforced concrete (RC) structure subjected to strong ground motions. Effects of modeling assumptions used to idealize the reinforcement slip in beam-column joints and column footing are studied. For this purpose, the numerical model of a single-story, single-bay, three-dimensional asymmetric RC structure, tested on a shake table and its symmetric version, is analyzed. Two modeling approaches are considered to show the significance of rotation associated with the reinforcement slip. Bidirectional nonlinear time-history analyses are conducted using symmetric and asymmetric 3D models. In these analyses, 30 pairs of near-field ground motions, selected and scaled to match the target spectrum, are used. The findings indicate that the neglection of reinforcement slip in numerical model may result in an underestimation of almost 50% in story drift ratio demands.

Equivalent Lateral Forces for Design of Multistory Sliding Base Structures

The sliding base (SB) technique is an efficient and economical approach to mitigating seismic damage of low-rise buildings in rural areas. Based on the previous work on single-story SB structures, this study investigates the earthquake forces acting on multistory SB structures. Response history analyses of SB structures subjected to three-component earthquake excitations were performed. The computed results indicate that the increase in the number of stories tends to reduce the mean value of the peak base shear but has little influence on the coefficient of variation of the peak base shear. The peak story shears of a multistory SB structure subjected to an earthquake ground motion are reached at different time instants for different stories. The distributions of the equivalent lateral forces for SB structures with different story numbers follow the same trend, and the equivalent lateral forces tend to concentrate at the upper floors as the normalized peak ground acceleration and mass ratio increase. Simplified equations for computing the distribution of equivalent lateral forces were developed for design purposes.

Horizontal self-centering structural system in steel structures diaphragms

In this article, the benefits for the seismic behavior of a single-story steel structure fitted with a novel Horizontal Self-Centering Structural System (H-SCSS) between the Vertical Lateral Force Resisting Systems (VLFRS) and the floor diaphragm are investigated. A description is provided of the proposed self-centering system which connects the diaphragm to the vertical lateral force system. Nonlinear static, nonlinear cyclic quasi-static, and time history analysis were compared to explore the benefits, understand the limitations, and identify the controlling parameters in the behavior of a prototype special concentrically braced steel frame (SCBF-X, according to ASCE 7–16) with and without H-SCSS. In general, the following results were observed: reduction of residual drift, concentration of energy dissipation in the fuses, increase in the structure ductility, reduction of stresses and inelastic deformations in the vertical lateral resistance systems. These benefits have the potential to lead to reduce the weight of the structure.

Study on innovative residential buildings concept for economically weaker sections

Every day, more buildings are incorporating sustainable architectural principles, but it is crucial that these principles remain accessible to low-income families. The primary objective of this project is to design a sustainable residential building, specifically a single storey structure, to accommodate four individuals from the economically backward section of society. The proposed design emphasizes the use of environmentally friendly materials and strives to achieve high energy efficiency by considering the natural environment of the site and minimizing both operational and embodied energy. In order to enhance the indoor environment quality and minimize the negative impacts of cement and steel, this design prioritizes the surrounding natural environment. Additionally, a life cycle assessment was performed to determine the building’s design life. Key sustainable building parameters, such as daylighting and ventilation, have been incorporated into the design to reduce operational energy consumption. Furthermore, a cost analysis was conducted to compare the proposed design with conventional construction methods. The results indicated that the proposed design not only boasts a lower cost but also integrates the use of environmentally friendly materials, aligning with sustainable objectives.

Quasi-static model test and numerical simulation of a single-story double-span underground subway station

The model test method is crucial for studying the seismic performance of underground structures. Presently, model tests for the seismic response of underground structures are primarily performed with 1-g and N-g centrifuge shaking table. The 1-g shaking table model test is limited by the stress similarity in the soil-structure interaction system and cannot reproduce the seismic damage process and extent of the underground structure. The small table size of the N-g centrifuge model test makes it difficult to reflect the spatial effects of the seismic response of large underground structures. Seeking a large-scale model test method that can directly simulate the seismic damage process is essential for investigating the seismic performance of underground structures. Herein, based on the seismic response characteristics of underground structures, a quasi-static pushover test device applicable to underground structures was designed, and the corresponding tests and numerical model calculations were executed using the Daikai subway station as a prototype. Based on the macroscopic phenomena of structural damage development of the subway station in the test, the damage mechanism of the station structure was analyzed and compared with the numerical model. The strain amplitudes, displacements, and digital scatter strain color maps were analyzed to verify the reliability of the cyclic pushover loading test simulating the seismic performance level and damage process of the underground structure. Simultaneously, the rationality of the proposed quantification system for classifying the seismic performance level of single-story underground structures was verified.

一軸偏心した1層木質耐力壁構造における弾塑性捩れ振動の簡易評価法

Displacement mode including torsion when subjected to major earthquake is clearly related to strength balance of each frame while elastic torsional vibration is characterized by stiffness balance. In the previous research, we presented a displacement mode prediction method especially focusing on single-story timber structure having large strength eccentricity. The method is improved by taking the effect of plasticity of transverse walls and bi-axial input motion into account. Finally, necessary additional strength for seismic design of torsionally coupled structure is calculated and is related to eccentricity index. The accuracy of the evaluation method is demonstrated via numerous time history analyses.

A template design and automated parametric model for sustainable corbel dwellings with interlocking blocks

Existing approaches to sustainable dwellings often involve high-tech equipment and skilled workers, which are less accessible in low-resource settings. This research introduces a novel template design and automated parametric model for the design of corbel dwellings that can be built using standard equipment, local material, and lower-skilled workers. The template design is a modular, single-story dome-shaped structure transitioning from a square-base footprint to a circular roof zone using only five block types. Interlocking block features enable both aligned and offset dry stacking and reduce the use of mortar and formwork. The geometrically complex design is enabled by a parametric model that automatically synthesizes alternative designs and conducts preliminary structural analysis, including stability and FEA in real-time. The example context used is Morocco where the entire structure can be constructed using Compressed Earth Blocks. A range of dwellings are automatically generated using one set of blocks to explore the design space.

Geotechnical Seismic Isolation System Based on Rubber-Sand Mixtures for Rural Residence Buildings: Shaking Table Test

The anti-seismic problem of rural residential buildings is the weak link of seismic retrofitting in China. Recently, geotechnical seismic isolation (GSI) technology based on rubber-sand mixtures (GSI-RSM) using rubber-sand mixtures (RSM) between the structural foundation and the foundation soil has been proven to have the possibility of potential applications in rural residential buildings. Many theoretical studies exist on the effectiveness of seismic isolation of the GSI-RSM system, but few studies on either the seismic response test of model buildings placed on the RSM layer or the large-scale shaking table test exist. Therefore, this study considers a large shaking table test performed on a 1/4 single-story masonry structure model with and without a GSI-RSM system by selecting a standard input ground motion and varying input acceleration amplitudes. The test results show that the GSI-RSM system can reduce the seismic response of superstructures. The isolation effect of the GSI-RSM system is low in small earthquakes and increases with increasing earthquake magnitude. Overall, the RSM layer can filter part of the high-frequency components of the earthquake to transmit to the superstructure and consume more seismic energy by generating friction slip in the interaction with the structural foundation.

3D Evaluation of fine-scale normalised DSMs in urban settings

Humankind often needs to accurately model, identify and spatially quantify aboveground phenomena on the Earth’s surface for informed decision-making. Height data derived from digital elevation models (DEMs) is often used to achieve this. This study conducted a deterministic assessment of three normalised digital surface models (nDSMs) of different spatial resolutions, namely 2m, 4m and 12m, derived from VHR digital stereo aerial photography, tri-stereo Pléiades imagery and Tandem-X InSAR data, respectively. Covering a predominantly built-up area within a city landscape, the nDSMs were vertically and volumetrically compared to assess their quality and fit-for-use. In each case a consistent systematic evaluation was accomplished against a lidar derived reference surface at matching spatial resolutions (co-registered) using a semi-automated GIS routine. The relative height and volumetric errors were statistically analysed and described, including those computed individually over nine urban land cover/land use (LCLU) classes and several selected large buildings. Higher vertical accuracies were reported across single storey structures and areas with no to little or short vegetation, as apposed to substantially lower accuracies obtained over multi-levelled buildings and tall (dense) woody vegetation. Here significant underestimations of volumes exacerbated by lower spatial resolutions were also observed across each nDSM. Conversely, notable volume overestimations were found over predominantly grass-covered areas in especially the finer-scaled nDSMs. VHR elevation data is recommended to model and quantify aboveground elements spatially in 3D (e.g. buildings, earthworks and woody vegetation) in urban landscapes, but a sensitivity test beforehand remains critical to ensure more reliable outcomes for users and stakeholders alike.

Proper configuration of stiffness and strength centers in asymmetric single-story structures with semi-flexible diaphragms

While plan-asymmetric structures have more potential for torsional effects and diaphragm flexibility during seismic response, they had received less attention from this viewpoint in previous studies. In fact, due to the complex torsional-flexibility interaction of asymmetric structures with flexible diaphragms when subjected to seismic responses, evaluating the performance of these structures is more complicated. Therefore, there is not a general agreement as what configuration of centers (stiffness and strength centers) is the best one to limit seismic demands in such structures. Accordingly, there is a need to conduct extensive parametric studies to quantify the effects of structural asymmetry, diaphragm flexibility and earthquake intensity simultaneously, so that designers can be aware of the likely impact of diaphragm flexibility in asymmetric-plan structures. For this purpose, single-story models with different configurations of mass, stiffness, and strength centers and a wide range of diaphragm flexibility from fully rigid to quite flexible were studied. Since ground motion characteristics have a great impact on the behavior of these structures, the considered models were subjected to a set of seismic ground motion records and each record was scaled to eight different earthquake intensities. Then, the seismic behavior of these models was evaluated using different structural response parameters: structural rotation, story drifts of lateral load resisting elements, diaphragmś deformational modes and sensitivity of the structural seismic behavior to earthquake intensity. Finally, based on the obtained results, the proper configuration of stiffness and strength centers in asymmetric structures with flexible diaphragms has been proposed.

Optimization of Tuned Liquid Damper Including Different Liquids for Lateral Displacement Control of Single and Multi-Story Structures

This study focuses on tuned liquid dampers (TLDs) using liquids with different characteristics optimized with the adaptive harmony search algorithm (AHS). TLDs utilize the characteristic features of the liquid to absorb the dynamic forces entering the structure and benefit from the sloshing movement and the spring stiffness created by the liquid mass. TLDs have been optimized to investigate the effect of liquid characteristics on the control by analyzing various liquids. For optimization, the memory consideration ratio (HMCR) and fret width (FW) values were adapted from the classical harmony search (HS) algorithm parameters. The TLDs were used on three types of structure models, such as single-story, 10, and 40 stories. The contribution of the liquid characteristics to the damping performance was investigated by optimizing the minimum displacement under seismic excitation. According to the results, it was understood that the liquid density and kinematic viscosity do not affect single-story structures alone. However, two characteristic features should be evaluated together. As the structure mass increases, the viscosity and density become more prominent.

A New Approach to Symmetry Reliability: Combination of Forward and Inverse Reliability Principle and Its Application to Frame Structures and Bamboo Bridges

Reliability theory is the core basis of engineering design, mainly including forward reliability theory and inverse reliability theory. Forward reliability theory is used to obtain the reliability index using the known design parameters, that is, it is a mapping function that translates the design parameters to the reliability index. Inverse reliability theory is used to obtain the design parameters using the known reliability index, that is, it is a mapping function that translates the reliability index to the design parameters. In other words, forward reliability theory and inverse reliability theory together constitute a method of dual mapping, which is the specific application of symmetry theory in the reliability field. In this paper, a new inverse reliability analysis method is proposed, which can satisfy the requirements of the target reliability index while obtaining the design parameters, without additional calculation and verification of reliability. The method simplifies the reliability inverse problem to the problem of the nonlinear equation, which is solved by identifying the design parameters, and finally obtains the design parameters by iterating the reliability index for each design parameter to gradually approach the target reliability index. For high-dimension and complex problems, the Levenberg–Marquardt method is introduced to avoid the problem of sensitivity to initial values and iterative divergence when identifying the design parameters. The implicit limit state function problem is solved by the interactive operation between ANSYS software and MATLAB software using finite element theory. The accuracy of the proposed method in this paper is verified by several numerical examples, the applicability of the implicit limit state function is verified by a single-story frame structure, and the engineering applicability of the proposed method is demonstrated with a bamboo bridge.

Comparison between structural configurations designed by steel shear wall, moment resistant frame and X shape bracing systems

Nowadays, in order to increase construction of tall structures, the importance of choosing optimum systems, with a huge energy absorption capacity against wind and earthquake loads, has been widely considered. Since four decades ago, steel shear walls had been used as a stiff and high performance lateral system. This study is about the effect of concrete filled steel tubes (CFT) columns as vertical boundary elements of steel shear wall on seismic behavior of steel structures. Due to do this, three 10-storey steel structures, with similar plans and lateral load career systems of steel shear wall, coinciding X-bracing, and moderate steel frame were analyzed by means of non-linear, time-history method through SAP2000 software, and the results of roof displacement of them were compared with each other. Also after validating a two-storey, single-span frame sample with steel shear walls and CFT columns, 3 single-storey structures were analyzed by means of hysteresis and pushover, through ABAQUS software. The results of this study showed that a shear wall system presents suitable stiffness, resistance and ductility in comparison with other lateral bearing systems.

Experimental analysis of the metal roofed industrial building using nano-silica disbanded crude wax (NDCW)

The increased daytime temperature upsurges the energy need of the buildings for space cooling, particularly on days with strong sun exposure. The building's roof adds far more to this reason by allowing a big amount of heat to flow-in during the day. Additionally, single-storey structures with metal roofs allow for increased heat penetration, and so enhance the building's overall heat gain. They could do so by increasing the cooling load in order to achieve human comfort. The present work involved conducting an experiment to see whether a crude wax based Nano-silica (SiO2) Disbanded Phase Changing Material (NDCW) might be used to lower the internal temperature of a metal roofed single-story industrial structure effectively. This approach attempted to minimize the building's total cooling load, hence reducing the amount of conventional energy required. The research was conducted using a scaled-down model of the planned building. The trials were done in three phases: normal roof (Normal Roof) without crude wax, with crude wax in the roof (CW Roof), and with NDCW inside the roof (NDCW Roof). The NDCW was prepared by disbanding 1.0% volume of nano-silica within the crude wax. The findings from the investigations shown that encapsulating crude wax and NDCW under the metal roofing of a single-storey structure significantly lowered the exterior roof’s temperature, inner roof’s temperature, and further enhanced the thermal comfort of the indoor building space. With the assistance of crude wax and NDCW, the daytime mean internal space temperature was decreased by 5 °C and 6 °C, respectively. Further, the corresponding daytime peak was diminished by 10.5 °C and 12.5 °C with crude wax and NDCW, respectively.

Analysis of Dynamic p-y Curve Characteristics According to Mode Shape of Structure Using Shaking Table Tests

In the seismic design of pile foundations, a p-y curve representing the nonlinear behavior of the ground considering the dynamic load of the earthquake is required. Recently, p-y curve analyses reflecting the soil-structure interaction have been conducted, but studies on multilayer structures have not been investigated extensively. In this study, the p-y curve characteristics were analyzed, considering the influence of the ground-structure interaction based on the mode shape of the structure (no structure, single-story structure, and three-story structure) through shake table tests. It was found that (1) the bending moment and pile displacement increased with input acceleration, and (2) the maximum soil resistance and pile displacement occurred at the natural frequencies of each structure were observed. In addition, the bending moment, soil resistance, and p-y curve slope were higher in the single-story structure than in the three-story structure. The findings indicate that the seismic design simulated for a single-story structure is conservative.

Experimental study on annular cylindrical tuned liquid dampers for vibration control under different excitation angles

This work aims to experimentally show the effectiveness of annular cylindrical tuned liquid dampers (ACTLDs) on the classical tuned liquid column dampers (TLCDs) under the effect of inclined ground motion. For experimental measurements, a single-story model structure constituted by two plates at the top and bottom connected by four columns was constructed. Since the water length within the tuned liquid dampers (TLDs) is a very important parameter that affects the performance of the absorber, ACTLD and TLCD devices were designed such that their total water lengths be equal for comparison purposes. The modal characteristics of the model structure were determined by ambient vibration tests. The resonant frequency, head-loss coefficient, damping ratio, and water height-frequency diagram of ACTLD and TLCD devices were obtained experimentally through the shaking table tests. Then, the shaking table tests on the model structure with and without the absorbers under consideration were performed to obtain the acceleration and displacement time-histories and the damping ratio for the coupled system. In experimental tests, different excitation directions from 0 to 90 deg were considered. Results of the study show that ACTLDs are better than TLCDs at suppressing vibrations caused by ground motions acting on the structure at oblique angles.