Search Results (1,549)

With the rapid development of prefabricated bridge construction, traditional manual bending and welding techniques for stirrups increasingly reveal limitations in efficiency, quality, and safety. To promote intelligent technologies in smart girder yards, this study establishes and reports an automated logistics system covering the entire workflow of bending–delivering–welding–storage for reinforcement processing, alongside key innovations, including an integrated stirrup bending workstation, an intelligent rebar cage welding station, and laser-adaptive seam-tracking technology. The results demonstrate that the system achieves fully automated and standardized construction of rebar cages, achieving 100% compliance in quality parameters (e.g., rebar spacing) while eliminating quality risks. Implementation in the G107 Chinese National Highway retrofit project reduced the site footprint by 27%, labor input by 40%, and construction duration by 60% compared with conventional prefabrication yards, saving CNY 3.38 million per thousand girders and reducing rebar consumption by 50 metric tons. This research provides a replicable technical pathway for intelligent bridge construction and significantly advances the mechanization and digitalization of rebar processing and welding. Full article

To reveal the mesoscopic fracture mechanism of fissured concrete, this study employed the discrete element method (DEM) and adopted the parallel bond model (PBM) within the two-dimensional particle flow code (PFC2D) to construct a mesoscopic model of concrete semi-circular bending (SCB) specimens with prefabricated fissures. Three sets of schemes were designed by varying prefabricated fissure angles (0–45°), aggregate contents (30–45%), and porosities (3–6%), and numerical simulations of three-point bending loads were conducted to explore the effects of each parameter on the crack propagation law and load-bearing performance of the specimens. Validation was performed by comparing the simulated load–displacement curves with the typical quasi-brittle mechanical characteristics of concrete (exhibiting “linear elastic rise–pre-peak stress fluctuation–nonlinear decline”) and verifying that the DEM could accurately capture the entire process from microcrack initiation at the aggregate–mortar interface, crack deflection/bifurcation induced by pores, to macroscopic fracture penetration—consistent with the known mesoscopic damage evolution law of concrete. The results indicate that the crack propagation mode evolves from straight extension to tortuous branching as parameters change. Moreover, the peak strength first increases and then decreases with the increase in each parameter: when the fissure angle is 15°, the aggregate content is 35%, and the porosity is 4%, the specimens achieve an optimal balance between crack propagation resistance and energy dissipation, resulting in the best load-bearing performance. Specifically, the prefabricated fissure angle dominates the stress type (tension–shear transition); aggregates regulate crack resistance through a “blocking–diverting” effect; and pores, acting as defects, influence stress concentration. This study verifies the reliability of DEM in simulating concrete fracture behavior, enriches the mesoscopic fracture theory of concrete, and provides reliable references for the optimization of concrete material proportioning (e.g., aggregate–porosity ratio adjustment) and anti-cracking design of infrastructure (e.g., pavement, tunnel linings) in engineering practices. Full article

Fire hazard presents a critical challenge to the structural reliability of underground modular infrastructure. This study examines the fire resistance performance of prefabricated monolithic utility tunnels featuring longitudinal threaded connections. A series of fire exposure tests was conducted on assembled utility tunnel specimens using different bolt materials and thermal conditions, enabling evaluation of fire behavior, deformation behavior, and residual capacity. The observed thermal properties revealed significant temperature gradients across tunnel sections, with the peak internal–external differential reaching 536.8 °C. Post-fire mechanical degradation was evident in reduced stiffness and ductility, and the residual load-bearing capacity declined by up to 12.28% compared to unexposed specimens. Specimens using high-strength threaded bolts demonstrated superior performance compared to stainless steel bolt specimens, exhibiting a 4.67% higher residual capacity and 13.87% less residual deformation. A sequential thermal–mechanical finite element model was developed and calibrated based on experimental results, offering a reliable simulation framework for investigating fire-induced damage and residual strength in modular utility tunnel systems. These findings provide a quantitative basis for fire safety assessment. Full article

In the newly developed hybrid prefabricated RC-steel structure (SS) foundation pit bracing system, the main braces are the main load-carrying components, which are assembled from standardized prefabricated reinforced concrete beam segments (referred to as beam segments). To facilitate assembly, beam segments are equipped with beam sleeves and beam-end connection holes. The holes at the end of the beam can cause stress concentration problems, while the beam sleeve has a reinforcing effect on the end of the beam segment. To investigate the influence of beam-end holes and beam sleeves on the compressive mechanical properties of beam segments, a numerical simulation study was conducted. Taking the beam segment (specification: 4500 mm × 700 mm × 800 mm) used in a certain foundation pit support project as the research object (i.e., specimen), Abacus software was first used to build parameterized models of beam segments with holes and beam sleeves using the concrete damaged plasticity model (CDP) and the steel double-line strengthening model. Then the influence of three factors, namely end face friction coefficient, beam-end holes diameter, and beam sleeve thickness, on the axial compression performance of the beam segment specimens was studied. The results indicated that the axial compressive capacity of specimens without a beam sleeve decreased with increasing hole diameter; the axial compressive bearing capacities of specimens with hole diameters of 35 mm, 40 mm, and 45 mm were 13,300 kN, 12,500 kN, and 12,300 kN, respectively, which are 11.3%, 16.7%, and 18% lower than the compressive bearing capacity of specimens without holes (15,000 kN). When both a beam sleeve and holes were present, the holes had a negligible influence on the compressive capacity, while the beam sleeve played a decisive role. The compressive bearing capacity increased with greater beam sleeve thickness; the peak bearing capacities of the specimens with beam sleeves 5 mm, 10 mm, and 15 mm thick were 16,200 kN, 16,500 kN, and 17,600 kN, respectively. As the end face friction coefficient decreased from 0.6 to 0.1, the location of maximum compressive damage shifted toward the end face of the beam segment, and the area of maximum concrete damage gradually migrated toward the hole locations. The study demonstrates that the confinement effect of the beam sleeve can compensate for the weakening effect caused by the holes and confirms that the designs of holes in beam segment ends and in the beam sleeve can meet safety requirements. Full article

In order to surmount the characteristics of high steel consumption and cost in prefabricated buildings, as a novel structural component, reinforced concrete vierendeel sandwich plates (RC-VSP) could be effectively employed. However, RC-VSP is restricted by complex construction procedures and rigorous quality control demands. Reliable reinforcement connections are the keys to their prefabrication. This study employed the methods of 1:1 full-scale comparative tests and numerical analysis through finite- element modeling. It compared the mechanical behaviors of the continuous reinforcement control group and the upset sleeve assembly group under four-point cyclic bending conditions. It analyzed how sleeves’ distribution influences structural stress states and crack propagation processes. The results show a superior ductility and damage resistance, on the basis of the components’ attenuation amplitude of the secant stiffness remains around 50% after the loading test with a deflection of 1/100, and the equivalent damping ratio is greater than 13%. Furthermore, the high similarity of the strain responses demonstrated the connection achieves prefabricated structures’ “equivalent performance to cast-in-place ones”. Additionally, the sleeve joints have slightly better stiffness, minor stress concentration at sleeve ends. This study offers robust experimental and theoretical support for the integrated prefabricated application of RC-VSP and further facilitates the development of building structures toward higher efficiency and lower carbon emissions. Full article

The incorporation of agricultural waste into construction materials represents a promising pathway toward achieving carbon neutrality in the building sector. This study investigates the flexural performance of a novel prefabricated external wall panel composed of corn straw concrete (CSC), an eco-friendly composite material that utilizes waste corn straws. While prior studies have explored rice straw and hemp fiber concrete, they primarily focused on the mechanical properties of these materials rather than the design of prefabricated panels. This study fills the gap by optimizing reinforcement ratio and window opening layout for CSC panels, and validating their structural viability for prefabricated enclosures. An optimal mix proportion was identified, which meets the mechanical requirements for non-load-bearing applications. Four prototype panel specimens were subjected to out-of-plane monotonic loading, considering variables including reinforcement ratio (0.18% vs. 0.24%) and the presence of a window opening (25% area ratio). Results indicated that increasing the reinforcement ratio significantly enhanced the ultimate load capacity by up to 33.3% (from 45 kN to 60 kN)—an enhancement effect that was 12–15% higher than that of reported rice straw concrete. In contrast, the introduction of an opening reduced the ultimate load capacity by 11.1–16.7%. A detailed nonlinear finite element model (FEM) was developed and validated against experimental results. The validation results indicated deflection error of 7.7–12.8% (mean: 9.33%; SD: 2.05), ultimate load error of 7.7–11.1% (mean: 9.48%; SD: 1.32), and a correlation coefficient (R²) of 0.96 between simulated and experimental values. Furthermore, analytical methods for predicting the cracking moment (with an average error of 5.97%) and ultimate flexural capacity, based on yield line theory (with an average error of 8.43%), were proposed and verified. This study demonstrates the structural viability of CSC panels and provides a sustainable solution for waste reduction in prefabricated building enclosures, contributing to greener construction practices. Full article

Precast concrete sandwich panels (PCSPs) have been widely adopted for constructing exterior walls in prefabricated residential buildings, but they face threats from impact loads such as natural disasters, terrorist attacks, and runaway vehicles. Their impact performance directly affects the overall safety and durability of the structure. However, research on the impact performance of such exterior walls remains limited. In this study, LS-DYNA R11 software is employed to establish a numerical model of PCSPs. The proposed numerical simulation method is validated by comparing the results with existing experimental data. On the basis of this numerical method and adopting an actual prefabricated residential building project as the background, the damage behavior of three distinct types of PCSPs in a bedroom is numerically investigated under varying impact location and energy conditions. The results demonstrate that the interior wythe of the PCSPs studied in this work exhibit excellent stability under external impact loading, with the most of damage absorbed by the exterior wythe, which provides effective protection to the interior wythe. Compared with windowed PCSPs subjected to impact, loads at the same energy level exhibit concrete spalling and a more pronounced dynamic response. Additionally, the windowed surface of L-shaped PCSPs is more susceptible to generating significant dynamic responses, with the non-windowed side exhibiting at least 13.2% lower maximum displacement under impact compared to the windowed side. Full article

Achieving a decarbonized built environment in Canada requires proven, resilient, and scalable building envelope assemblies. In 2022, building operations accounted for 18% of Canada’s greenhouse gas (GHG) emissions, with space heating responsible for nearly two-thirds of this total. Alongside operational carbon reductions, embodied carbon emissions—stemming from the production and transport of building materials—must be prioritized during the design phase. Without intervention, construction materials could consume up to half of the remaining global 1.5 °C carbon budget by 2050. This paper highlights NRCan’s prototype, low-carbon, prefabricated panels filled with chopped straw and cellulose insulation under the Prefabricated Exterior Energy Retrofit (PEER) research project. The research advances confidence in performance and durability of biogenic materials by conducting controlled experiments, guarded hot box testing, and hygrothermal modelling. These panels present a promising pathway to drastically lower embodied carbon in the built environment. The validated hygrothermal model, accurate to between 3% and 7, enables assessment of hygrothermal performance across Canadian climates, retrofit scenarios and future climate conditions. This work supports the evidence for low-carbon or bio-based materials as a solution for Canada’s built environment. Full article

Rapid urbanization in developing regions presents a critical challenge to the provision of affordable housing. This systematic review, conducted following the PRISMA 2020 guidelines, analyzed 91 studies (2013–2024) from Scopus and Google Scholar to identify cost-effective materials and innovative techniques suitable for the developing context. Findings reveal that achieving affordability in developing regions requires a holistic approach that integrates material innovation with human capacity building. The analysis of critical success factors (CSFs) in the Rumah Unggul Sistem Panel Instant (RUSPIN) system from Indonesia and the Recycled Plastic Formwork (RPF) system from South Africa exemplifies this integration. Both systems show high potential for scalability and technological transfer using local materials and labor training. The review also highlights that materials commonly used in developed countries (e.g., autoclaved aerated concrete, expanded polystyrene, and light steel gauge framing) face adoption barriers in developing regions due to challenges related to supply chains, industry capacity, and regulatory frameworks. Conversely, locally available materials (e.g., earth, bamboo, and recycled waste) require ongoing research to enhance their availability and structural performance. Ultimately, achieving affordable housing depends on an integrated approach that combines locally sourced materials, innovative construction techniques, and the strategic application of critical success factors. Full article

This study presents a systematic evaluation of frost resistance in concrete modified with nano-alumina (NA, 1 wt%), nano-silica (NS, 2 wt%), and polypropylene fiber (PP, 0.2 wt%) through accelerated freeze–thaw testing. The investigation employed a comparative experimental approach, subjecting specimens with optimal mechanical dosages to 300 freeze–thaw cycles. The degradation was quantitatively assessed by monitoring the evolution of mass loss, dynamic elastic modulus, and compressive strength. Results reveal that PP-modified concrete demonstrates optimal performance, retaining 70% of its dynamic elastic modulus (vs. 68% for NA and 64% for control, and failing at 58% for NS after 200 cycles) and exhibiting only 9.3% compressive strength loss (vs. 13.9% for NA and 27.3% for control, and 43.6% for NS). These findings establish PP as the most effective modifier, offering both superior frost resistance (300+ cycle durability) and practical advantages (simpler processing, lower cost). The results provide a scientific basis for designing high-performance concrete in cold regions, with particular relevance to infrastructure requiring long-term durability under cyclic freezing conditions. Full article

Grouted sleeve connections are widely employed in the substructures of prefabricated bridges. After installation, the grout filling condition inside the sleeves cannot be directly inspected, while grouting defects may significantly compromise the mechanical performance of the piers. This study investigates the feasibility of using the non-destructive impact-echo method to detect grouting defects in sleeves. Finite element simulation was conducted to analyze the influence of the distance between the impact point and the signal acquisition point on detection accuracy, revealing that a distance of 40–60 mm yields optimal results. Experimental findings demonstrate that the method can effectively identify grouting defects in double-row sleeves, although it cannot precisely locate the defective sleeve. A novel analytical approach is proposed, using the thickness frequency and its modes of fully grouted specimens as a benchmark. By comparing thickness frequencies at different measurement points, grout quality can be intuitively evaluated. Validation using a six-sleeve model with varying grouting densities confirmed the method’s effectiveness in detecting grouting defects in non-boundary sleeves and its practical applicability in engineering. Full article

The construction industry is transforming toward innovative and sustainable building methods, with modular building emerging as a viable alternative to conventional techniques. Modular building practices (MBPs) are regarded as an efficient and sustainable alternative driven by the need to reduce costs, minimise material waste, improve project timelines, and meet technological and environmental demands in the construction industry. This study, therefore, explores the key factors promoting the adoption of MBPs within the construction space. Using a quantitative research design, data were collected through structured questionnaires administered to registered and practising construction professionals, including architects, engineers, project managers, and quantity surveyors across various construction firms in South Africa. The instrument’s reliability was confirmed with a high Cronbach’s alpha coefficient of 0.974, indicating excellent internal consistency. Findings reveal that education and training, increased funding for research and development, tax imposition on traditional building components, introducing relevant support policies and legislations, and awareness creation among the stakeholders are key drivers of MBPs. The findings underscore the importance of aligning industry practices with policy incentives, investing in workforce upskilling, and enhancing stakeholder engagement to accelerate the transition toward modular construction. The study contributes to both the academic literature and industry knowledge by providing empirical evidence on the multidimensional factors promoting modular practices. Implementation of supportive regulations and incentives that promote sustainability, streamlined approval processes, and innovation is highly recommended. Full article

The construction of prefabricated timber buildings is a topic of growing interest, although research has primarily focused on technological aspects, while the users’ perspective remains underexplored. Accordingly, this paper aims to map the existing literature on prefabricated wooden buildings from a user-centered perspective, considering the whole-building scale. A systematic literature search of publications between 2010 and 2025 was conducted following PRISMA guidelines, identifying relevant studies. A bibliometric analysis was then performed to map key research themes, which were further examined through a scoping review. Four main themes emerged, i.e., indoor comfort, indoor air quality, sustainability and energy efficiency, and building architectural design. The findings highlight numerous aspects that should be considered in prefabricated timber buildings design, including thermal, vibrational and acoustic comfort, air pollutant and ventilation control, user behavior in relation to energy use, and spatial design based on users’ needs. However, the limited number of existing studies makes comprehensive evaluation difficult. Furthermore, the results emphasize the need for multidisciplinary approaches to adequately integrate user experience into the design of these buildings. Full article

Europe, including Poland, is undergoing an energy transition. The use of renewable energy sources (RES) in the national energy sector is increasing significantly, and previously unused areas are increasingly developed for photovoltaic power plants. A specific type of housing common in Eastern European countries opens an additional opportunity for photovoltaic installations without occupying usable ground area. This article aims to analyze the potential for utilizing balconies and loggias in large-panel buildings, which are characteristic of major cities in Poland. Approximately 30% of the population resides in such housing. This presents significant potential for direct use of renewable energy by apartment residents. The article also explores the legal framework for such installations, both as individual investments by apartment owners and as collective initiatives managed by building administrators. The authors analyzed the potential performance of photovoltaic installations under varying azimuths and tilt angles, considering solar irradiation potential. The analyses also encompassed different photovoltaic module technologies, covering a spectrum of photovoltaic technologies, from commonly used monocrystalline panels to advanced transparent BIPV (Building-Integrated Photovoltaics) solutions. Furthermore, the study quantified the energy potential of such installations and compared the results with existing photovoltaic capacities and electricity demand in Poland. Full article

Against the backdrop of policy-driven transformation in construction industrialization, the EPC general contracting model has emerged as a core pathway for the large-scale development of prefabricated buildings. However, the EPC mode integrates the links of design, procurement, production, and transportation, construction, resulting in a complex coupling correlation among the risk factors of prefabricated construction schedule, which is easy to induce the risk contagion effect and increase the difficulty of risk control of project schedule delay. To address this, this study constructs a hybrid model integrating the “Fuzzy Interpretive Structural Model (FISM)-Coupling Degree Model-Bayesian Network (BN)” to systematically analyze risk contagion mechanisms. Taking an EPC prefabricated building project as an example, FISM is used to reveal the hierarchical structure of risk factors, while the coupling degree model quantifies interaction strengths and maps them into the BN to optimize conditional probability parameters. Through comprehensive hazard analysis, seven key causal risk factors and two critical risk propagation paths are identified. Targeted control measures are designed for the key risk factors, and BN-based simulation is applied to locate critical risk nodes and implement break-chain interventions for the risk paths, resulting in a 23% reduction in the probability of schedule delay. Engineering applications demonstrate that this model can effectively achieve the dynamic identification and blocking of risk paths, providing valuable reference for similar projects and offering informed support for managers in formulating scientific response strategies. Full article