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•The most of parameters related to reinforced concrete have no effect on the capacity.•The most effective parameter for the capacity of the purlin is CFRP ply orientation.•±45° fiber ...orientation is recommended to prevent or delay shear damage.•Material properties of CFRP significantly affect the capacity of the purlin.•The number of CFRP plies should be selected carefully to avoid unnecessary use.
Dapped end prefabricated concrete purlins (PCPs) suffer from shear damages due to coating, snow, wind load and also their dead loads. In this present study, a series of numerical modelling is performed with the aid of finite element program ABAQUS in order to investigate this behavior of PCPs through parametric study. In addition to the mechanical properties of the PCPs, the strengthening of the PCPs with the help of carbon fiber reinforced polymers (CFRP) is considered as a parameter in the models. Pursuant to this aim, longitudinal steel reinforcement ratio, shear friction reinforcement ratio, bending reinforcement ratio, suspension reinforcement ratio, concrete and steel mechanical properties, pre-stressing level, CFRP ply orientation, the number of CFRP plies and material properties of CFRP composite were selected as the parameters. First of all, numerical models were verified using experimental test data of three PCP test specimens and five CFRP coupon tests. Later, a total of 50 different numerical models was created to investigate the behavior of PCPs thoroughly. Vertical load- displacements curves are compared and explained in detail. The result of the parametric study revealed that the effects of the parameters related to reinforced concrete except longitudinal reinforcement and material properties of concrete are very limited when compared to the effects of the parameters related to CFRP. The effect of FRP ply orientation is the most effective parameter that increases significantly the shear capacity of PCPs. More importantly is the general FRP layout is proposed to delay or prevent shear cracks for the beams and the proposed layout is proved through numerical analyses. ±45° fiber orientation is recommended to use to prevent shear damage.
Conventionally assembled monolithic concrete frame structures achieve structural ductility through beam-end failure, which results in structures that are difficult to repair after an earthquake. To ...improve the seismic and resilience performance, a prefabricated concrete beam–column joint with replaceable graded-yielding energy-dissipating connectors (RGECs) is introduced. The connectors assembled on the upper and lower sides of the beam end dissipate energy and transfer the beam-end load with the steel hinge device. By adjusting the design bearing-capacity coefficient of RGECs to precast beams, the plasticity and damage of the structure can be centered on the core energy-dissipation bending–shear components (BSCs) and buckling segment (BS) of the RGEC, and the structural function can be quickly recovered by replacing only the damaged RGECs after a seismic disaster. Moreover, compared to the conventional joints, the joint with RGEC can achieve target seismic-performance goals at different seismic-risk levels by designing BSCs and BS with graded yielding. Low-cyclic-loading tests were performed on seven full-scale beam–column joint specimens to investigate the effects of different core energy-dissipating member thicknesses, beam reinforcement ratios and loading protocols on the seismic behavior of the proposed joint. Subsequently, the damaged RGECs were replaced, and the structural-function resilience performance was evaluated in terms of the function-recovery efficiency and quality, indicated by the hysteresis response, strain development, and component energy dissipation. The experimental results proved that the beam–column joint exhibited excellent seismic performance and could realize graded-yielding energy dissipation. The damage to the specimens was concentrated in the RGECs, the key members (beams and columns) were in an elastic state, and the energy dissipation ratio of the RGEC was more than 97 %. This enables the rapid recovery of function after earthquakes. After replacing the RGEC, the hysteresis response, strain development, and component energy dissipation of the specimens were consistent with those of the initial specimens. Compared with the original specimen, the difference in each seismic index of the replaced specimen was less than 10 %. Additionally, the structural function recovered quickly, and the resilient performance was good.
•A prefabricated concrete beam–column joint with graded-yielding devices is proposed.•Seven specimens are cyclically tested to study seismic and resilient performance.•The joint can control the damage paths and meet different seismic-performance goals.•An evaluation method for structural-function resilience is proposed and applied.
•Bioinspired sandwich CFRP composite is 0.73–4.4 more cost effective compared to steel.•CFRP and recycled concrete is useful in lightweight prefabricated construction.•Barriers identified: ...behavioral, technical, infrastructural, market and legal barriers.•Advanced prefabricated construction recommended in future smart cities and new projects.•Welfare, safety training and collaboration required for Covid-19 resilient construction industry.
Modular prefabricated construction has attracted global attention to meet increasing housing demands and infrastructural deficits owing to its construction speed and efficiency. Unfortunately, the benefits of such modular prefabricated structures are undermined by heavy steel utilization, which is susceptible to corrosion, and contributes to their heavy weight leading to transportation and erection problems during construction. Bioinspired lightweight sandwich CFRP composite reinforcement is investigated as an alternative to steel along with recycled concrete for sustainable prefabricated construction using a performance-based hybrid Taguchi-Response surface methodology multi-objective optimization approach. The optimized result exhibited improved mechanical properties and favourable, ductile failure mode attributed to the Bauschinger strain-reversal effects and composite actions of the bio-inspired CFRP reinforcements. Comparatively, the bioinspired sandwich composite reinforcement was found to be 0.73–4.4 times more cost-effective than steel reinforced concrete structures in terms of fracture toughness and has potential applications in lightweight prefabricated (modular) concrete structures. This study also revealed prevalence of behavioral, technical, infrastructural, market and legal barriers which hinder adoption of prefabricated construction and can be overcomed through appropriate regulatory framework, standards, centers of excellence, demonstration projects and incentives for advanced prefabricated construction. Government authorities should promote advanced prefabricated composite construction in new construction projects and future smart cities to minimize construction wastes and carbon emission problems prevalent in most cities, provide employment support to construction companies, improving safety/welfare training and encourage collaboration among construction firms to improve resilience of construction industry to on-going Covid-19 and future pandemics and associated socio-economic impacts.
The prefabricated concrete buildings (PCBs）are the booster in the process of construction industrialization and intelligent upgrading. However, its high cost has become one of the restricting factors ...of further application and promotion of prefabricated concrete buildings. Moreover, the existing investment estimation methods of prefabricated concrete buildings have limited predicting accuracy as well as the ability of adapting dynamic factors. Therefore, to achieve more reliable and reasonable investment estimation of prefabricated concrete buildings, this paper has proposed an investment estimation model of prefabricated concrete buildings based on XGBoost machine learning algorithm. In the proposed model, the construction project cost-significance theory (CS) and analytic hierarchy process (AHP) were used to extract the construction characteristic indices of prefabricated concrete buildings investment estimation. Then the XGBoost machine learning algorithm was implemented to build an investment estimation model of prefabricated concrete buildings that was able to quantify the uncertainty of the confidence and prediction, and to enhance the interpretability of the model. The research conducted in this paper showed that when compared with traditional machine learning methods such as Support vector machine (SVM), Back Propagation Neural Network (BPNN) and Random Forest (RF), XGBoost had better generalization and interpretable ability. The discussion provided in this paper further demonstrated the reliability and feasibility of the proposed model, and provided reliable basis for the investment decision-making of prefabricated concrete building projects.
Buildings have become a major concern because of their high energy use and carbon emissions. Thus, a material-efficient prefabricated concrete element (PCE) system was developed to incorporate ...construction and demolition waste as feedstock for residential building energy renovation by over-cladding the walls of old buildings. By conducting life cycle assessment and life cycle costing using the payback approach, this study aims to explore the life cycle performance of energy conservation, carbon mitigation, and cost reduction of the PCE system in three European member states: Spain, the Netherlands, and Sweden. The results show that the energy payback periods for Spain, the Netherlands, and Sweden were 20.45 years, 17.60 years, 19.95 years, respectively, and the carbon payback periods were 23.33 years, 16.78 years, and 8.58 years, respectively. However, the financial payback periods were less likely to be achieved within the building lifetime, revealing that only the Swedish case achieved a payback period within 100 years (83.59 years). Thus, circularity solutions were considered to shorten the PCE payback periods. Using secondary materials in PCE fabrication only slightly reduced the payback period. However, reusing the PCE considerably reduced the energy and carbon payback periods to less than 6 years and 11 years, respectively in all three cases. Regarding cost, reusing the PCE shortened the Swedish payback period to 29.30 years, while the Dutch and Spanish cases achieved investment payback at 42.97 years and 85.68 years, respectively. The results can be extrapolated to support the design of sustainable building elements for energy renovation in Europe.
•Novel technological systems for recycling mineral construction and demolition waste were introduced.•A novel prefabricated concrete element system for renovating existing building (PCE2) was presented.•Comprehensive assessment of the PCE2 system under three EU member states was investigated.•How will material circularity strategies influence the energy-carbon-investment payback of the PCE2 was explored.
Prefabricated concrete building (PCB) can save resources, reduce construction, improve quality, and reduce pollution. Understanding PCB environmental benefits versus traditional buildings could ...reinforce relevant policies and adoption. This study aimed to develop a holistic life-cycle accounting system based on BIM technology to calculate carbon emissions of PCB accurately and efficiently, and verify the effects of energy saving and emission reduction. Existing international and national databanks allowed the compilation of carbon emission factors. Five representative residential PCB projects were enlisted to calculate carbon footprints in six individual life-cycle construction stages. In most stages, carbon emissions were reduced with an increasing prefabrication rate. In the operation and maintenance stage, carbon emissions accounted for approximately 91% of the total, and the building materials production stage accounted for about 11%. The “negative carbon emission” in the demolition and recycling stage was about −4%. Carbon emissions of the remaining three stages were minimal at about < 2%. This study established the whole life-cycle carbon-emission indices of residential prefabricated buildings, with average annual carbon emission per unit area at around 105.88 kgCO2/(m2.a), and computed values for individual building stages. For comparison, a completely cast-in-place building was studied, with average annual carbon emission per unit area at around 130.79 kgCO2/(m2.a), significantly higher than the PCB. The study contributed to knowledge by furnishing the holistic carbon footprint calculation method and establishing the empirical patterns and trends of carbon emissions of PCB. The findings could inform construction projects' carbon-emission control and achieve the construction industry's green and low-carbon goals.
Modern prefabricated building technology can save resources, shorten the construction period, improve quality, and reduce pollution and carbon emissions. This study investigated the carbon footprint ...of prefabricated concrete composite (PCC) plates at the project materialization stage. The joint application of three techniques conducted data analysis and computation: (a) the life cycle assessment (LCA) method providing the overall conceptual framework, building information modeling (BIM) technology designing the PCC-plates and generating the component list, and geographic information system (GIS) software computing the spatial distribution of carbon footprint. A holistic carbon footprint accounting model was established for PCC plates' three materialization substages (component-production, transport-logistics, and construction-installation) to comprehensively evaluate their quantity and distribution of carbon emissions. A detailed case study was conducted to test the proposed method and verify empirical findings. The results indicated: (1) the maximum difference between cases amounted to 92.72 kgCO2/m2; (2) the carbon intensity per unit height was about 18,182.15 kgCO2/m, and the unit cost was about 8469.01 kgCO2/10,000 Yuan; and (3) the prefabrication rate, carbon emission per unit area and per unit cost were significantly correlated, indicating quantitative contributions of using more PCC to carbon footprint reduction. This research can assess the carbon emission of PCC at different construction substages with a good confidence level. The findings can provide a policy reference for the government and the industry to promote and rationalize PCC use and offer the basis to reduce the carbon footprint and sustainability of prefabricated construction.
•Study carbon footprint of prefabricated composite plate PCC at materialization stage.•Build a carbon emission calculation model based on LCA + BIM + GIS.•Devise calculation methods for carbon intensity by unit area, height and cost.•Prefabrication rate, carbon emission per unit area and cost correlated significantly.•Formulate policies and guidelines to integrate PCC into construction projects.
This article presents the development and validation of a design-to-fabrication framework aiming to improve the efficiency of fabricating reinforced concrete building components for housing projects ...in the Kingdom of Saudi Arabia by incorporating 3D concrete printing technology. In particular, the research presents an algorithmic framework to mass customise a typical Saudi Arabian free standing house by utilising parametric modelling, topology optimization (TO), finite element analysis (FEA), and robotic 3D printing tools and techniques. The framework was validated by the fabrication of optimised reinforced concrete columns and by testing their structural performance under the Saudi Building Code (SBC 304). The findings demonstrate the benefits and drawbacks of the proposed framework and compare it to current Saudi conventional construction approaches. The paper also addresses the need for mass customisation in the construction industry of the Kingdom of Saudi Arabia
•Design to fabrication of concrete building components.•Mass customisation of 3D-printing reinforced concrete frame structure.•Topology optimisation of 3D-printing reinforced concrete frame structure.•Validating structural performance of topology optimised column subjected to axial load.•Illustrating the efficiency of 3D printing optimised structural building components, mitigating labour and material waste.
•A replaceable ductile connector with graded yielding is proposed for PC frame joints.•Eleven connector specimens considering different parameters are cyclically tested.•The proposed mechanical model ...is in good agreement with the experimental results.•The deformation behavior is analyzed by numerical models with different parameters.
In conventional reinforced concrete and assembled monolithic concrete frame structures, considerable damage typically occurs in the beam–column joint zone under strong seismic activity. To improve seismic performance and earthquake resilience, a novel replaceable graded-yielding energy-dissipating connector (RGEC) for prefabricated concrete beam–column joints is proposed. In these joints, RGECs are assembled on the upper and lower sides of the beam end. These connectors enable the concentration of plastic deformation on their bending–shear components (BSCs) and buckling segment (BS). Consequently, structural seismic performance can be rapidly restored by replacing the RGECs after an earthquake. An RGEC can realize graded-yielding energy dissipation under earthquakes of different intensities with the successive yielding of BSCs and BS. Mechanical models of the BSC and BS are developed, and a series of tests is performed on 11 specimens. The tests examine the effects of key design factors (such as core plate thickness, width–thickness ratio of the BS, limit gap width, yield stress contour height ratio, and height–width ratio of the BSC) on the seismic behavior of the proposed damper. Results indicate that the RGEC exhibits excellent seismic performance in terms of strength capacity, deformation capacity, energy dissipation capacity, and stiffness degradation. The RGEC can effectively achieve energy dissipation through graded yielding under loads of multilevel intensities. Additionally, based on finite element models validated using available test data, the deformation behavior of the RGEC is analyzed by considering the influences of the yield stress contour height ratio and height–width ratio of the BSC, width–thickness ratio of the BS, and out-of-plane restraint gap width.
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