Buildings

32 pages, 5867 KB

Open AccessArticle

Proposing Novel Symbolic Regression-Based Equations for Predicting the Shear Capacity of Polypropylene-Fiber-Reinforced Concrete (PFRC) Beams Without Transverse Reinforcement

by Hasan Cem Akkaya, Kadir Sengun, Sema Alacali and Abdullah Nigdelioglu

Buildings 2026, 16(18), 3749; https://doi.org/10.3390/buildings16183749 (registering DOI) - 20 Sep 2026

Abstract

Predicting the shear strength of polypropylene and macro-synthetic fiber-reinforced concrete (PFRC) beams remains challenging because many available formulations were originally developed for conventional reinforced concrete or steel-fiber-reinforced concrete. This study develops practical and explicit symbolic equations for estimating the shear strength of PFRC [...] Read more.

Predicting the shear strength of polypropylene and macro-synthetic fiber-reinforced concrete (PFRC) beams remains challenging because many available formulations were originally developed for conventional reinforced concrete or steel-fiber-reinforced concrete. This study develops practical and explicit symbolic equations for estimating the shear strength of PFRC beams without transverse reinforcement. A dedicated database comprising 98 shear-critical PFRC beam specimens was assembled using clearly defined inclusion and exclusion criteria. Seven predictors representing beam geometry, concrete strength, longitudinal reinforcement, and fiber properties were employed. Gene Expression Programming (GEP) and Multi-Expression Programming (MEP) were used to derive explicit mathematical equations, which were evaluated using a hold-out testing subset and compared under consistent data conditions with six benchmark machine learning algorithms and twenty existing shear strength formulations. Unlike previous studies that generally focused on individual prediction approaches or specific classes of fiber-reinforced concrete, the present study combines a PFRC-specific database, two explicit symbolic regression methods, comprehensive benchmarking, and SHAP-based model interpretation within a unified framework. The proposed MEP equation achieved the best testing performance, with a coefficient of determination (R²) of 0.976 and a root-mean-square error (RMSE) of 15.75 kN. The corresponding mean absolute percentage error (MAPE) and coefficient of variation (COV) were 10.55% and 0.143, respectively. The GEP equation also demonstrated satisfactory predictive performance, with an R² of 0.965 and a MAPE of 18.16%. Among the benchmark machine learning algorithms, CatBoost achieved the best testing performance, with an R² of 0.968, but was outperformed by the MEP equation. The MEP equation also improved the highest R² among the twenty existing formulations from 0.883 to 0.976 and reduced the lowest MAPE among the existing formulations from 25.81% to 10.55%. Shapley additive explanations (SHAP) analysis indicated that beam width, shear span-to-effective depth ratio, and effective depth were the most influential variables governing the predictions of the MEP equation. Within the limits of the assembled database, the proposed MEP equation provides an accurate, transparent, and directly applicable approach for estimating the shear strength of PFRC beams without transverse reinforcement. Full article

(This article belongs to the Section Building Structures)

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23 pages, 3215 KB

Open AccessArticle

A CNN-PatchTST Hybrid Deep Learning Model for Multi-Target Multi-Step Attitude Prediction of Shield Machines in Small-Radius Curves

by Jinyan Liu, Tingyuan Wang, Lina Zhu, Li Kou and Zhiyong Yang

Buildings 2026, 16(18), 3748; https://doi.org/10.3390/buildings16183748 (registering DOI) - 20 Sep 2026

Abstract

Small-radius curved tunneling makes shield machine attitude control especially difficult. Intensified soil-machine interaction under these conditions creates a high risk of snakelike motion, which can compromise both construction safety and segment assembly quality. Accurate advance prediction of attitude parameters is therefore critical for [...] Read more.

Small-radius curved tunneling makes shield machine attitude control especially difficult. Intensified soil-machine interaction under these conditions creates a high risk of snakelike motion, which can compromise both construction safety and segment assembly quality. Accurate advance prediction of attitude parameters is therefore critical for timely course correction. We propose CNN-PatchTST, a hybrid deep learning model that integrates four complementary components. A convolutional neural network (CNN) extracts local temporal features. A PatchTST-based Transformer encoder applies global self-attention over long sequences. A direct mapping branch produces short-range inertial estimates, and a gated fusion layer performs adaptive signal integration. Operating as a unified architecture, the model simultaneously predicts all 12 key attitude parameters five steps ahead, providing operators with roughly five minutes of advance warning. Validated on construction data from the Fangbai Intercity Railway (Guangzhou Metro, minimum curve radius 350 m), CNN-PatchTST achieves a mean coefficient of determination (R²) of 0.992 across all 12 attitude parameters under three independent random seeds. Mean absolute errors (MAE) for the front and rear shield azimuths reach 0.578° and 0.430°, respectively. A pure-inertia baseline (using only historical attitude values) attains R² = 0.988, yet its azimuth MAE is 4.3 times higher than that of the full model. This result confirms that modeling control parameters is essential for accurate angular prediction. SHAP-based sensitivity analysis yields three further insights. First, historical attitude parameters account for approximately 97% of total feature importance. Second, the four most recent steps contribute over 50% of predictive power. Third, a lagged predictive association of roughly 3–4 min is observed between thrust jack pressure differentials and shield tail deviation response, suggesting a potential lagged association that warrants further causal validation. Collectively, these findings demonstrate that CNN-PatchTST delivers accurate and interpretable multi-step attitude predictions, establishing it as a practical tool for on-site guidance during small-radius shield tunneling. Full article

(This article belongs to the Section Construction Management, and Computers & Digitization)

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20 pages, 23637 KB

Open AccessArticle

Integrating the SBE–SD Method and Eye-Tracking Analysis for Evaluating Visual Experience in Traditional Village Heritage Landscapes

by Jianfu Chen, Qingqian Ning, An Yan, Yuxin Zhang, Hiroatsu Fukuda and Jie Zhong

Buildings 2026, 16(18), 3747; https://doi.org/10.3390/buildings16183747 (registering DOI) - 20 Sep 2026

Abstract

Rapid urbanization has posed significant challenges to the conservation and sustainable management of heritage landscapes. This study integrates the Scenic Beauty Estimation–Semantic Differential (SBE–SD) method with eye-tracking (ET) analysis to establish a subjective–objective framework for evaluating visual experiences in heritage landscapes, using the [...] Read more.

Rapid urbanization has posed significant challenges to the conservation and sustainable management of heritage landscapes. This study integrates the Scenic Beauty Estimation–Semantic Differential (SBE–SD) method with eye-tracking (ET) analysis to establish a subjective–objective framework for evaluating visual experiences in heritage landscapes, using the traditional villages of Hongcun and Xidi in Anhui Province, China, as case studies. A total of 117 participants completed the eye-tracking experiment, while 374 respondents with varied demographic and prior-visitation backgrounds participated in the SBE–SD questionnaire survey based on 28 representative landscape photographs. The results indicate that different landscape types exhibit distinct eye-tracking characteristics, with visual attention primarily concentrated on dominant architectural structures and visually salient landscape elements. Significant associations were identified between subjective visual quality evaluations and ET indicators, particularly fixation frequency (FF) and proportion of fixation duration (PFD). Associations were also observed between landscape perception dimensions and visual attention metrics, highlighting the relationship between perceived landscape characteristics and gaze behavior. The correspondence between ET results and SBE–SD evaluations supports the value of integrating subjective and objective approaches in heritage landscape assessment. Overall, the findings demonstrate the potential of eye-tracking as a complementary quantitative approach for understanding the visual quality of traditional village landscapes and provide practical implications for heritage conservation and landscape planning. Full article

(This article belongs to the Section Architectural Design, Urban Science, and Real Estate)

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32 pages, 40086 KB

Open AccessArticle

Improving Acoustic Performance While Preserving Visual Connectivity in Small-Scale Industrial Buildings: An Integrated Acoustic Design Methodology

by Mustafa İnce and Gülşen Akın Güler

Buildings 2026, 16(18), 3746; https://doi.org/10.3390/buildings16183746 (registering DOI) - 20 Sep 2026

Abstract

Small-scale industrial buildings commonly accommodate production areas and office units within the same building, where visual connectivity between these spaces is required to facilitate the monitoring and supervision of production processes. However, this functional requirement may increase airborne noise transmission from production areas [...] Read more.

Small-scale industrial buildings commonly accommodate production areas and office units within the same building, where visual connectivity between these spaces is required to facilitate the monitoring and supervision of production processes. However, this functional requirement may increase airborne noise transmission from production areas to adjacent office spaces, thereby adversely affecting acoustic comfort. This study proposes an integrated acoustic design approach to improve the acoustic performance of small-scale industrial buildings while preserving the required visual connectivity. A woodworking workshop and its adjacent office unit in the Design and Application Laboratory Building at Eskişehir Technical University were selected as a case study. Existing acoustic conditions were determined through in-situ noise measurements. The airborne sound insulation performance of individual building elements was evaluated using Prediction Sound Insulation (INSUL 6.2), while room-scale acoustic performance, including flanking sound transmission, was assessed using Kalksandstein (KS 8.03). The results identified the aluminum-framed glazed partition system as the dominant airborne sound transmission path between the workshop and the office. Following the numerical evaluation of the proposed design modifications, the DnT,A values were predicted to increase from approximately 33 dB to 57 dB, thereby exceeding the Class D acoustic performance criterion specified in the Turkish Regulation on the Protection of Buildings Against Noise (BGKKHY) for existing buildings. The results demonstrate that effective acoustic retrofit cannot be achieved by considering individual building elements alone, but requires the integrated evaluation of spatial organization, critical transmission paths, and receiver conditions. The proposed approach provides a practical framework for the acoustic design and retrofit of small-scale industrial buildings where visual supervision must be maintained. Full article

(This article belongs to the Section Architectural Design, Urban Science, and Real Estate)

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27 pages, 11851 KB

Open AccessArticle

Spatial Morphology and Thermal–Response Relationships During Winter Brisk Walking on a Coastal Promenade: A Field Study in Qingdao

by Yang Zhao, Linzhen Wei, Xingtian Wang, Qi Shen, Chenyang Shi, Huaiyu Yang and Han Li

Buildings 2026, 16(18), 3745; https://doi.org/10.3390/buildings16183745 (registering DOI) - 20 Sep 2026

Abstract

Coastal promenades support outdoor physical activity, yet how spatial morphology relates to thermal–response patterns during winter exercise remains unclear. This study examined physiological, cognitive, and psychological responses during standardized brisk walking at three coastal promenade locations in Qingdao, China. Sixteen healthy young adults [...] Read more.

Coastal promenades support outdoor physical activity, yet how spatial morphology relates to thermal–response patterns during winter exercise remains unclear. This study examined physiological, cognitive, and psychological responses during standardized brisk walking at three coastal promenade locations in Qingdao, China. Sixteen healthy young adults completed the same protocol at all locations. Air temperature, relative humidity, wind speed, spatial characteristics, and multidimensional human responses were analyzed using linear mixed models. Linear mixed models identified an enclosure ratio × air temperature interaction for mind–body connection: the temperature–mind–body connection relationship was more negative in the semi-enclosed condition than in the open conditions, indicating greater temperature sensitivity in the semi-enclosed setting. Other spatial–thermal and thermal/individual associations across physiological, cognitive, affective, exercise-related, and thermal-perceptual outcomes were exploratory or response-specific. Together, these findings characterize winter coastal walking as a multidimensional human–environment experience. They also motivate future design tests that combine spatial diversity with opportunities for users to choose between exposure and localized protection. Full article

(This article belongs to the Special Issue Advances in Urban Heat Island and Outdoor Thermal Comfort)

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25 pages, 1879 KB

Open AccessArticle

Audit-Aware SSDI-MoE Framework for Periodic Health Assessment of Centrifugal Chillers in Existing Buildings

by Hongyu Guo and Jia Wang

Buildings 2026, 16(18), 3744; https://doi.org/10.3390/buildings16183744 (registering DOI) - 20 Sep 2026

Abstract

The large stock of existing buildings creates demand for chiller assessment during energy retrofit and operation. However, many methods assume access to water flow, separately metered chiller power, and real-time cooling capacity. These measurements are often unavailable in existing plants, preventing online COP [...] Read more.

The large stock of existing buildings creates demand for chiller assessment during energy retrofit and operation. However, many methods assume access to water flow, separately metered chiller power, and real-time cooling capacity. These measurements are often unavailable in existing plants, preventing online COP calculation. Four water-side temperatures, two refrigerant pressures (4T2P), and a load-related variable such as compressor current are more commonly obtainable. This study develops an audit-aware sparse-sensor degradation index mixture-of-experts framework (SSDI-MoE) for periodic assessment under this measurement boundary. The framework compares a diagnostic period with a load-matched reference, converts five thermodynamic indicators into dimensionless ratios, and combines seven linear experts through a logistic gate. It estimates baseline-relative COP degradation while reporting load coverage, input validity, and disagreement among expert predictions. In file-separated validation using ASHRAE RP-1043 data, SSDI-MoE achieved an MAE of 0.0444 and an R² of 0.8984. Although tree ensembles achieve lower point-prediction errors, SSDI-MoE additionally reports the individual expert predictions and their disagreement. This information is useful for engineering reviews because it helps identify cases that warrant further inspection. An anonymized two-chiller field case illustrated monthly trend reporting from routine low-frequency records. The framework provides a preliminary screening approach for maintenance reviews when complete chiller metering is unavailable. Full article

(This article belongs to the Section Building Energy, Physics, Environment, and Systems)

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25 pages, 20394 KB

Open AccessArticle

Multi-Objective Capacity Configuration of PV-Energy Storage Systems in Low-Carbon Buildings with Electric Vehicles: A Bi-Level Optimization Approach

by Yifan Zhang, Taobin Wang, Lili Liu, Wenqian Yin, Jilei Ye and Yuping Wu

Buildings 2026, 16(18), 3743; https://doi.org/10.3390/buildings16183743 (registering DOI) - 20 Sep 2026

Abstract

To support low-carbon smart buildings, this study proposes a multi-objective capacity optimization method for PV-energy storage systems considering the flexibility potential of orderly electric vehicle (EV) charging loads. First, an orderly EV charging model based on price-guided charging quantifies the flexibility potential of [...] Read more.

To support low-carbon smart buildings, this study proposes a multi-objective capacity optimization method for PV-energy storage systems considering the flexibility potential of orderly electric vehicle (EV) charging loads. First, an orderly EV charging model based on price-guided charging quantifies the flexibility potential of EV charging loads. Then, a bi-level multi-objective capacity configuration model is proposed. In the upper level, the building operator minimizes both economic and carbon emission costs, jointly optimizing PV-energy storage capacity configuration and EV charging prices. In the lower level, EV users optimize their charging schedules to minimize their charging costs in response to the charging prices. To solve this bi-level multi-objective problem, the two objectives are normalized and weighted into a single-objective function, and then a heuristic solution method based on a genetic algorithm is developed. Case study results show that the proposed mode reduces building economic cost and electricity-related carbon emissions, demonstrating the benefits of incorporating carbon emissions into demand-side optimization under the “dual-carbon” targets. Full article

(This article belongs to the Section Building Energy, Physics, Environment, and Systems)

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29 pages, 1142 KB

Open AccessReview

Digital Twin Empowering Whole-Lifecycle Governance of Urban Infrastructure: A Review of Technological Embedding, Organizational Change, and Institutional Reconstruction

by Xiansheng Chen, Sha Liu, Yang Zhao, Changxu Zheng and Yaping Zhang

Buildings 2026, 16(18), 3742; https://doi.org/10.3390/buildings16183742 (registering DOI) - 20 Sep 2026

Abstract

As a frontier direction of engineering informatics, Digital Twin technology offers new technical possibilities for the whole-lifecycle governance of urban infrastructure. However, existing research mostly treats Digital Twin as a pure engineering system optimization tool, neglecting its governance attributes as a “Socio-technical System.” [...] Read more.

As a frontier direction of engineering informatics, Digital Twin technology offers new technical possibilities for the whole-lifecycle governance of urban infrastructure. However, existing research mostly treats Digital Twin as a pure engineering system optimization tool, neglecting its governance attributes as a “Socio-technical System.” Based on the systematic literature review method, this paper retrieves relevant literature from databases such as Web of Science, Scopus, and CNKI between 2010 and 2025; systematically reviews the application evolution of Digital Twin technology in urban infrastructure across the planning, construction, operation and maintenance, and decommissioning stages from the three dimensions of technological embedding, organizational change, and institutional reconstruction; reveals the transmission mechanism through which technological capabilities are transformed into governance effectiveness via organizational mediation; identifies key existing research limitations in current research regarding data governance, cross-sector collaboration, and institutional adaptation; and proposes an integrative three-dimensional “Technological Embedding—Organizational Change—Institutional Reconstruction” analytical framework. This study finds that the core challenge of Digital Twin governance lies in coordinating the structural tension between technological centralization and governance decentralization; future research needs to transcend technological determinism, situate Digital Twin within a broader socio-technical system context, and achieve the substantive transformation from “technology empowerment” to “governance effectiveness.” Full article

(This article belongs to the Special Issue Engineering Informatics for Intelligent Lifecycle Management in the Built Environment)

36 pages, 30453 KB

Open AccessReview

Advances in Vibration Research on Concrete Mix: Bibliometric Analysis and Hotspot Discussion

by Xingjun Liu, Jiang Guo, Mengdi Zhang, Qiuyi Wang, Yinuo Yin, Junxia Wang and Jiajie Li

Buildings 2026, 16(18), 3741; https://doi.org/10.3390/buildings16183741 (registering DOI) - 20 Sep 2026

Abstract

Research on the vibration of concrete mix is ushering in a critical opportunity for theoretical breakthroughs and construction innovations. This review aims to provide a systematic, data-driven overview of the research landscape of concrete mix vibration, with particular emphasis on identifying how existing [...] Read more.

Research on the vibration of concrete mix is ushering in a critical opportunity for theoretical breakthroughs and construction innovations. This review aims to provide a systematic, data-driven overview of the research landscape of concrete mix vibration, with particular emphasis on identifying how existing knowledge can support real-time vibration quality control and the development of intelligent vibration systems for construction sites. To achieve this, this review conducts a bibliometric analysis of the research on concrete mix vibration using VOSviewer analysis software. The analysis reveals that this research field is undergoing the surge stage since 2022. The major research countries include China, the United States, Japan, and South Korea. Among them, 47.9% of global publications and 66.7% of global major research organizations in this field originate from China. However, the cooperative relationships among organizations still need to be improved. The research hotspots in this field can be subdivided into the following: research on the vibration mechanism of concrete mix, research on the compactness of vibrated concrete mix, and research on intelligent vibration technology for concrete mix. This review further focuses on in-depth discussions of the above research hotspots, systematically combs through existing research achievements, and identifies the key issues that urgently need to be addressed. From a practical perspective, this review suggests that the precise perception of vibration parameters, visual recognition of surface rheological states, and energy-based methods collectively offer promising pathways for improving on-site dynamic quality evaluation; meanwhile, real-time monitoring and feedback control systems provide the foundation for intelligent vibration construction. However, the practical implementation of these technologies requires further validation under real construction conditions, particularly in complex scenarios. Finally, this review points out the significant research directions on which future breakthroughs in intelligent vibration technology and concrete vibration theory will depend. This review has important reference value for grasping the academic research trends and engineering application status in this field. Full article

(This article belongs to the Special Issue Development and Research of Cement-Based Materials)

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22 pages, 1291 KB

Open AccessArticle

Full-Scale Test and Finite Element Analysis of Flat Tempered Glass Sheets Subjected to Long-Edge Bending

by Wentao Li, Jie Ming, Wenjian Chen, Jianghao Zhou, Xiaoxiong Zha, Hualin Cao and Wei Wei

Buildings 2026, 16(18), 3740; https://doi.org/10.3390/buildings16183740 (registering DOI) - 20 Sep 2026

Abstract

Flat tempered glass sheets subjected to cold bending have been increasingly used in modern architectural curtain walls due to its extremely low production and processing costs and construction flexibility. However, existing studies mainly focus on small-size specimens, and there is still a lack [...] Read more.

Flat tempered glass sheets subjected to cold bending have been increasingly used in modern architectural curtain walls due to its extremely low production and processing costs and construction flexibility. However, existing studies mainly focus on small-size specimens, and there is still a lack of systematic understanding of the mechanical behavior of large-size monolithic tempered glass under long-edge cold bending. This knowledge gap leads to either unsafe or overly conservative curtain wall designs, limiting the popularization and application of flat tempered glass subjected to cold bending in large-curved curtain walls. This paper presents a comprehensive investigation into the bending behavior of flat tempered glass sheets—3200 mm × 1700 mm × 8 mm monolithic tempered glass—under long-edge cold bending conditions, through full-scale tests, finite element simulations and theoretical derivations. Firstly, cold bending tests on three full-scale tempered glass specimens were completed to obtain the failure process, failure modes, ultimate loads, failure displacements and stress distribution laws. The initial tempered residual stress of each specimen was measured to consider its influence on the mechanical response. Secondly, a refined finite element model was established in ABAQUS, which incorporated the initial tempered stress field, self-weight deformation and contact nonlinear effects. The accuracy of the model was verified through failure location, ultimate load, displacement and load-displacement curves, with average errors of less than 5.1% for both load and displacement predictions. Finally, parametric analysis was carried out based on the validated model to reveal the influence laws of glass width and thickness on the cold bending performance. The results show that glass thickness has the most significant influence on the bearing capacity, followed by length, while width has a relatively minor effect. This study provides basic data and model support for the safe application of flat tempered glass sheets subjected to long-edge bending. Full article

(This article belongs to the Special Issue Innovations in Structural Materials and Performance-Based Building Design)

22 pages, 20544 KB

Open AccessArticle

Progressive Collapse Resistance of Steel Frame Structures with Different Connection Stiffness Considering the Corrosion Effect

by Xiaotong Ma, Jinyu Wang and Yuxiao Xing

Buildings 2026, 16(18), 3739; https://doi.org/10.3390/buildings16183739 (registering DOI) - 20 Sep 2026

Abstract

Steel corrosion reduces structural cross-sections, mechanical properties, and durability, threatening structural safety. Beam–column joint stiffness also significantly influences the overall performance of steel frames. This study investigated the progressive collapse resistance of corroded steel frame joints considering different connection stiffnesses and corrosion levels. [...] Read more.

Steel corrosion reduces structural cross-sections, mechanical properties, and durability, threatening structural safety. Beam–column joint stiffness also significantly influences the overall performance of steel frames. This study investigated the progressive collapse resistance of corroded steel frame joints considering different connection stiffnesses and corrosion levels. A planar substructure consisting of one column and two half-span beams was adopted, and the central-column-loss scenario was investigated using displacement-controlled nonlinear static analysis to obtain the resistance–displacement response. The results showed that welded connections exhibited the highest strength and initial stiffness but experienced pronounced resistance degradation after fracture initiation. Fully bolted connections exhibited greater deformation accommodation capability but the lowest strength and initial stiffness. Welded–bolted connections provided intermediate strength and stiffness and achieved a relatively balanced response in terms of load-carrying capacity, energy absorption, and deformation accommodation capability. Under the investigated corrosion conditions, all three connection configurations exhibited progressive capacity degradation with increasing corrosion. The welded–bolted connection maintained relatively stable mechanical performance, whereas the fully bolted connection showed the greatest sensitivity to corrosion-induced deterioration among the three configurations. Among the three connection configurations examined, approximately 10% corrosion emerged as an indicative transition level for progressive collapse resistance within the investigated range. These findings provide a practical basis for connection selection and corrosion-management strategies in the progressive-collapse-resistant design and maintenance of steel frames. Full article

(This article belongs to the Special Issue Seismic Analysis and Design of Building Structures—2nd Edition)

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30 pages, 16559 KB

Open AccessArticle

Orientation-Resolved Thermal and Hygric Performance of Camel-Hair-Reinforced Rammed-Earth Walls Versus Hollow Concrete Block: A Six-Month, Two-Climate Comparative Field Study

by Laila Alqahtani and Kareem Aldali

Buildings 2026, 16(18), 3738; https://doi.org/10.3390/buildings16183738 (registering DOI) - 20 Sep 2026

Abstract

Field evidence for earthen and natural-fibre walls in hot climates remains scarce. This study reports a six-month field comparison of two wall constructions, instrumented on both faces at Riyadh (hot-arid) and Taif (milder highland), Saudi Arabia. Twenty-four sensors logged temperature and humidity every [...] Read more.

Field evidence for earthen and natural-fibre walls in hot climates remains scarce. This study reports a six-month field comparison of two wall constructions, instrumented on both faces at Riyadh (hot-arid) and Taif (milder highland), Saudi Arabia. Twenty-four sensors logged temperature and humidity every 15 min on three orientations of two open test cells with identical 300 mm walls: one of rammed earth reinforced with camel hair, the other of hollow concrete block. Twelve outer/inner wall pairs were analysed over 1708 wall-days. The earth wall damped the daily temperature swing more than the concrete block in every orientation at both sites: mean decrement factor 0.42 versus 0.58 at Taif and 0.47 versus 0.64 at Riyadh, holding on 86–99% of matched days. Mean inner-face amplitude fell from 12.5 to 7.0 °C at Riyadh. Time lag reached 3.2 h at Riyadh against 1.3 h for concrete block, but the materials were indistinguishable at Taif. Once construction moisture had dissipated, the earth wall damped the daily absolute-humidity swing by 57–58% against 11–48% for concrete block. Because the cells are open and unconditioned, these descriptors are comparative indices rather than transferable wall properties, and no cooling-load saving is inferred. Full article

(This article belongs to the Section Building Materials, and Repair & Renovation)

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13 pages, 2671 KB

Open AccessArticle

Influence of Support Equivalent Stiffness on Stability Capacity of Concrete-Pier-Supported Elliptical Cylindrical Double-Layer Reticulated Shell

by Pengfei Ma and Shuming Jia

Buildings 2026, 16(18), 3737; https://doi.org/10.3390/buildings16183737 (registering DOI) - 20 Sep 2026

Abstract

Concrete pier-supported double-layer reticulated shells are widely used in long-span industrial buildings, yet the influence of support equivalent stiffness on structural stability remains insufficiently understood. This study investigates the stability behavior of an elliptical cylindrical double-layer reticulated shell supported by concrete piers with [...] Read more.

Concrete pier-supported double-layer reticulated shells are widely used in long-span industrial buildings, yet the influence of support equivalent stiffness on structural stability remains insufficiently understood. This study investigates the stability behavior of an elliptical cylindrical double-layer reticulated shell supported by concrete piers with steel bearings. A simplified calculation method for equivalent support stiffness is derived based on a series cantilever system model and validated numerically. Seven steel bearing web thicknesses (10–40 mm) commonly used in engineering practice are selected, yielding equivalent stiffness coefficients ranging from 0.017 to 0.065. Eigenvalue buckling analysis is performed, and three quantitative indicators—critical load factor, sensitivity, and saturation degree—are introduced to systematically evaluate the effect of equivalent stiffness on stability capacity. Results show that the equivalent stiffness coefficient is typically less than 0.1, and using rigid links (infinite stiffness) overestimates the stability capacity by approximately 7% compared with the lowest stiffness case. The sensitivity of stability capacity to stiffness decreases monotonically as equivalent stiffness increases, with a threshold identified at ξ = 0.05. When the saturation degree of the critical load factor exceeds 72%, further increasing equivalent stiffness yields diminishing returns. Buckling modes transition from local end uplift to overall lateral tilting as equivalent stiffness increases. These findings provide a theoretical basis for selecting rational support stiffness values in the design of concrete-pier-supported reticulated shell structures. Full article

(This article belongs to the Section Building Structures)

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24 pages, 2953 KB

Open AccessArticle

Evacuation Time Variability Caused by Equal-Cost Path Selection in Underground Station Routing

by Hyunseok Kim, Sunnie Haam, Mintaek Yoo and Woo Seung Song

Buildings 2026, 16(18), 3736; https://doi.org/10.3390/buildings16183736 (registering DOI) - 20 Sep 2026

Abstract

In evacuation analysis for underground stations, Dijkstra’s algorithm is widely used to estimate the maximum evacuation time on the assumption that it returns a unique and reproducible route. This assumption does not hold in structurally symmetric networks, where many routes share an identical [...] Read more.

In evacuation analysis for underground stations, Dijkstra’s algorithm is widely used to estimate the maximum evacuation time on the assumption that it returns a unique and reproducible route. This assumption does not hold in structurally symmetric networks, where many routes share an identical cost and the route actually returned depends on an arbitrary, implementation-dependent tie-breaking rule. The aim of this study is to quantify how much the maximum evacuation time varies solely as a result of this tie-breaking rule, and to determine how many repeated executions are required before that variability is adequately characterized. A six-level underground station network of 720 nodes and 2222 edges was used. A random tie-breaking rule was implemented within Dijkstra’s algorithm, and the evacuation simulation was repeated under independently seeded runs of 1, 10, 25, 50, 100, and 1000 iterations while the station layout, movement speeds, congestion thresholds, and evacuee distribution were held fixed. A single execution produced a maximum evacuation time of 782 s, whereas the 1000-iteration case yielded a range of 671–864 s. The mean and median stabilized within 10–25 iterations, but the observed minimum and maximum continued to widen through 1000 iterations. These results show that a single Dijkstra execution can reasonably estimate typical evacuation performance but may underestimate the upper-tail evacuation times that govern life-safety design. For practical application to underground station design and evacuation-time verification, it is recommended that Dijkstra-based route generation be repeated across multiple tie-breaking realizations and that upper-percentile evacuation times be reported alongside the deterministic single-run result, so that the required safe egress time used in life-safety assessment reflects the variability inherent in equal-cost path selection. Full article

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41 pages, 1192 KB

Open AccessArticle

Stress-Testing Prescriptive Building Thermal Code Under Climate Non-Stationarity: Quantifying the Compliance–Performance Gap in Algiers Residential Buildings

by Meskiana Boulahia, Marwa Afaifia, Asmaa Tellache, Siham Chourouk Serrai, Kahina Amal Djiar and Shady Attia

Buildings 2026, 16(18), 3735; https://doi.org/10.3390/buildings16183735 (registering DOI) - 19 Sep 2026

Abstract

Prescriptive building thermal regulations, premised on stationary climate assumptions, risk masking operational performance deficits as warming accelerates. This study defines and quantifies the compliance–performance gap as the divergence between the climate-driven response of a regulatory criterion and the climate-driven response of the building’s [...] Read more.

Prescriptive building thermal regulations, premised on stationary climate assumptions, risk masking operational performance deficits as warming accelerates. This study defines and quantifies the compliance–performance gap as the divergence between the climate-driven response of a regulatory criterion and the climate-driven response of the building’s thermal performance over the same transition from a reference climate to a projected future climate. A standardised residential archetype representing the mass-housing stock in Algiers, calibrated against billing data from 177 dwellings and compliant with DTR C3.2/4, was simulated in EnergyPlus under morphed CMIP6 weather files (SSP2-4.5, SSP5-8.5 for 2050 and 2080). The official single-hour compliance test was reapplied alongside time-integrated metrics the code omits: over-heating degree-hours (OHDH28), night-time exceedance hours (NEH26), thermal autonomy (TA) and energy use intensity (EUI). The archetype remained formally compliant under all scenarios, while the summer compliance margin decreased from 7.14% to 0.05%. Under SSP5-8.5 in 2080, OHDH₂₈ increased by 297%, NEH26 reached 98.1% of summer night-time hours, TA decreased from 51.8% to 43.4%, and cooling EUI increased by 351%. Over the same transition, the regulatory response changed by only 7.6%, yielding divergence ratios of 38.9 for OHDH₂₈ and 45.9 for cooling EUI. Present-day compliance with thermal regulations does not ensure building resilience under future climate conditions. A staged transition toward time-integrated performance metrics and climate-linked revision cycles is necessary to improve the climate resilience of prescriptive codes, particularly in Mediterranean climates (Köppen Csa). Full article

(This article belongs to the Special Issue Integrating AI for Intelligent, Adaptive, and Energy-Efficient Building Design)

23 pages, 5029 KB

Open AccessArticle

Study on the Hysteretic Behavior of Post-Tensioned Unbonded Prestressed Concrete Beam–Column Joints with Two-Stage Energy Dissipation

by Qiuyue Zhou, Xiaoyun Sun, Linjie Huang and Yuxi Zhu

Buildings 2026, 16(18), 3734; https://doi.org/10.3390/buildings16183734 (registering DOI) - 19 Sep 2026

Abstract

To address the shortcomings of rapid stiffness degradation and single energy dissipation mechanisms in conventional post-tensioned unbonded prestressed concrete beam–column joints, this paper proposes a beam–column joint configuration that integrates a “friction-bending” two-stage energy dissipation mechanism. By adopting a low-prestress strategy, the joint [...] Read more.

To address the shortcomings of rapid stiffness degradation and single energy dissipation mechanisms in conventional post-tensioned unbonded prestressed concrete beam–column joints, this paper proposes a beam–column joint configuration that integrates a “friction-bending” two-stage energy dissipation mechanism. By adopting a low-prestress strategy, the joint enhances the energy dissipation ratio. Furthermore, energy dissipation bars with a secondary activation function in the energy dissipater form a stable third stiffness, thereby improving the hysteretic performance under large structural deformations. To clarify the influence of key design parameters on the hysteretic performance of the joint, this study established a refined finite element model using OpenSees3.3.0. A systematic parametric analysis was subsequently conducted, covering the number of prestressing tendons, initial prestress force, friction force, diameter of energy dissipation bars, and activation displacement ratio. The results indicate that the number of prestressing tendons only regulates the second stiffness and bearing capacity of the joint, with no significant effect on the energy dissipation capacity. The initial prestress force has limited influence on the joint stiffness and absolute energy dissipation; reducing the prestress can increase the equivalent viscous damping ratio by approximately 32%. The friction force is linearly and positively correlated with the activation force, enabling independent control of the joint’s energy dissipation capacity. Increasing the friction force can enhance the energy dissipation per cycle by 21.7%, without affecting the stiffness at each stage. The third stiffness is dominated by the compression-bearing mechanism of the energy dissipation bars. Enhancing the third stiffness can increase the peak loading capacity of the joint by 28.7%, while slightly improving the ultimate energy dissipation capacity. The research finding can provide a theoretical basis for the collaborative optimization design that achieves “low prestress for efficiency enhancement, friction dissipation for guaranteed energy absorption, and third stiffness for safety assurance.” Full article

(This article belongs to the Special Issue Advancements in Smart Civil Engineering: Durability, Seismic Resilience, Construction, and Composite Repair Technologies—2nd Edition)

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29 pages, 2731 KB

Open AccessArticle

Older Adults’ Perceived Visual Safety in Urban Pocket Parks: Environmental Problems and Design Implications from Four Cases in Nanjing, China

by Yan Li, Yuxin Cheng, Zhen Wu and Hao Zou

Buildings 2026, 16(18), 3733; https://doi.org/10.3390/buildings16183733 (registering DOI) - 19 Sep 2026

Abstract

Urban pocket parks support older adults’ daily activities, yet unclear visual–spatial information can complicate movement. This multiple-case study examined perceived visual safety among older users of four pocket parks in Nanjing, China, using 386 questionnaires, interview notes from 45 participants, and field records. [...] Read more.

Urban pocket parks support older adults’ daily activities, yet unclear visual–spatial information can complicate movement. This multiple-case study examined perceived visual safety among older users of four pocket parks in Nanjing, China, using 386 questionnaires, interview notes from 45 participants, and field records. Predictor-specific de-overlap models, in which overlapping outcome items were removed, served as the primary association analyses. None of the six environmental-problem ratings was significant after Holm correction. In a secondary model using the exploratory 20-item composite, boundary ambiguity and interface conflict were associated with lower values of the exploratory 20-item composite, although the outcome retained conceptually overlapping items. The preliminary questionnaire had a Cronbach’s α of 0.890, but parallel analysis supported four rather than five prespecified domains; visual comfort did not form a distinct factor, and the resulting 20-item composite was treated as exploratory. Mean values of the exploratory 20-item composite were higher in P1 and P2 than in P3 and P4. Interview and field evidence linked reported difficulties to routes, boundaries, level transitions, obstructed sightlines, and movement–activity interfaces. The findings locate perceived visual-safety problems at specific spatial decision points and suggest potential renewal priorities, including clearer route cues, more legible boundaries and level changes, unobstructed sightlines, and clearer organization of walking and activity areas. Full article

(This article belongs to the Section Architectural Design, Urban Science, and Real Estate)

48 pages, 15131 KB

Open AccessArticle

An Integrated Model for the Updatable Monitoring of Residential Building Construction Costs

by Spartaco Paris, Francesco Tajani, Giuseppe Cerullo and Giulia Famiglietti

Buildings 2026, 16(18), 3732; https://doi.org/10.3390/buildings16183732 (registering DOI) - 19 Sep 2026

Abstract

This study presents a methodological framework for the parametric assessment of residential construction costs, designed to support decision-making processes through systematic cost monitoring and continuous updating. The approach is grounded in a Work Breakdown Structure (WBS) decomposition, organising the building process into hierarchical [...] Read more.

This study presents a methodological framework for the parametric assessment of residential construction costs, designed to support decision-making processes through systematic cost monitoring and continuous updating. The approach is grounded in a Work Breakdown Structure (WBS) decomposition, organising the building process into hierarchical intervention categories and working clusters that enable clear cost attribution and aggregation at each level. The framework is applied to fourteen residential case studies located predominantly in the Municipality of Rome, Italy, organised in two phases: Phase I (five cases, with one excluded as anomalous) and Phase II (nine additional cases). A logical–deductive procedure introduces homogenization coefficients for accessory surfaces relative to the primary usable area, enabling the derivation of consistent, comparable unit construction costs and analysis of the relative economic weight of each cost component. Results are validated against official parametric benchmarks and delivered through operational tools—including interactive project sheets and GIS-based maps—that support both analytical interpretation and territorial comparisons. The framework is designed to be readily updatable through the integration of new cost inputs. Overall, the proposed model constitutes an applied instrument for monitoring and analysing construction costs in relation to building typology and territorial context, providing concrete support for the planning and economic management of residential construction. Full article

(This article belongs to the Section Construction Management, and Computers & Digitization)

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29 pages, 13560 KB

Open AccessArticle

The Impact of Controlled-Chamber U-Value Measurements on Building Energy Modelling: Evidence from Sustainable Wall Materials

by Iván García Kerdan, Virginia Gori, Lydia Pérez Pastrana, Eduardo Francisco Reyes de Luna, Samuel Antonio Rosas-Meléndez, Laura Camila Marín Gómez, Johanes Eduardo Chavez Díaz, Mario Alexander Ruiz Chiran, Amairani Yuritzi Elias Bravo, Nayeli Pérez Contreras and David Morillón Gálvez

Buildings 2026, 16(18), 3731; https://doi.org/10.3390/buildings16183731 (registering DOI) - 19 Sep 2026

Abstract

Building energy models rely on the wall thermal transmittance (U-value), yet, for locally available and novel sustainable materials, this input is usually taken from tabulated conductivities rather than measured, introducing an unquantified bias. The conductivity (k) and transmittance ( [...] Read more.

Building energy models rely on the wall thermal transmittance (U-value), yet, for locally available and novel sustainable materials, this input is usually taken from tabulated conductivities rather than measured, introducing an unquantified bias. The conductivity (k) and transmittance (U) of five locally available sustainable wall materials for social housing in the Mexico City Metropolitan Area—an adobe-type block, volcanic stone, tepetate ashlar, and solid and hollow sargassum-based concrete (SBC)—were estimated from heat-flux and temperature measurements on

1 m^{2}

specimens tested in a controlled two-room chamber (17 and 30 °C) using the ISO 9869-1 heat-flow-meter method, and benchmarked against a conventional concrete reference held at its tabulated value. Three reductions were compared—the ISO 9869-1 average method, a direct air-to-air estimate, and a dynamic grey-box (2R1C) model—which agreed within about 5%, with 1–6% repeatability. For four materials, the estimated U was 15–32% below the tabulated value, whereas the hollow SBC block exceeded it (

+ 11 %

), showing that tabulated inputs can err in either direction. Propagated through a whole-building EnergyPlus model of a representative social-housing archetype, the measurement-derived transmittances changed the predicted annual heating-plus-cooling demand by

- 28

to

- 42 %

for the four better-insulating walls and

+ 19 %

for the hollow block—a shift large enough to reorder the materials—scaling almost linearly with U (

R^{2} = 0.95

). The values are reported as controlled-chamber, element-level estimates, and an open, simulation-ready material database accompanies the paper. Full article

(This article belongs to the Section Building Energy, Physics, Environment, and Systems)

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