Search Results (1,512)

The design and configuration of buildings can play a major role in influencing the environmental impacts of the built environment. This paper explores the relation of building shape and it’s environmental impacts by employing a life cycle assessment (LCA) framework. The primary objective is to contribute to the ongoing discourse on sustainable construction practices by exploring alternatives in office building shapes and heights. The initial focus of our study centers on a set of plan shapes based on different combinations of a 12 × 14 square meter modular unit. This set introduces variations with and without courtyards, coupled with three distinct heights of 3, 6, and 12 m (1, 2, and 4 stories). Expanding our exploration, we introduce a second set of standard geometric shapes, namely square, pentagon, hexagon, heptagon, octagon, and circle. We assess the annual energy demand of buildings with these plan shapes and conduct an LCA analysis focused on the operational energy use stage in the eLCA tool to quantify their environmental implications, focusing on global warming potential (GWP) and primary energy non-renewable total (PENRT) indicators. Through calculations and comparisons of the LCA results, this paper provides insights into the environmental trade-offs and benefits associated with different building plan shapes and heights. Full article

The overarching goal of this research is to evaluate the energy demands and performance of multi-storey cross-laminated timber (CLT) buildings. The research examines the various energy demands influencing the performance of multi-storey CLT buildings. The study addresses the following research question: Can different energy demands influence the performance of CLT buildings? The investigation explores building modeling and simulation under two different weather scenarios to assess these issues. The study considers London Islington and St Albans (Test Reference Year—TRY), due to the proximity of the actual case studies to the reference locations of the weather files. The investigation captures energy demands and performance in the warm season (i.e., May–August). The findings show that the Stadt building (STB) temperatures under the two weather scenarios are warmer by 1.2 °C and 1.6 °C than those of Brid building (BDH) under the same weather conditions. Outdoor dry-bulb temperatures have a lesser impact on radiant temperatures than indoor air temperatures and operative temperatures in the buildings. Solar gains for external windows are influenced by design variables (e.g., building shapes, heights, floor areas, orientations, opening sizes, etc.). The indoor environmental conditions of the buildings under different weather conditions are comfortable, except for BDH St Albans TRY. Occupancy is a major driver influencing domestic hot water (DHW) usage profiles, regardless of the energy sources in the buildings. DHW is a significant parameter determining the overall energy usage in buildings. Other energy usage profiles, such as room electricity, computers and equipment, general lighting, and lighting, can also impact energy usage in buildings. The research outcomes can enhance our understanding of energy usage profiles and possible improvements to enhance the overall performance of CLT buildings. Full article

Precast concrete is an advanced construction technique characterised by high precision, quality, optimisation and is increasingly used in commercial and residential buildings. However, connections between precast elements are often constructed using in-situ casting, which can delay projects and complicate disassembly at the end of a structure’s service life. Dry connections, aligned with the principles of manufacture-to-assemble (MTA), offer a practical and sustainable alternative but present significant challenges regarding seismic performance, particularly in earthquake-prone regions. This study addresses these challenges through a comprehensive parametric numerical investigation into the shear capacity of precast walls with dry connections. Using SeismoStruct 2024 software, more than 340 pushover simulations were conducted to evaluate the influence of various parameters, including concrete compressive strength, axial force percentage, wall section height, overall wall height, and connection characteristics such as bar diameter, quantity, and placement. This research provides critical insights into the combined effects of these parameters, identifying optimal configurations to maximise shear capacity, which is a vital factor for seismic performance. Key findings indicate that shear capacity is significantly enhanced by increasing section height, concrete strength, and axial load, with notable gains such as an 84% improvement in shear strength when section height increased from 2 m to 3 m under favourable conditions. Conversely, increasing overall wall height tended to reduce shear capacity, with a 58% decrease observed for walls extending from 1.5 m to 3.5 m. Adjustments in mechanical connections, including larger diameters, increased bar quantities, and optimised placements, further contributed to incremental improvements in shear strength, with increases ranging from 3% to 24%. Full article

The present paper deals with the asymmetric seismic interaction phenomenon between multistorey reinforced concrete buildings. The paper focuses on the so-called floor-to-column pounding and aims to identify the influence of two specific factors: the exact impact point location and the width of the pre-existing separation gap between the interacting structures. Furthermore, the estimation of the effective impact length, i.e., the part of the external columns directly suffering the hit within their clear height that experiences severe damage, is attempted. For this purpose, several interaction cases are analyzed by means of inelastic dynamic analysis, and representative response quantities are calculated. In addition, a well-documented analytical procedure is applied in order to determine the effective impact length. The whole investigation highlights the crucial role of the impact point location for the local response of the external columns. On the contrary, it demonstrates that the overall building behavior is not considerably affected. In addition, it reveals that the existence of inadequate seismic joints may be more unfavorable in comparison with the complete absence of separation between the interacting structures. Thus, the relevant code provisions imposing a minimum seismic joint width should be strictly abided by. Finally, the investigation confirms field observations and experimental results which indicate that the damage of external columns which undergo strong pounding forces is limited to a short area with length equal to about 1 m or less. Due attention should be given to this area during retrofitting of existing buildings. Full article

Origami-derived space-deployable structures have a broad application prospect in the aerospace field owing to their excellent morphology transformation performance, and they are usually large-scale and lightweight. However, their deformation increases greatly under high-speed and extreme-temperature conditions, which affects their motion and performance and possibly causes losses. So, it is crucial to perform a dynamic analysis considering key factors for the large deformation of flexible structures. In this paper, the Nodal Coordinate-based Floating Frame of Reference (NCFFR) formulation is used to build a rigid–flexible coupling dynamic model of the rotating trapezoidal flexible plate with a Miura angle. NCFFR can not only accurately describe the large deformation of flexible structures but also decouple the overall motion and flexible deformation motion naturally, and it has a potential application in vibration control and large deformation problems for flexible systems. Finally, the key structural parameters (such as Miura angle, trapezoidal plate height, and trapezoidal plate length) are adopted to analyze the dynamic characteristics of the flexible plate system. The simulations reveal that the Miura angle significantly affects the dynamic characteristics of the trapezoidal flexible plate system. The complex “loci veering” phenomenon is captured, with mode shifts between different modal frequencies. As the Miura angle increases, the peak acceleration when the Miura angle is 95° is notably larger than the others, and when the flexible plate is in the stage of uniform rotation, the peak velocity at which the Miura angle is 80° is significantly greater than that of 85° and 75°. The structural parameters (bottom length, height, thickness) have diverse influences on the modal characteristics of the trapezoidal flexible plate. Full article

This paper proposes a steady-state thermal model for the passive cooling of photovoltaic (PV) modules integrated into a vertical building façade by means of a solar chimney, including an empirical correlation for turbulent free convection from a vertical isothermal plate. The proposed analytical model estimates the air velocities at the inlet and at the outlet of the ventilation channel of such a cooling system and the average temperature of the façade-integrated PV modules. A configuration composed of a maximum of six vertically installed PV modules and one solar chimney is considered. The air velocities at the inlet and at the outlet of the ventilation channel obtained for the case of installing PV modules on the building façade are compared with those calculated for the case where the PV modules are integrated into the roof with a slope of 37°. By comparing each of the solutions with one PV module to the corresponding one with six PV modules, it was found that the increase in the air velocity due to the effects of the solar irradiance and the height difference between the two openings of the ventilation channel ranges between 41.05% in the case of “Roof” and 141.14% in the case of “Façade”. In addition, it was obtained that an increase in the solar chimney height of 1 m leads to a decrease in the average PV section temperature by 1.95–7.21% and 0.65–2.92% in the cases of “Roof” and “Façade”, respectively. Finally, the obtained results confirmed that the use of solar chimneys for passive cooling of façade-integrated PV modules is technically justified. Full article

The Betz constant is the well-known aerodynamic limit of the maximum power which can be extracted from wind using wind turbine technologies, under the assumption that the wind speed is uniform across a blade disk. However, this condition may not hold for large wind turbines, since the wind speed may not be constant along their height; rather, it may vary with the location due to surface friction from tall buildings and trees, the topography of the Earth’s surface, and radiative heating and cooling in a 24 h cycle. This paper derives a new power coefficient for large wind turbines based on the power law exponent model of the wind gradient and height. The proposed power coefficient is a function of the size of the rotor disk and the Hellmann exponent, which describes the wind gradient based on wind stability at various locations, and it approaches the same value as the Betz limit for wind turbines with small rotor disks. It is shown that for large offshore wind turbines, the power coefficient was about 1.27% smaller than that predicted by the Betz limit, whereas for onshore turbines in human-inhabited areas with stable air, the power coefficient was about 8.7% larger. Our results are significant in two ways. First, we achieve generalization of the well-known Betz limit through elimination of the assumption of a constant wind speed across the blade disk, which does not hold for large wind turbines. Second, since the power coefficient depends on the location and air stability, this study offers guidelines for wind power companies regarding site selection for the installation of new wind turbines, potentially achieving greater energy efficiency than that predicted by the Betz limit. Full article

Lidar technology is pivotal for detecting and monitoring the atmospheric environment. However, maintaining optical path stability in complex environments poses significant challenges, especially regarding adaptability and cost efficiency. This study proposes a tunable optical alignment method that is applied to the Rotating Rayleigh Doppler Wind Lidar (RRDWL) to enable precise detection of mid-to-upper atmospheric wind fields. Building on the conventional echo signal strength method, this approach calibrates the signal strength using cloud information and the signal-to-noise ratio (SNR), enabling stratified and tunable optical alignment. Experimental results indicate that the optimized RRDWL achieves a maximum detection height increase from 42 km to nearly 51 km. Additionally, the average horizontal wind speed error at 30 km decreases from 11.3 m/s to 4.4 m/s, with a minimum error of approximately 1 m/s. These findings confirm that the proposed method enhances the effectiveness and reliability of the Lidar system under complex operational and diverse weather conditions. Furthermore, it improves detection performance and provides robust support for applications in related fields. Full article

The accurate prediction of heat demand in retrofitted residential buildings is crucial for optimizing energy consumption, minimizing unnecessary losses, and ensuring the efficient operation of heating systems, thereby contributing to significant energy savings and sustainability. Within the framework of this article, the dependence of the energy consumption of a thermo-modernized building on a chosen set of climatic factors has been meticulously analyzed. Polynomial fitting functions were derived to describe these dependencies. Subsequent analyses focused on predicting heating demand using artificial neural networks (ANN) were adopted by incorporating a comprehensive set of climatic data such as outdoor temperature; humidity and enthalpy of outdoor air; wind speed, gusts, and direction; direct, diffuse, and total radiation; the amount of precipitation, the height of the boundary layer, and weather forecasts up to 6 h ahead. Two types of networks were analyzed: with and without temperature forecast. The study highlights the strong influence of outdoor air temperature and enthalpy on heating energy demand, effectively modeled by third-degree polynomial functions with R² values of 0.7443 and 0.6711. Insolation (0–800 W/m²) and wind speeds (0–40 km/h) significantly impact energy demand, while wind direction is statistically insignificant. ANN demonstrates high accuracy in predicting heat demand for retrofitted buildings, with R² values of 0.8967 (without temperature forecasts) and 0.8968 (with forecasts), indicating minimal performance gain from the forecasted data. Sensitivity analysis reveals outdoor temperature, solar radiation, and enthalpy of outdoor air as critical inputs. Full article

Despite extensive research on the performance of Oscillating Water Columns (OWC) over the years, issues with low energy conversion efficiency and unstable power generation have not been addressed. In this study, a novel OWC energy conversion system is proposed based on the working principle of energy storage valve control. The system utilizes accumulators and valve groups to enhance the stability of energy conversion. The hydrodynamic model of the OWC system and the pneumatic model of the novel power take-off (PTO) system are developed using numerical simulations. Building on this, the impact of the incident wave period, wave height, and air chamber opening ratio on the system’s total hydrodynamic performance are examined. The results from the hydrodynamic analysis are subsequently used as input conditions to evaluate the proposed PTO system’s performance. The results show that the hydrodynamic efficiency of the system presents a tendency to increase and then decrease with the increase in the incident wave period, and an optimal period exists. The air chamber opening ratio has a notable influence on the hydrodynamic characteristics of the OWC system, and the larger system damping could be set to achieve a higher capture efficiency in the low-frequency water environment. The incident wave height has a lesser effect on the hydrodynamic characteristics and the resonant period of the device. The designed novel PTO system can effectively improve the energy conversion stability of the OWC device, the flow volatility through the turbine can be reduced by 53.49%, and the output power volatility can be reduced by 25.46% compared with the conventional PTO system. Full article

China has an existing building area of 80 billion square meters, where reinforced concrete structures have a large quantity and a wide surface area. The risk of structures being subjected to blast loading is relatively high. Reactive powder concrete has the specialties of ultra-high toughness, super strength, and a high strength to ponderance ratio. Reinforced concrete (RC) structures strengthened by RPC are called RPC-RC structures, which can easily elevate the explosive load resistance of building structures while also strengthening the building. It is a significant method used in avoiding the collapse of structures under explosive loads. The dynamic reaction and damage evaluation approaches of RPC-RC columns under explosive load have not been deeply studied. For addressing this issue, numerical simulation of RPC strengthened RC columns under explosive load was carried out by LS-DYNA (R10), and the correctness of the numerical simulation was verified by comparing it with relevant experimental results. In this paper, a finite element model of an RPC-RC column was established, and the main factors affecting the anti-explosion performance of an RPC-RC column were studied. The influence of the RPC reinforcement layer parameters (RPC thickness, RPC strength, longitudinal reinforcement ratio, and stirrup ratio) on the dynamic reaction and damage degree of RPC-RC columns was examined. The consequences indicated that the failure mode of the columns after RPC reinforcement can alter from bending shear damage to bending damage. As the thickness and strength of the RPC increases, the longitudinal reinforcement ratio increases, the stirrup ratio increases, and the maximum horizontal deformation of the center point of the RPC reinforced RC columns decreases. For RPC-RC columns with a height of 3–4 m and a width of 300–400 mm under blast loading, columns with an axial compression ratio greater than 0.3 will collapse, while columns with an axial compression ratio less than 0.3 are less likely to collapse. In the light of the calculation outcomes, a formula for reckoning the damage index of RPC-RC columns was proposed, taking into account factors such as proportional distance, axial compression ratio, RPC thickness, longitudinal reinforcement ratio, and stirrup ratio. Full article

A comfortable outdoor environment, like its indoor counterpart, can significantly enhance the quality of life and improve the physical and mental health of elderly populations. Urban spatial morphology is one of the key factors influencing outdoor environmental performance. To explore the interactions between urban spatial morphology and the outdoor environment for the elderly, this study utilized parametric tools to establish a performance-driven workflow based on a “morphology generation–performance evaluation–morphology optimization” framework. Using survey data from 340 elderly neighborhoods in Beijing, a parametric urban morphology generation model was constructed. The following three optimization objectives were set: maximizing the winter pedestrian Universal Thermal Climate Index (UTCI), minimizing the summer pedestrian UTCI, and maximizing sunlight hours. Multi-objective optimization was conducted using a genetic algorithm, generating a “morphology–performance” dataset. Subsequently, the XGBoost (eXtreme Gradient Boosting) and SHAP (Shapley Additive Explanations) explainable machine learning algorithms were applied to uncover the nonlinear relationships among variables. The results indicate that optimizing spatial morphology significantly enhances environmental performance. For the summer elderly UTCI, the contributing morphological indicators include the Shape Coefficient (SC), Standard Deviation of Building Area (SA), and Deviation of Building Volume (SV), while the inhibitory indicators include the average building height (AH), Average Building Volume (AV), Mean Building Area (MA), and floor–area ratio (FAR). For the winter elderly UTCI, the contributing indicators include the AH, Volume–Area Ratio (VAR), and FAR, while the inhibitory indicators include the SC and porosity (PO). The morphological indicators contributing to sunlight hours are not clearly identified in the model, but the inhibitory indicators for sunlight hours include the AH, MA, and FAR. This study identifies the morphological indicators influencing environmental performance and provides early-stage design strategies for age-friendly neighborhood layouts, reducing the cost of later-stage environmental performance optimization. Full article

Crawler cranes are mobile lifting equipment used in the process of hoisting goods. After the initial lifting, the crane may need a secondary lift due to adjustments in the position or height of the load. Addressing the common issue of load slipping during the secondary lift caused by hydraulic motor reversal, this study proposes a control strategy applicable to crawler crane secondary lifting. Initially establishing the dynamic characteristics of the secondary lift system, incorporating a delay coefficient, and matching motor pressure build-up with memory pressure, the strategy considers a variable pump input current control to identify the relationship between motor pressure build-up and brake release. Analyzing the dynamic characteristics of secondary lifting under different conditions, this study resolves the issue of hydraulic motor reversal during the second lift caused by heavy loads. The results of this study on crawler crane secondary lifting indicate that, when using a delay coefficient of 0.70 and releasing the brake, no slip phenomenon occurred during the secondary lift process under different load conditions, categorized as 200 tons, 600 tons, and 1000 tons. This ensures the stability and transition quality of the secondary lift, providing theoretical guidance for the control of the crawler crane secondary lifting. Full article

Surface properties in complex urban environments can significantly impact local-level temperature gradients and distribution on several scales. Studying temperature anomalies and identifying heat pockets in urban settings is challenging. Limited high-resolution datasets are available that do not translate into an accurate assessment of near-surface temperature. This study developed a model to predict land surface temperature (LST) at a high spatial–temporal resolution in urban areas using Landsat data and meteorological inputs from NLDAS. This study developed an urban microclimate (UC) model to predict air temperature at high spatial–temporal resolution for inner urban areas through a land surface and build-up scheme. The innovative aspect of the model is the inclusion of micro-features in land use characteristics, which incorporate surface types, urban vegetation, building density and heights, short wave radiation, and relative humidity. Statistical models, including the Generalized Additive Model (GAM) and spatial autoregression (SAR), were developed to predict land surface temperature (LST) based on surface characteristics and weather parameters. The model was applied to urban microclimates in densely populated regions, focusing on Manhattan and New York City. The results indicated that the SAR model performed better (R² = 0.85, RMSE = 0.736) in predicting micro-scale LST variations compared to the GAM (R² = 0.39, RMSE = 1.203) and validated the accuracy of the LST prediction model with R² ranging from 0.79 to 0.95. Full article

With growing worldwide interest in constructing larger and taller wooden buildings, wood properties, such as the dynamic modulus of elasticity (${MOE}_{dyn}$), have become increasingly important. However, the ${MOE}_{dyn}$ of trees and logs has rarely been considered in forest management because a method for estimating the ${MOE}_{dyn}$ of logs based on standing tree characteristics has been lacking. Herein, we explored the multiple relationships between the ${MOE}_{dyn}$ of logs and standing tree characteristics of Japanese cedar (Cryptomeria japonica) such as tree height, diameter at breast height (DBH), and tree age, including the stress-wave velocity of the tree, which is known to be correlated with the ${MOE}_{dyn}$ of logs. The relationship between the ${MOE}_{dyn}$ of logs and standing tree characteristics was investigated by considering the bucking position. Different trends between the bottom logs and upper logs were found for all characteristics, showing a multiple trend of tree characteristics with the ${MOE}_{dyn}$ of logs based on the bucking position. The top three generalised linear mixed models for the prediction of the ${MOE}_{dyn}$ of logs showed relatively high accuracies when the bucking position was considered as a random effect. Although the contribution of the stress-wave velocity of the tree was relatively high, adding tree age improved the accuracy of the model, and this model was selected as the top model. The model for the bottom log, utilising the stress-wave velocity and age of the tree as explanatory variables, was highly explanatory (R² = 0.70); however, the best model for upper logs was only moderately explanatory (R² = 0.44). In addition, tree height and DBH were selected as explanatory variables along with tree age in the second and third models, which suggested the importance of growth rate rather than tree size. Therefore, adding correlates associated to characteristics related to height growth, such as site index, and DBH growth, such as stand density, is expected to improve model accuracy. Full article