Search Results (12,408)

Concrete printing in three dimensions is believed to be an innovative construction method. Numerous researchers conducted laboratory experiments over the past decade to examine the behavior of concrete mixtures and the material properties that are pertinent to the 3D concrete printing industry. Furthermore, the global warming effect is being further exacerbated by the increased use of cement, which increases carbon dioxide (CO₂) emissions and pollution. Various standards endorse the utilization of Portland-composite cement in construction to mitigate CO₂ emissions, particularly cement CEM II/A-P. This research provides an experimental and numerical study to examine the evolution of cementitious composite utilizing cement CEM II/A-P for three-dimensional concrete printing, combining three different types of synthetic fiber. The thorough experimental analysis includes three combinations integrating diverse fiber types (polypropylene, high-modulus polyacrylonitrile, and alkali-resistant glass fibers) alongside a reference mixture devoid of fiber. The three distinct fiber types in the mixtures (polypropylene, high modulus polyacrylonitrile, and alkali-resistant glass fibers) were evaluated to assess their impact on (i) the flowability of the cementitious mortar and the slump flow test of fresh concrete, (ii) the concrete compressive strength, (iii) the uniaxial tensile strength, (iv) the splitting tensile strength, and (v) the flexural tensile strength. Previous researchers designed a cylinder stability test to determine the shape stability of the 3D concrete layers and their capacity to support the stresses from subsequent layers. Furthermore, the numerical analysis corroborated the experimental findings with the finite element software ANSYS 2023 R2. The flexural performance of the examined beams was validated using the Menetrey–Willam constitutive model, which has recently been incorporated into ANSYS. The experimental data indicated that the incorporation of synthetic fiber into the CEM II/A-P mixtures enhanced the concrete’s compressive strength, the splitting tensile strength, and the flexural tensile strength, particularly in combination including alkali-resistant glass fibers. The numerical results demonstrated the efficacy of the Menetrey–Willam constitutive model, featuring a linear softening yield function in accurately simulating the flexural behavior of the analyzed beams with various fiber types. Full article

In the loess-filling project, the original structural loess under the filling will produce creep deformation under the isometric consolidation stress state, affecting the upper building’s safe construction and later operation. Therefore, studying the creep deformation characteristics of structural loess under different consolidation coefficients is significant. In this paper, the following results are obtained by combining test and theoretical analysis. In view of the structural loess under the filling, the triaxial creep test of undisturbed loess under different isometric consolidation coefficients, confining pressures and shear stress levels was completed, and the creep deformation law of structural loess was obtained. The creep characteristics of undisturbed loess are found to be diversified under different coefficients, confining pressures, and shear stresses, including initial instantaneous deformation, subsequent creep attenuation deformation, and final stable creep deformation. The damage creep constitutive model of undisturbed loess is established, taking the binary medium model as the framework, the cementation element adopts the Nishihara model, the friction element introduces the overstress model and considers the isometric consolidation effect, and the damage creep constitutive model of undisturbed loess is established. The theoretical model is obtained by determining the relevant parameters of the constitutive model. The theoretical curve is compared with the experimental curve and shows that the damage creep model established in this paper can better reflect the creep of structural loess under isometric consolidation conditions well. The research results can provide systematic theoretical support and an experimental basis for the deformation problems involved in the filling project in the loess area. Full article

Second-hand housing transactions are an important part of the housing market. Due to the dual influence of location and price, the sales cycle of second-hand housing has shown significant diversity. As a result, when residents sell or buy second-hand houses, they often cannot accurately and quickly evaluate the cycle of the second-hand house; thus, the transaction fails. For this reason, this paper develops a prediction model of the second-hand housing sales cycle based on the hybrid kernel extreme learning machine (HKELM) optimized using the Improved Crested Porcupine Optimizer (CPO), which has achieved rapid and accurate prediction. Firstly, this paper uses a Stimulus–Organism–Response model to identify 33 factors that affect the second-hand housing sales cycle from three aspects: policy factors, economic factors, and market supply and demand. Then, in order to solve the problems of slow convergence, easy-to-fall-into local optimum, and insufficient optimization performance of the traditional CPO, this paper proposes an improved optimization algorithm for crowned porcupines (Cubic Chaos Mapping Crested Porcupine Optimizer, CMTCPO). Subsequently, this paper puts forward a prediction model of the second-hand housing sales cycle based on an improved CPO-HKELM. The model has the advantages of a simple structure, easy implementation, and fast calculation speed. Finally, this paper selects 400 second-hand houses in eight cities in China as case studies. The case study shows that the maximum relative error based on the model proposed in this paper is only 0.0001784. A ten-fold cross-test proves that the model does not have an over-fitting phenomenon and has high reliability. In addition, this paper discusses the performances of different chaotic maps to improve the CPO and proves that the algorithm including chaotic maps, mixed mutation, and tangent flight has the best performance. Compared with the classical meta-heuristic optimization algorithm, the improved CPO proposed in this paper has the smallest calculation error and the fastest convergence speed. Compared with a BPNN, LSSVM, RF, XGBoost, and LightGBM, the HKELM has advantages in prediction performance, being able to handle high-dimensional complex data sets more effectively and significantly reduce the consumption of computing resources. The relevant research results of this paper are helpful to predict the second-hand housing sales cycle more quickly and accurately. Full article

Due to the difficulties in sampling, high sensitivity to humidity, and inconvenience in storage, undisturbed loess is prone to changes in its original structure. Therefore, trace amounts of cement and salt are added to remolded soil to simulate the structure of undisturbed loess. The GDS dynamic three-axial test apparatus was used to investigate the influence of dry density, cement content, and confining pressure (CP) on the dynamic distortion characteristics of artificially structured soil. Based on dynamic triaxial tests, the Hardin–Drnevich (H-D) model was established through fitting analysis. The research findings indicate that increased dry density, cement content, and CP can enhance the soil’s resistance to distortion. Under dynamic loading, the higher the CP, the smaller the damping ratio of the soil. With a dry density of 1.20 g/cm³ and 2% cement, the dynamic modulus of the artificially structured loess is similar to that of undisturbed loess. With a dry density of 1.60 g/cm³ and 2% cement, the CP is 200 kPa, the soil’s dynamic modulus of elasticity (DM-E) peak value is 113.14 MPa, and the damping ratio is 0.258. The good agreement between trial data and the predicted results demonstrates that the H-D hyperbolic model is appropriate for representing the DM-E of artificially structured loess. A three-dimensional model of the dynamic deformation characteristics and microstructure of artificial structural loess under dynamic loads was established. The findings can guide the study of the mechanical properties of loess under dynamic loading. Full article

Despite the plethora of digital and technological advances made in the construction industry over the past three decades, at its core, the sector remains human-centric. Consequently, this research investigates the core soft skills employed on public linear infrastructure (PLI) projects (during the construction phase) that are digitally enabled and concludes with the development of a decision support tool for PLI project team management. A mixed philosophical stance is implemented using interpretivism, postpositivism and grounded theory together with abductive reasoning to examine subject matter experts’ perceptions of the phenomena under investigation. Textual analysis is then utilised to formulate a decision support tool as a theoretical construct. The research findings demonstrate that communication, leadership and creativity/curiosity are the three main soft skills required of PLI projects. Furthermore, the key elements of a decision support tool—namely, trackable and measurable data, clear objectives and success criteria, and an easy-to-understand visual format—were identified. Such knowledge provides a strong base for building an emotionally intelligent project team. This research constitutes the first attempt to understand the essential soft skills required on PLI projects and, premised upon this, generate a decision support tool for project management in teams that helps to augment project performance through workforce investment via a learning organisation. Full article

Throughout human settlement history, the pursuit of durability has been a paramount objective in building construction. The emphasis on durability has resulted in the construction of buildings designed to outlast human lifespans. However, the lack of consideration for building demolition and disposal during the design and construction phases has created challenges for future generations. This oversight contributes to the environmental impact of structures after demolition, which is a significant concern given that the construction industry is a major contributor to energy consumption, CO₂ emissions, and solid waste production. In fact, in recent decades, there has been an increasing demand for temporary constructions, driven by factors such as migration phenomena, natural disasters, and the COVID-19 pandemic, but also in sectors like agriculture, where seasonality and annual variations in activities require adaptable structures such as warehouses, barns, livestock shelters, and food storage facilities. Unlike traditional constructions, these temporary buildings must be assembled and disassembled multiple times during their lifespan. The challenge lies in ensuring the structural integrity, adaptability to varying conditions, and compliance with specific requirements to extend their usability and postpone the disposal phase. This study focuses on the design of a novel type of temporary structures intended for temporary needs such as emergencies and planned agricultural activities, resulting in a European patent. The structure is based on a glulam frame inside two OSB panels—that work as structural bracing, creating a hollow, resistant, light structure—connected with external steel connections. This work reports results of mechanical simulations and thermal transmittance calculations. Specifically, it demonstrates the building maintains structural strength through multiple usages and its thermal characteristics can be easily adapted to the context. These are the first steps for a resilient and sustainable building. Full article

Energy efficiency and CO₂ emission reduction are key objectives related to climate change mitigation, sustainable development, and energy resource management. In the Nordic context, energy consumption trends in both the residential and industrial sectors are closely linked to European Union policies, technological innovation, and real estate investments. In recent decades, the development and renovation of the real estate sector has become one of the most important factors determining changes in energy consumption, especially in residential buildings, which remain among the largest energy consumers and polluters. In this context, countries’ efforts to reduce CO₂ emissions and increase energy efficiency are inseparable from the real estate sector’s contribution to these processes, by promoting investments in building modernization and energy-saving technologies. However, the real estate sector remains a complex area where economic interests need to be reconciled with environmental objectives, especially in the context of EU strategies such as the Renovation Wave and the Energy Efficiency Directive. This article examines the links between real estate investment, energy efficiency, and CO₂ emission reduction, based on quantitative analysis, to assess how the development of the real estate sector and EU policy measures affect sustainable development in Northern Europe. This study uses advanced quantitative methods, including a panel regression model, which helps better reveal the long-term dependencies between investment, energy consumption, and emissions dynamics. This article highlights the importance of the real estate sector in implementing sustainability policies and suggests strategic solutions that can help reconcile economic and environmental priorities. Full article

Current research on analytical solutions for tunnel longitudinal deformation due to foundation pit excavation predominantly focuses on scenarios where the pit is perpendicular to the tunnel axis, with limited exploration of oblique intersection cases. This study employed the layer-wise summation method, grounded in the Mindlin solution, to determine the additional stress in the tunnel resulting from foundation pit excavation. The focus was on situations where the tunnel axis crosses the foundation pit axis at an oblique angle and where the tunnel is beneath the side wall of the foundation pit. A model was introduced to address the synchronized deformation of shield tunnel segment rings due to rotation and dislocation. A variational control equation, derived from the principle of minimum potential energy, evaluates longitudinal displacement, the ring-to-ring rotation angle, and tunnel dislocation. Two batches of engineering examples were assessed for the purposes of calculation and validation. The study reveals that the longitudinal deformation of tunnels intersecting at an oblique angle adheres to a Gaussian distribution and is asymmetrical relative to the center of the foundation pit excavation. In cases where the foundation pit and tunnel intersect obliquely, particularly when the tunnel is not directly below the pit, discrepancies between calculated and measured values can reach up to 5%. By contrast, not accounting for the oblique intersection can result in discrepancies of up to 300%. Therefore, the proposed method of calculation delivers a more accurate portrayal of the actual deformation behavior of tunnels in engineering practice. Full article

The primary objective of this study is to determine appropriate mixes for cement-based crack injection materials by combining Portland cement (type I) and sulfoaluminate cement (SAC) with reactive ultra-fine fly ash (RUFA). Various weight percentages of SAC (W_SAC) and Portland cement (type I) (W_C) as binder materials were considered, while the weight percentage of RUFA (W_RUFA) in the binder was fixed at 5%. The usage of RUFA enhances the fluidity and strength of the paste, while SAC helps to mitigate shrinkage and improve early strength. The results indicate that the mixture with a water-to-binder ratio of 0.4, W_SAC = 75%, W_C = 20%, and W_RUFA = 5% can meet the requirements of relevant standards in terms of injectability, average splitting tensile strength, bleeding rate, and volume change. In addition, this mixture provides optimal performance in terms of setting time, compressive strength, slanted shear strength, and length change. Full article

Construction material management is crucial for project progression. Counting massive amounts of scaffold components is a key step for efficient material management. However, traditional counting methods are time-consuming and laborious. Utilizing a vision-based method with edge devices for counting these materials undoubtedly offers a promising solution. This study proposed an edge-computing-driven approach for detecting and counting scaffold components. Two algorithm refinements of YOLOX, including generalized intersection over union (GIoU) and soft non-maximum suppression (Soft-NMS), were introduced to enhance detection accuracy in conditions of occlusion. An automated pruning method was proposed to compress the model, achieving a 60.2% reduction in computation and a 9.1% increase in inference speed. Two practical case studies demonstrated that the method, when deployed on edge devices, achieved 98.9% accuracy and reduced time consumption for counting tasks by 87.9% compared to the conventional method. This research provides an edge-computing-driven framework for counting massive materials, establishing a comprehensive workflow for intelligent applications in construction management. The paper concludes with limitations of the current study and suggestions for future work. Full article

The urgent need for climate change mitigation has increased the focus on reducing embodied carbon and energy, particularly in the construction sector. Utilizing sustainably sourced mass timber products provides a low-carbon alternative to traditional concrete and steel structural systems in buildings. These carbon impacts can be quantified by evaluating the total environmental impact of a building, from material extraction and product manufacturing to construction, operation, and demolition. This study evaluated the environmental impacts of a 14-storey mass timber–steel hybrid building in Madison, USA, through a Whole-Building Life Cycle Assessment (WBLCA) using the Tally LCA tool integrated with Autodesk Revit. The hybrid design was compared to full mass timber, full steel, and post-tensioned concrete structures, which are common structural systems for high-rise buildings, enabling meaningful comparisons of their environmental performance. The results showed that the full mass timber design had the lowest global warming potential (GWP), reducing emissions by 16% compared to the concrete structure. The hybrid design achieved a 14% reduction, with both timber-based systems demonstrating about 30% lower non-renewable energy use. In addition, they provided significant biogenic carbon storage during the building’s lifespan. However, the mass timber and hybrid systems showed higher impacts in categories such as acidification, eutrophication, ozone depletion, and smog formation. Full article

This study explores the design characteristics of approach spaces in architect Yoshiji Takehara’s independent residential works, focusing on their spatial arrangement, sinuosity, and experiential qualities. Through the analysis of Takehara’s projects and interviews with the architect, the research identifies key patterns in approach configurations, including entrance positioning, path complexity, and site-specific adaptations. The findings reveal that Takehara’s designs emphasize winding paths and deliberate spatial sequences, contrasting the simpler approaches of contemporaneous residential designs. The study categorizes approach configurations into distinct typologies, influenced by the site dimensions and entrance placement, and highlights a shift from physical obstructions to subtler, psychologically guided design elements over time. Takehara’s design method translates the concept of “Ma” from traditional tea gardens into the language of modern pathways, integrating traditional Japanese spatial ambiguity into contemporary residential design. This offers strategies to enhance spatial perception and experiential richness. Particularly in compact urban settings, the research provides valuable insights for contemporary residential design, emphasizing the importance of landscape-oriented approaches and spatial sequencing in creating meaningful entry experiences. Full article

Performance-based seismic design (PBD) has emerged as a key approach for rationalizing prescriptive code provisions and improving the explicit assessment of structural performance. In Chile, where reinforced concrete shear wall buildings are the predominant structural typology, evaluating their seismic response beyond traditional linear methodologies is crucial. This study assesses the seismic performance of a representative Chilean shear wall residential building using the ACHISINA manual’s performance-based seismic design framework. A nonlinear static (pushover) analysis is performed to verify compliance with prescribed design criteria, incorporating capacity design principles and a moment envelope approach to prevent premature yielding in upper stories. The results confirm that the building meets the performance objectives for both Immediate Occupancy and Additional Deformation Capacity limit states. The application of capacity design effectively controls shear demand, preventing brittle failure, while the flexural design ensures the formation of the yielding mechanism (plastic hinge) at the intended critical section. Additionally, the study highlights the limitations of pushover analysis in capturing higher-mode effects and recommends complementary nonlinear time-history analysis (NLTHA) for a more comprehensive assessment. The computed response reduction factors exceed those used in the prescriptive design, suggesting a conservatively safe approach in current Chilean practice. This research reinforces the need to integrate performance-based methodologies into Chilean seismic design regulations, particularly for shear wall structures. It provides valuable insights into the advantages and limitations of current design practices and proposes improvements for future applications. Full article

Cross-Laminated Timber (CLT) is ideal for tall timber structures but relies on environmentally concerning chemical adhesives. Nailed Cross-Laminated Timber (NCLT) offers a sustainable alternative by using densified wooden nails that form eco-friendly, adhesive-free bonds through lignin’s thermoplastic properties. However, significant uncertainties remain regarding the synergistic effects of multiple wooden nails. To address this, this study systematically analyzed the impact of the group effect on the mechanical performance of wooden nail joints. The results show that within the elastic range, the number of wooden nails has no significant effect on the elastic behavior of a structure. However, it is significantly positively correlated with both the joint yield load and yield displacement, enabling the accurate prediction of the structural yield point based on the number of wooden nails. With consistent nail arrangements, the group effect coefficient for the load-bearing capacity remains highly stable and shows no significant correlation with the number of nails. Additionally, an increase in the number of wooden nails significantly enhances the deformation resistance and structural stiffness, while having a minimal impact on ductility. This study reveals the linear additive nature of the group effect in wooden nails, providing important theoretical support for the design of NCLT. Full article