Building Structures Research Articles

Review on Fragility Analysis of Building Structure in Seismic Prone Area

In general, using a steel bracing system is the most effective choice for enhancing the resistance of reinforced concrete frames to lateral loads. Steel bracing offers notable advantages over other methods, including greater strength and stiffness, cost-effectiveness, a smaller footprint, and minimal additional weight on existing structures. Both empirical and analytical fragility curves have been taken into account. Strengthening seismically deficient reinforced concrete frames with steel bracing systems is a practical solution for improving earthquake resilience. Nearly all structural analysis software, such as ETABS and SAP2000, supports linear and nonlinear static analysis for high-rise structures. Key parameters include fragility curves, the P-Δ effect, base shear, lateral displacement, axial force, and story drift, among others. The findings showed that bracing systems significantly reduce lateral displacement in frames. Fragility curves were developed based on peak ground acceleration (PGA) for various limit states—slight, moderate, major, and collapse-assuming a lognormal distribution. This study aims to develop analytical fragility curves for high-rise building structures.

Sub‐assemblage testing and fragility analysis of connections of continuous‐plasterboard suspended ceiling systems

AbstractPast earthquake reconnaissance reports highlighted extensive seismic damages to suspended ceiling components and connections, including instances of complete ceiling failures. The seismic qualification of these nonstructural elements typically requires comprehensive evaluation through full‐scale shake table testing. However, such experimental evaluation is ordinarily not possible for every change made in various components and connections of ceiling systems due to the cost and effort involved. A feasible alternative is to obtain the behavior of components and connections from sub‐assemblage testing and incorporate them in appropriate numerical ceiling models to derive mechanical responses for developing alternative or new installation schemes. This paper considers critical connections of three continuous‐plasterboard suspended ceiling systems that were evaluated using shake table‐generated motions. The connections were classified according to their attachment to typical floors and walls of building structures, and sub‐assemblage testing was conducted using both monotonic and cyclic displacement loading. The observed failure modes in each connection were detailed, and appropriate damage states were assigned as the basis for constructing connection fragility curves. The results of the sub‐assemblage testing were presented in terms of the hysteresis responses, envelope curves, nonlinear backbone curves, and cumulative energy dissipation curves. Additionally, multilinear models of the connections were derived by approximating nonlinear backbone curves’ initial‐ and post‐yield behaviors. These multilinear models were further idealized to derive three equivalent linearized models for simplified yet reasonably accurate results for linear structural analyses. Finally, fragility curves were derived for all connections, considering their cyclic displacement failure capacities.

Quantitative Estimation of Albedo and Tilt Angle Variation in Bifacial Perovskite Solar Cells.

Bifacial perovskite solar cells (Bi-PSCs) have attracted substantial attention within the photovoltaic (PV) community due to their potential for enhanced power generation, suitability for integration into building structures and applicability in multijunction PV systems. This study presents the fabrication of efficient Bi-PSCs and investigates their unique properties using various characterization techniques, including Lambertian reflection effects through tilt angle arrangements and bottom albedo illuminations. The control device achieved a maximum power conversion efficiency (PCE) of 17.46% under front-side 1 Sun AM1.5G illumination. A significant influence of ground Lambertian reflection is observed with tilt angle variations, resulting in an increase in PCE from 17.46% → 18.82% as the tilt angle reached 20°. Additionally, enhancing the rear-side albedo to 0.5 Sun yielded a maximum PCE of 26% with a bifaciality factor of ∼90% at a tilt angle of 20°. Consequently, the synergistic effect of 0.5 Sun albedo and a 20° angular light inclination led to the development of Bi-PSCs with an efficiency of 26.46%. SCAPS-1D simulations are further employed to validate the experimental Lambertian reflection effects. Moreover, the Bi-PSCs exhibited intrinsic self-encapsulation and chemical robustness (T80 for 2000 h in the N2 atmosphere). This study anticipates that cost-effective and highly efficient Bi-PSCs will emerge as a leading PV technology in both single-junction and tandem PV configurations for electricity generation in the near future.

The Effect of Steel Over Strength Ratio on Structure Behavior

Seismic design of steel building structures according to SNI 7860:2020 determining the necessary strength of structural members based on the expected yield stress, Ry.Fy, and the expected tensile stress, Rt.Fu. However, the values of Ry and Rt in SNI 7860:2020 are not yet based on the testing of steel products in Indonesia and are still based on the provisions in AISC 341-16. This research was conducted by collecting data on steel tensile test results to obtain the over-strength ratio and then modeling the steel frame building using the over-strength steel provisions of SNI 7860:2020 and based on the tensile test results to determine the difference in structural behavior. Based on the tensile test results, WF300 steel has a yield strength ratio (Ry) of 1.78, which is higher than the SNI specification of 1.5, and a tensile strength ratio (Rt) of 1.35, which is higher than the SNI specification of 1.2. Based on pushover analysis, the deviation value at the initial formation of the plastic hinge on Structure A1 (Ry=1.5) in the x-axis direction of 79.352 mm is smaller than Structure B1 (Ry=1.78) by 94.01 mm. This indicates that the plastic hinge of Structure A1 is formed earlier than Structure B1.

Nonstructure–structure interaction with respect to mass ratio: Numerical analysis and free vibration tests

The dynamic interactions between nonstructural components (NCs) and the main building structure cannot be neglected because the dynamic properties of the main structure are modified, particularly for heavy NCs. The mass ratio (MR) is a parameter that incorporates the nonstructure–structure interaction (NSI) between the NCs and main structure. In this study, to investigate the seismic interaction in terms of the MR, a four-story steel moment frame was constructed and free vibration tests were carried out. The equivalent mass of the NCs was connected to various floor levels, neglecting their stiffness and damping. The vibration mode and period of the steel frame were obtained numerically. At MR = 25 %, the period generally increased with increasing MR. The modal contribution factors in terms of the roof displacement and base shear were analyzed. The findings show that it would be safe to consider the 1st mode only when using the roof displacement, whereas more modes should be considered when the base shear is used. The experimental damping ratios correlated with the magnitude of the MR without a representative trend. The damping ratio generally increases with an increase in the number of floors hosting additional masses. The experimental period increased almost linearly with the MR irrespective of the number of floor-hosting masses. An equivalent single-degree-of-freedom model is developed to predict the frame period. The predicted periods generally matched the experimental results. The normalized height of the equivalent model and period ratio vary with the MR and are correlated with the number of floors hosting the mass. The results of this study will be beneficial for the seismic design of building structures with heavy NCs.

Study on the deterioration of mechanical properties of stainless steel S35657 exposed to overall stage of fire

Fires often have destructive effects on steel structures, putting the safety of building structures at serious risk. As a new austenite stainless steel, grade S35657, its in-fire and post-fire mechanical behavior has not been reported, which limits its application. In this paper, a total 68 stainless steel S35657 coupons were designed and tested, with 34 coupons used for in-fire tests and 34 for post-fire tests. The effects of heating temperatures, loading rates, and heating soaking times on the mechanical properties were investigated. The failure modes, as well as the stress-strain curves and mechanical properties, were acquired. Electron microscopy scanning analysis were also conducted on the coupons to study the fracture mechanisms at elevated temperatures. The test results showed a rapid decline in in-fire mechanical properties when the temperature exceeded 600 °C. The yield strength of the coupon at 1000 °C is only 9.1 % of that at room temperature. As the tensile rate increased, the strength of the coupon increased gradually. For post-fire coupons, there is no significant change in the mechanical properties of coupons at temperatures ranging from 20 °C to 900 °C. However, after reaching a temperature of 1000 °C, the coupon experienced a reduction in yield strength (up to 27.8 %) and an expansion in elongation (up to18.0 %), compared to the coupon at ambient temperature. This related to the change in grain size of the coupons after exposure to high temperatures. The heating soaking time has an insignificant effect on the post-fire mechanical properties of stainless steel S35657. Existing constitutive models in the literature cannot be well applied to stainless steel S35657, new constitutive models to predict the in-fire and post-fire mechanical properties have been established. Moreover, reduction factors for the key mechanical properties were compared with existing values, and new unified equations for stainless steel S35657 were proposed. Finally, a reliability analysis was performed to evaluate the proposed design rules, and it was deemed that the proposed design rules were reliable. The findings of this study will provide a reference for engineers in evaluating the in-fire and post-fire residual strength of stainless steel S35657, and offer guidance for fire resistance design and high-temperature repair reinforcement.

Spatial Assessment of Urban Heat Island (UHI) in Kütahya using Landsat-8 Satellite Data

The Urban Heat Island (UHI) effect refers to the phenomenon where urban areas experience significantly higher temperatures than their rural surroundings due to human activities and modifications, such as replacing natural land cover with impervious surfaces, reducing vegetation, and increasing heat-absorbing materials. Kütahya central district has a dense population and building layout, which contributes to the intense UHI. Geographic Information System (GIS) and its tools are widely used in assessing UHI in urban areas, providing insights for both researchers and local authorities. Landsat-8 images acquired on August 8, 2023 (Path: 179, Row: 33, Cloud Cover: 0%) were utilized to create the Urban Heat Island (UHI) map for the study area. Through spatial analysis using Landsat-8 data for Kütahya city center, six different classes were defined, with the UHI map created using land surface temperature values. The highest and lowest UHI values vary between 4.245°C and -3.457°C. It has been observed that the average UHI increases by 12% in areas lacking dense building structures, characterized by rock surfaces and limited green areas. Conversely, in areas with parks, forests, and sparse settlements, the UHI decreases by 10%. With this study, a comprehensive evaluation of UHI was conducted for Kütahya city center. While the results obtained are expected to be an important resource for researchers and local authorities, they are also anticipated to be beneficial in the fields of engineering geology, urban geology, and urban planning.

Design Method of a Novel Interface Connection Device for Multiscale Test Model Considering Multiparametric Similarity of Internal Forces

ABSTRACTThe multiscale model of building structures, as a balanced solution between accuracy and cost, has been widely used in the analysis of structural seismic performance. A reasonable interface connection method can accurately ensure load transfer and motion coordination between models of different scales. In this paper, a novel interface connection device and the corresponding design method for a multiscale test model of building structures were proposed, in which the upper structure with smaller sized components was replaced by a simplified story‐scale model, and the lower structure was adopted as a component‐scale model. The overall and local equations of motion for this multiscale model were established. For the interface connection between different scale models, a design method considering multiparametric similarity of shear force, axial force, and bending moment was proposed. In this method, the internal nodes at the interface of the component scale model were decomposed, and the coupling relationship of internal force between two adjacent nodes was established. The axial force of each node was decoupled into the interstory shear force and bending moment provided together. Additionally, the overturning moment is provided by adding the overlapping domain. According to the equilibrium relationships of the nodes at the interface, the corresponding transfer matrix was provided, and the design method of the interface connection device was proposed. The accuracy and feasibility of the method were validated by static and shaking table tests on a frame structure.

Experimental Study on Horizontal Resistance Parameter of Gravelly Soil Considering Slope Gradient Factor

Horizontal resistance can be significantly different for gravelly soil slope sites with different gradients. The impact of slope gradient on the horizontal resistance of soil based on a three-dimensional physical simulation test has been investigated, and the displacement of the pile top and soil pressure for four piles under various gradients (slope gradient 0–45°) was analyzed. The research reveals that ① The soil resistance exhibits a linear increase stage, non-linear steep increase stage, and gradually stabilizing stage with the increase in load. ② The ultimate soil resistance is significantly affected by depth and displacement, and hyperbolic variation characteristics related to the displacement stage. It has a slope weakening effect, and the steeper the slope gradient, the lower the ultimate soil resistance of the pile sides, which effect is negligible when the depth exceeds 0.6–0.7 times that of the pile buried depth. ③ Based on the characteristics of horizontal ultimate resistance-displacement-depth variation in soil, a gradient factor, which is only related to the slope gradient, was used to describe the impact of gradient on the soil resistance modulus (kini) and ultimate resistance (pu). kini is reduced close to the ground surface and gradually increases with depth until it becomes equal to the value of level ground. The ratio between pu in slope ground and level ground was determined for slope angles. The above horizontal resistance parameters were expressed as a function based on the test data to calculate the lateral ultimate bearing capacity of gravelly soil considering the slope gradient factor. The research results developed the theory of foundation design for building structures, promoting the reliability evaluation of pile soil systems towards a more scientific and rigorous direction.

HRTBDA: a network for post-disaster building damage assessment based on remote sensing images

ABSTRACT Efficient building damage assessment after disasters is vital for emergency response and loss evaluation, but the task is complicated by diverse building structures and complex environments. Traditional methods using Convolutional Neural Networks (CNNs) struggle to capture global contextual features, limiting damage categorization accuracy. To address this, we introduce the High-Resolution Transformer Architecture for Building Damage Assessment (HRTBDA), which enhances multi-scale feature extraction. A Cross-Attention-Based Spatial Fusion (CSF) module is proposed to utilize the attention mechanism, improving the model’s ability to identify detailed associations in damaged buildings. Additionally, we propose a deep convolution network matching optimization strategy that integrates a multilayer perceptron and expands the receptive field, enhancing global feature perception. HRTBDA’s performance was evaluated on two public datasets and compared with five recent frameworks. The model achieved an F1-score of 86.0% in building localization and 78.4% in damage assessment, with a 4.8% improvement in detecting minor damages. These results demonstrate HRTBDA’s potential for improving building damage assessment and highlight its significant advancements over existing methods.

Experimental and numerical investigations on flexural behavior of apex joints in aluminum alloy portal frames

Aluminum alloy portal frames (AAPFs) find extensive applications in lightweight and temporary structures owing to their light weight, excellent corrosion resistance, and ease of installation and disassembly. Existing design equations for cold-formed steel portal frame (CFSPF) apex joints are not applicable to AAPF apex joints due to significant differences in structural configuration. Therefore, dedicated research is needed to develop design guidelines for AAPF apex joints. Consequently, this paper conducts experimental and numerical investigations on flexural behavior of AAPF apex joints. Initially, bending tests are conducted on three AAPF apex joints, revealing failure modes including clamping plate buckling and beam failure. The flexural behavior of apex joints throughout the entire process is analyzed based on moment-rotation curves and moment-strain curves. Subsequently, finite element (FE) models are established and validated by comparing the FE results with the experimental results. Following this validation, parameter analysis is conducted considering the influence of beam cross-sectional dimensions, clamping plate dimensions, bolt dimensions, and layout. Finally, based on theoretical and numerical investigation, the calculation equation for the flexural capacity of AAPF joints is derived, offering valuable reference for engineering design.

Semi-active vibration control via a magnetorheological damper and active disturbance rejection control

This work provides an alternative for the semi-active vibration control problem via state feedback plus an active disturbance rejection control (K-ADRC) for a multistory building structure equipped with one magnetorheological damper (MRD) located between the ground and the first story. This control law introduces a disturbance observer (DOB) to estimate the total disturbance in real time, produced by the earthquake perturbation, unmodeled dynamics, and parametric uncertainties, and then cancel their effect using a part of the control signal. Moreover, using a diffeomorphism, the K-ADRC provides a proportional derivative (PD) controller designed to improve internal stability. A prominent feature of the active disturbance rejection control (ADRC) algorithm is that the value of the DOB gain is selected according to the system bandwidth. The stability of the system is verified via Lyapunov analysis. Moreover, the building structure model and the MRD are accomplished by incorporating a nonlinearity state that represents the hysteresis effect to perform real behavior in addition to assuming that acceleration is the only available measurement of building structures. Thus, integral filters are provided based on the appropriate cut-off frequency to estimate displacement and velocity, avoiding bias, offset, and phase shifts. Experimental results from a reduced-scale two-story building prototype demonstrate that the proposed K-ADRC is promising for real applications, and it has better performance than the state feedback (K) and the linear quadratic regulator (LQR) control techniques.

Application of pole allocation to optimize passive viscous dampers represented by the Maxwell model

The Maxwell model is used to understand the realistic effectiveness of vibration reduction in the building structures. The model consists of a dashpot and spring in series. The dashpot and spring represent a viscous damper and joint between the damper and the structural frame, respectively. However, few studies have investigated the optimal damper capacity and the corresponding spring stiffness in the practical parameter ranges. Additionally, the optimal damper derived using the fixed-point theory has no relationships with that derived via pole allocation. Therefore, in this study, to examine the effects of the joint spring, the pole allocation method was used to design a structural system wherein the Maxwell model was incorporated into a single-degree-of-freedom damped model. We introduced a closed-form expression, which explicitly described the relationships between the target structural damping ratio, damper capacity, and joint spring. The Maxwell model constrained the control effectiveness using damper parameters and simultaneously suggested an optimal and realistic joint spring for the damper. Pole allocation was also applied to a multi-degree-of-freedom (M-DOF) damped structural system employing multiple Maxwell models. The newly proposed optimized joint spring could easily control the additional damping effect on the M-DOF system. The Maxwell model can be optimized almost manually. The scheme is more useful in the preliminary design stage than the previous numerical optimizations. This study extended the mathematical equation governing the building vibrations to the Maxwell model. The extended equation served as a unified description for considering structural passive control.

Review of Performance and Applications of Common Fiber-Reinforced Concrete

Since the advent of concrete materials, it has been widely used in building structures due to its advantages such as good compressive performance, durability, and ease of sourcing. In the 1970s, to further enhance the performance of concrete, fiber materials were proposed for incorporation into concrete to address its shortcomings of poor ductility and insufficient tensile strength. This paper reviews the recent research status, advantages, and mechanical performance of fiber-reinforced concrete, and explores the future development trends of its application in building structures.

A Review of Seismic Optimization Design of Building Structures with Uniform Response

Earthquakes threaten human survival with powerful destructive power, and the performance of buildings in earthquakes is crucial. The seismic design of traditional building structures has the limitations of non-uniform response to displacement and acceleration, which can easily lead to partial damage to the building, unreasonable structure and difficulty in post-earthquake repair, which seriously affects the comfort and safety of the building. It is emphasized that improving the seismic safety of buildings is not only an inevitable requirement to ensure the safety of people's lives, but also to meet people's needs for continuous improvement of building comfort. The review shows that it is of great practical significance to study the seismic optimization design method of building structures with uniform response, which provides an important reference direction for the future design of building structures.

Low-Cost Thermal Point Clouds of Indoor Environments

Abstract. The integration of low-cost thermal sensors with Apple Smart Devices supports the generation of 3D point clouds that include temperature indicators. This generates a new perspective for the study of buildings, allowing for fast and reliable examination of physical building structures. To the best of our knowledge, this study is the first to demonstrate the use of affordable sensors for 3D thermal point cloud generation. The study involved capturing data from the LiDAR and thermal sensors, followed by an extrinsic calibration process to align the datasets. Subsequently, the point cloud was segmented based on different acquisition poses of the device and finally, the thermal data was projected onto the 3D model, integrating temperature information with spatial coordinates. Our results demonstrate the effectiveness of the approach for three-dimensional point cloud generation in indoor environments, highlighting significant thermal variations and enabling thermal mapping of building structures. Furthermore, our findings underscore the feasibility of employing low-cost sensors for generating detailed thermal models, opening possibilities for widespread adoption in various building analysis applications. This approach provides a comprehensive and cost-effective solution for building monitoring, democratizing access to advanced evaluation tools.

Evaluating the effectiveness of duplex corrosion protection systems applied to steel components of building structures

Evaluating the effectiveness of duplex corrosion protection systems applied to steel components of building structures

Spatial-temporal Data Model for Indoor Fire Response Considering Multi-Factors

Abstract. The complexity of high-rise building structures and functions significantly increases the challenges in emergency responses to indoor fire incidents. This complexity is due to multiple factors that must be evaluated for decision-making within the fire scenario, such as the entities within the building, the status of environment, and the actions of people. An effective and precise indoor fire emergency management model should fully take into consideration of multiple factors, aiming to ensure the safety and effectiveness of emergency response action.This paper proposes a spatial-temporal data model to integrate the entity-status-action, for designing the most suitable action strategies in various environmental status by considering all related entities in the indoor fire scenario. Firstly, a list of factors is designed to represent the scenario features including spatial location, semantic description, attribute characteristics, geometric form, evolutionary process, and the relationships among objects. Then, employs an ontology-based descriptive method to integrate multi-dimensions and effectively represents the interrelations among entities, actions, and environmental status within the context of an indoor fire scenario. These environmental status considered in the model focus on the supporting path-planning during execution of direct response actions. Finally, a set of path-planning rules has been developed to infer a series of environmental status supporting to formulate the optimal evacuation strategy to minimize the risk of evacuation failure. The case study shows that the proposed model is effective in unified expression for multitude of factors associated with emergency response in indoor fire scenario and supporting the decision-making of the emergency response actions.

Structural damage detection based on transmissibility functions with unsupervised domain adaptation

Deep learning (DL) has been used for structural damage detection by training neural network models with a large amount of data. These trained models perform well when the test samples are from the data with an identical distribution of the training data. The distributions are always different due to numerical modelling errors and operational environmental varieties, and the data for damage scenarios is difficult to be obtained in practice. A novel method based on the joint maximum discrepancy and adversarial discriminative domain adaptation (JMDAD) for structural damage detection without labelled measurement data has been developed to address the above issues. To reduce the influence of external excitations in practice, the transmissibility function of measured structural responses is used for structural damage detection. The proposed network includes a feature generator, two classifiers and one discriminator. Firstly, the feature generator and domain discriminator are to extract features and merge their distributions at the domain level to overcome the issue of insufficient data from the target real structure. Secondly, the generator and two classifiers are optimised to align their distributions at the class level using the classification discrepancy between the two classifiers. As a result, the damage-sensitive features are extracted and aligned to eliminate modelling errors and operational environmental varieties between the source and target structures. Three case studies have been conducted in this paper, e.g., one case between two building structures with different storeys, another case between the numerical and experimental structures subjected to random and earthquake excitations and the application of Canton Tower. The results show that the proposed method is much robust to the measurement noise and operational environment and the structural damage is identified accurately without labelled measurement data from the target structure in operational environments.

THERMAL ADAPTIVE ARCHITECTURE: INTERPLAY BETWEEN ARCHITECTURE AND CLIMATE

The concept of architecture as a form of shelter, integral to both classical and contemporary discourse emphasizes the interplay between building structures and their climatic contexts. Vitruvius early observations underscore the importance of understanding how buildings act as barriers and responsive filters to their environments thereby shaping human activities. This paper explores the multi-faceted roles of buildings-functional, social, symbolic, artistic and their interconnections with thermal performance. While the adaptability of buildings to thermal conditions is well recognized, the impact of fluctuating economic factors such as energy prices, and the unpredictability of space usage add layers of complexity to thermal performance assessments. The research highlights the gap between theoretical knowledge and practical application in achieving optimal thermal conditions. By examining the integration of precise thermal techniques into building design this study aims to bridge these gaps and propose strategies for designing climate-sensitive architecture. The focus is on achieving comfortable and healthy living environments while ensuring cost-effective resource use. This approach advocates for a refined understanding of thermal response and its application in the design-build-occupy process ultimately contributing to more efficient and adaptive building practices.