KSCE Journal of Civil Engineering最新文献

The escalating concern regarding irreversible environmental damage has stimulated a global interest in sustainable transportation systems. Green transportation, as a sub-branch of sustainable transportation, aims to enhance economic empowerment of governing bodies, promote active utilization of natural resources, minimize emissions, safeguard the environment, and foster cleaner surroundings. This paper presents a methodology for assessing and comparing countries in terms of sustainable and green transportation using the multi-criteria decision-making method (MCDM). The dataset employed for the analysis comprises three primary criteria: environment, transportation, and economy, further divided into eight sub-criteria, encompassing population, air quality, greenhouse gas emissions, number of motor vehicles, number of electric vehicles, bicycle usage, share of renewable energy sources, and gross domestic product. The Analytical Hierarchy Process (AHP) is employed to weigh these criteria, followed by ranking countries through the Multi-Objective Optimization on the basis of the Ratio Analysis (MOORA) method. The findings reveal that Holland secures the top rank, while Türkiye ranks last concerning sustainable and green transportation. Based on the comparative results, it is recommended that countries positioned lower in the list can improve their standing by prioritizing various parameters such as bicycle transportation, pedestrian-friendly measures, eco-friendly vehicles, public transportation, energy conservation, and economic strength.

The four-point loading tests of polyvinyl alcohol fiber-reinforced recycled aggregate concrete (PVAF-RRAC) slabs are conducted and the impacts of reinforcement ratio ρ_s, content of PVA fiber ρ_f, span-thickness ratio l/h and replacement ratio of recycled coarse aggregate (RCA) γ on crack formation mechanism, crack spacing and crack width are analyzed. The failure modes of recycled aggregate concrete (RAC) slabs and PVAF-RRAC slabs are distinguished by yield of longitudinal tensile reinforcement and fragmentation of concrete in compression zone. Meanwhile, the damage of PVAF-RRAC slabs is also accompanied by pull-out or broken of PVA fibers along crack gaps. In contrast, the concrete crushing phenomenon of PVAF-RRAC slabs is not distinct, indicating PVA fibers incorporation could improve flexural performance. The average spacing and maximum crack width of PVAF-RRAC slabs are relatively small, the crack distribution is more uniform. The crack development rate and crack width decrease as ρ_f or ρ_s increases while they increase as γ or l/h increases. Considering the impact of ρ_f on average crack spacing, a formula for approximately forecasting the average crack spacing of PVAF-RRAC slabs is proposed. Additionally, an influence coefficient of RCA is introduced, a prediction model for crack width in PVAF-RRAC slabs is established and test data are validated with favorable results.

This paper presents an innovative seismic isolation system for the structure and unbounded rubber soil. The dynamic interaction of the rubber soil and structure is considered. The rubber soil mixture is constituted by rubber particles and clay. The pollution problem of wast rubber is solved effectively. The rubber soil is firstly introduced into the ordinary unbounded foundation. According to the composite material theory and hybrid law, the rubber soil modulus formulation is derived by two-phase modulus innovatively. By employing the standard viscous boundary method, the radiation damping of unbounded rubber soil is considered. And then, the novel wave propagation equation of unbounded rubber soil is derived. Based on the cylindrical expansion wave and cut-off wave assumptions, the normal and tangential boundary condition equations are derived, respectively. The interaction force causing by earthquake on the rubber soil and structure is modeled. Numerical examples are presented to demonstrate the effectiveness and reliability of the proposed method for the rubber soil and structure interaction model. The seismic response of the rubber soil and structure system is discussed. Excellent seismic performance of rubber soil is confirmed. The influence of the rubber soil content and thickness are discussed in detail.

Megaprojects need to be developed in a socially responsible manner as they may otherwise, like some mega water transfer (MWT) projects, cause ecological damage, environmental pollution, labor conflict, and other problems. Socially responsible collective action (SRCA) can be measured through intentions to take collective action (internal driving mechanisms) and behaviors to engage in collective action (external driving mechanisms). This research aims to develop and validate a network governance model to explore how SRCA, in the context of MWT projects, is enhanced. Data were collected from 365 respondents involved in MWT projects via an online survey. System dynamics (SD) was used to establish the system flow diagram model. Thereafter, Vensim PLE software was used to perform simulation and sensitivity analyses of the model. The results demonstrate that the network governance model explains how to enhance the SRCA of stakeholders in MWT projects. The main findings indicate that external driving mechanisms positively impact the SRCA during the entire project lifecycle, with values fluctuating around the initial level from the early to the mid-late stages, with small fluctuation. Internal driving mechanisms also positively impact SRCA, with values continuously increasing from the early to the mid-late stage.

With tidal traffic becoming an important feature of urban transportation, the impact of tidal lanes on traffic flow is a research topic for many scholars. This paper explores the setting scheme of tidal lanes at toll stations based on the conditions and rules for setting up tidal lanes on urban roads. A highway tidal toll station model is established based on VISSIM. The traffic flow characteristics are simulated when the main traffic flow directions in tidal traffic are located at the exit and entrance of the toll station, respectively. We use a tidal coefficient of 0.7 as an example to analyze the impact of the switching ratio of tidal lanes at toll stations on the traffic volume in the exit and entrance directions under different traffic flow states. We determine the optimal number of tidal lanes to open through analysis of traffic growth rate and total traffic volume changes at toll stations, and propose an opening model for tidal lanes at toll stations under different tidal traffic flow states. In addition, we take the Jingxiong Highway in China as an example to design the traffic organization of the tidal lane, which provides reference for the control of tidal toll stations.

This study investigates the influence of various transverse reinforcement configurations on the torsional performance of glass fiber reinforced plastic (GFRP) reinforced concrete beams. A comprehensive experimental investigation includes five specimens, each characterized by unique transverse reinforcement designs in terms of stirrup spacing and inclination angles. The implementation of transverse torsional reinforcements within the beams exhibited a remarkable post-cracking hardening response, contributing to enhanced strength recovery. The experimental findings are subsequently compared with a reliable three-dimensional finite element model developed using the ABAQUS software. Finally, a parametric study is conducted to examine the influence of concrete and GFRP bar strength, along with longitudinal and transverse reinforcement ratios, on the torsional behavior of GFRP reinforced concrete beams. The results emphasize the significant impact of concrete tensile strength and transverse reinforcement on the cracking torque, while the parameters related to longitudinal reinforcement have only marginal effects.

Quick and accurate identification of bridge damage after an earthquake is crucial for emergency decision-making and post-disaster rehabilitation. The maturing technology of deep neural networks (DNN) and the integration of health monitoring systems provide a viable solution for seismic damage identification in bridges. However, how to construct damage features that can efficiently characterize the seismic damage of the bridge and are suitable for the use with DNN needs further investigation. This study focuses on seismic damage identification for a continuous rigid bridge using raw acceleration responses, statistical features, frequency features, and time-frequency features as inputs, with damage states as outputs, employing a deep convolutional neural network (CNN) for pattern classification. Results indicate that all four damage features can identify seismic damage, with time-frequency features achieving the highest accuracy but having a complex construction process. Frequency features also demonstrate high accuracy with simpler construction. Raw acceleration response and statistical features perform poorly, with statistical features deemed unsuitable as damage indicators. Overall, frequency features are recommended as CNN inputs for quick and accurate bridge seismic damage identification.

The formation by trucks equipped with connected and autonomous driving technology reduces the fuel consumption of vehicles and increases transport efficiency. This study focuses on highway freight trucks, and the functions of fuel cost and time cost were established based on vehicle dynamics theory and transportation economics. A platoon benefit function was developed combined with the functions of fuel cost time cost. Subsequently, an optimization model for the catch-up speed during the platooning process was established. To analyze the effects of the speed of vehicles and formations on the optimal catch-up speed, a transportation from Changchun to Shenyang in China was used as a case study, and the impacts of air resistance variation coefficient and distance between vehicle and formation on platoon benefits were discussed. The results indicate that the platoon benefit decreases by 16.49% when the distance between vehicle and formation increases from 0.2 km to 5 km, and the benefit decreases by 64.87% when the in-platoon air resistance variation coefficient increases from 0.6 to 0.95, which demonstrates that joining a closer platoon will yield greater benefits when multiple formations are available. Furthermore, a lower in-platoon air resistance variation coefficient increases the likelihood of joining that platoon.

In order to study the mechanical behavior of U-rib internal welding of orthotropic plate, the three-dimensional thermal coupling model of U-rib of orthotropic plate was established by using ABAQUS finite element software, and the structural stress distribution law of welded joints in three groups of welded joints was analyzed in four kinds of loading conditions by taking into consideration of the presence of weld toe on the inner side, different sizes of weld toe on the inner side, and different welding melt depths. The results show that the structural stress distribution law of single-sided welding and double-sided welding is the same, the structural stress of the outer weld toe of the bridge deck plate and the outer weld toe of the U-rib is more than 80 MPa under unfavorable working conditions, and the cracking chance is the greatest, the change of melting depth has the greatest influence on the structural stress of the outer weld, and the setting of inner welding can effectively improve the structural stress and improve the welding quality.

The effect of direct fire on flexural behavior of small-scale fiber reinforced concrete beams under sustained loading has been studies through an experimental investigation. A mix of synthetic polypropylene structural macro and micro fibers has been used to obtain the effect of mixed fiber dosage on bearing capacity of simply supported beam under direct flame at its bottom face. The load-deflection, temperature gradient, spalling and durability time until collapse has been recorded and compared in different conditions. In order to know the effect of load level, the tests have been performed for 40% and 70% of the ultimate member capacity at normal temperature. Based on obtained test results, the use of macro synthetic fibers can increase the flexural ductility more than 50% and the durability time until failure up to 27%. The post fire behavior curves of all samples at the cooling phase have also been checked until the beam failure has been occurred including the weight losses due to spalling for both heating and cooling phases. A comparison with the results of conventional post fire loading tests on cooled samples showed that the results can be underestimated about 1.5 times compared to the direct fire test. It has also been shown that the level of sustained load directly affects the capacity, durability and ductility while the increase in the number of fibers do not necessarily improve the behavior in the same manner.