Abstract Additive manufacturing and digital fabrication bring new horizons to concrete and cement-based material construction. 3D printing inspired construction techniques that have recently been developed at laboratory scale for cement-based materials. This study aims to investigate the role of the structural build-up properties of cement-based materials in such a layer by layer construction technique. As construction progresses, the cement-based materials become harder with time. The mechanical strength of the cement-based materials must be sufficient to sustain the weight of the layers subsequently deposited. It follows that the comparison of the mechanical strength, which evolves with time (i.e. structural build-up), with the loading due to layers subsequently deposited, can be expected to provide the optimal rate of layer by layer construction. A theoretical framework has been developed to propose a method of optimization of the building rate, which is experimentally validated in a layer-wise built column.
Baiyu Chen, Matthew J Eckelman, Michelle Laboy
et al.
The construction industry is increasingly focused on reducing embodied carbon emissions to address climate change. Steel—cross laminated timber (CLT) composite hybrid structures, where CLT floors and steel framings work in composite action to resist gravity forces, offers benefits such as carbon storage, recyclability, reduced use of carbon-intensive materials, and improved project schedule and quality control. This composite hybrid system can accelerate progress toward net-zero embodied carbon by integrating carbon-storing materials within the existing AEC (Architecture, Engineering, and Construction) ecosystem for commercial and high-rise buildings, where timber use is limited. This study analyzes two structural patterns within the composite hybrid system and uses life cycle assessment (LCA) to identify trade-offs in embodied carbon. A 12-story office prototype is designed using two framing spans of 12.5 feet (3.8 m, Basic Hybrid ) and 25 feet (7.6 m, Stretch ), resulting in a change in the wood-to-steel ratio. In the Stretch design, the structure’s mass increases by 20% due to thicker CLT panels for the longer span, despite reduced steel framing, resulting in a 5% heavier foundation. The LCA considers upfront emissions from the product and transportation stages (A1–A4). Excluding biogenic carbon, the Stretch design has 3% higher embodied carbon than Basic Hybrid ; however, including biogenic carbon storage shows an 83% greater carbon benefit for Stretch . A dynamic assessment of biogenic carbon storage reveals that the building must be in service for 23 years for forest regrowth to offset initial forestry emissions, while the 7-ply system achieves net-zero carbon for the whole building in 67 years, compared to 80 years for the 5-ply system.
To achieve efficient design and ensure the safety of concrete structures, the use of high-strength concrete, reinforcing steel, and prestressing tendons has been steadily increasing. In this study, for flexural design of prestressed concrete (PSC) structures employing high-strength strands with tensile strengths of 2160 MPa and 2360 MPa, the applicability of the current design-code equation for predicting the strand stress at flexural failure (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>f</mi><mrow><mi>p</mi><mi>s</mi></mrow></msub></mrow></semantics></math></inline-formula>)—which was originally proposed based on studies of conventional strands with tensile strengths of 1860 MPa or lower—was evaluated. Furthermore, an improved prediction equation was proposed. Section analyses based on stress–strain curves obtained from numerous tensile tests of high-strength strands were conducted, and the results were compared with the existing prediction equations specified in ACI 318 and the Korean KDS code. The comparison revealed that, for high-strength strands, the strand stress tends to be underestimated in the tension-controlled region and overestimated in the compression-controlled region. To address these issues, a new prediction equation was proposed that retains the form of the existing equation but incorporates correction factors reflecting the characteristics of high-strength strands. The performance of the proposed equation was evaluated not only for rectangular sections but also for T- and I-shaped sections, and its predictive accuracy was verified by comparing the predicted strand stresses and nominal flexural strengths with those obtained from section analyses. As a result, the proposed prediction equation demonstrated improved accuracy compared with the existing one, while maintaining an appropriate level of conservatism. Therefore, it is expected to enhance design efficiency for PSC structures employing high-strength strands.
Past research has predominantly focused on personality traits and psychological–cognitive factors as isolated predictors of safety behavior, while their interactive effects in shaping safety behavior remain underexplored. The gap constrains mechanistic understanding of safety behavior and limits the effectiveness of individualized interventions. Therefore, this study developed a theoretical framework linking personality traits, psychological–cognitive mediators (safety awareness, safety attitude, safety motivation, subjective norm, and perceived behavioral control) and safety behavior (safety compliance and safety participation). Quantitative data were collected from 431 frontline construction workers and managers using paper-based questionnaires. Structural equation modeling was used to test direct and indirect relationships among variables. The results reveal differentiated psychological–cognitive pathways through which personality traits shape safety behavior. Extraversion suppressed safety compliance through all psychological–cognitive factors except perceived behavioral control, and diminished safety participation via safety attitude and safety motivation. Agreeableness enhanced safety compliance through all psychological–cognitive factors except perceived behavioral control, whereas conscientiousness promoted safety compliance through all mediators. Agreeableness and conscientiousness strengthened safety participation via all mediators except safety awareness. Openness facilitated safety compliance through safety awareness but simultaneously inhibited it through other psychological–cognitive factors, and reduced safety participation via all mediators except safety awareness. Neuroticism undermined safety compliance via safety attitude, safety motivation, and subjective norm, and suppressed safety participation through safety attitude and safety motivation. These findings underscore the critical mediating role of psychological–cognitive factors in personality–safety behavior linkages and offer implications for individualized safety management. Recommended strategies include integrating personality and psychological–cognitive assessments to optimize work allocation and team collaboration, employing immersive and contextualized training to stabilize safety behavior, and developing an artificial intelligence–enabled safety management framework centered on psychological–cognitive regulation.
In the increasingly interconnected contemporary world, there exists an unprecedented demand for architects to possess an awareness of the global diversity and multiplicity of values, cultures, politics and habits. Transnational design studios aim to educate future architects to face this challenge. After exploring collaborative learning in transnational contexts, this research presents two Sino-Italian joint architectural design studios that the authors organised and tutored in 2019. Through on-site observation, semi-structured interviews, self-reflection and a follow-up survey, this research reveals that the universal language of architecture can overcome linguistic barriers in transnational contexts and the collaborative learning atmosphere allows students to learn the advantageous skills from their peers rapidly, particularly in inter-university mixed group learning. This experience significantly enhances the mutual understanding between Chinese and Italian students, not only in terms of design, but also with reference to wider cultural and societal issues. This study contends that establishing transnational design studios is an effective approach to enable future architects to acknowledge unfamiliar contexts and acquire design skills from peer-learning. It allows architects to build upon and understand the fascinating power of diversity in architecture from a young age.
Construction activities of accelerated urbanization in Shenzhen have increased the landslide risk area, which has intensified the potential threat to human and natural environment. However, the risk of landslides in Shenzhen is poorly evaluated. In this article, a landslide risk evaluation (LRE) model is constructed using landslide susceptibility map (LSM) and landslide vulnerability. In the experiment, a stacking ensemble learning (SEL) model is constructed based on convolutional neural network (CNN), multilayer perceptron, gated recurrent unit (GRU), and support vector machine regression to generate LSM by using topography, geology, human engineering activities, time-series precipitation, and time-series normalized difference vegetation index. Road network, building distribution density and annual average precipitation data are used to evaluate landslide vulnerability based on entropy weight method. In this article, multiple statistical indicators are used to evaluate the performance of the LSM model, and Interferometric Synthetic Aperture Radar (InSAR) deformation data are utilized to verify the LRE results in Shenzhen. The results show that the SEL method has more refined results for LSM, with a best overall evaluation accuracy, especially in the receiver operating characteristic curve, where the accuracy is improved by nearly 8%. In LRE of Shenzhen, very high, high, moderate, low, and very low risk areas account for 0.283%, 0.451%, 0.859%, 36.890%, and 61.517%, respectively. In most of very high-risk area, InSAR deformation results show a clear concentrated deformation trend with a large deformation rate. Research results can provide technical and data support for landslide disaster prevention in Shenzhen.
J. Guadalupe Monjardin-Quevedo, Federico Valenzuela-Beltran, Alfredo Reyes-Salazar
et al.
An alternative probabilistic assessment of buildings excited by multi-level seismic loading is presented in this paper. This evaluation is developed for both steel and reinforced concrete buildings using the Performance-Based Seismic Design (PBSD) concept. The methodology implements Probability Density Functions (PDFs) of inter-story drifts to extract structural risk in terms of the reliability index. Ten buildings of steel and reinforced concrete, respectively, are designed considering different locations in Mexico. Then, each structure is excited by ground motions representing different earthquake intensity levels for three performance levels: immediate occupancy, life safety, and collapse prevention. The deterministic seismic response of buildings is extracted using the finite element software OpenSees. Based on the results, it can be stated that the probabilistic assessment technique represents an efficient approach for extracting the seismic risk of structures using PDFs of inter-story drifts. Lastly, it is demonstrated that the evaluation of buildings following PBSD is a step in the right direction, moving from traditional deterministic design concepts to probabilistic philosophies.