Current Issue : July-September Volume : 2024 Issue Number : 3 Articles : 5 Articles
The aim of this study is to address challenges encountered in the design of foundation pit support systems for soft soil areas, which include vague calculation methodologies, insufficiently representative parameters, and limited design engineer experience. To address these issues, we conducted a comprehensive review of successful and failed case studies and observed that actual working conditions significantly impact the calculation method of soil and water pressures as well as the selection of representative strength values. Furthermore, we found discrepancies between the current calculation methods for factors such as antiuplift and overall stability and practical applications. When calculating forces like sliding torque and antisliding moment, the choice between using saturated or buoyant gravity can have significant implications. Additionally, we observed that under high pit edge loads, such as 20 kPa, the maximum bending moment in cantilever piles can significantly increase, necessitating stringent limits on these loads. Therefore, in designing foundation pit support systems for soft soil areas, it is essential to consider practical site conditions and lessons learned from previous projects. By selecting appropriate calculation methods and parameters, we can ensure the accuracy and safety of these critical structures....
A cantilever block wall-panel attachment strip (CBW) flexible connection node was designed to connect precast concrete (PC) exterior wall panels to steel frames. To investigate the performance of the CBW flexible connection node and PC exterior wall panels during earthquakes, a partial two-storey steel frame was extracted from an actual engineering structure, and a full-scale steel frame–exterior wall panel shaking-table model was designed. Two sets of shaking-table tests were conducted under seismic intensity 7, 8, and 9 (Chinese Seismic Intensity Scale) earthquakes. The acceleration and displacement responses of the composite wall panel, open window panel, and integral wall panel along the in-plane and out-of-plane motions were analysed. The acceleration amplification factors of the PC exterior wall panels ranged from 0.753 to 1.400 (in-plane) and from 0.998 to 2.199 (out-of-plane). The CBW flexible connection node had a deformation capacity that could coordinate the deformation of the exterior wall panel and prevent severe damage. The surfaces of the PC exterior wall panels remained intact during a very strong seismic intensity 9 earthquake....
The cracking problem of asphalt concrete panels is a crucial consideration in the design of hydraulic asphalt concrete seepage control bodies. Panels experiencing uneven rises or falls of water levels during impoundment may exhibit loading rate effects. Investigating the fracture toughness value of asphalt concrete under varying loading rates is essential. This study employs a statistical method to calculate the fracture index KIC, using the semi-circular bending test (SCB) to examine the effect of loading rates on the Type I fracture mode of hydraulic asphalt concrete. The data are analyzed using the two-parameterWeibull distribution curve, offering insights into the minimum number of KIC test specimens. The results indicate an increase in KIC with loading rate, with greater data dispersion at faster rates. The Weibull distribution curve successfully fits the fracture behavior under different loading rates, providing valuable predictions. This study estimates the minimum number of SCB test specimens to be nine, based on a confidence level of 0.95 and a relative deviation not exceeding 5%....
Contemporary multiscale construction object detection algorithms rely predominantly on fully-supervised deep learning, requiring arduous and time-consuming labeling process. This paper presents a novel semisupervised multiscale construction objects detection (SS-MCOD) by harnessing nearly infinite unlabeled images along with limited labels, achieving more accurate and robust detection results. SS-MCOD uses a deformable convolutional network (DCN)-based teacher-student joint learning framework. DCN uses deformable advantages to extract and fuse multiscale construction object features. The teacher module generates pseudolabels for construction objects in unlabeled images, while the student module learns the location and classification of construction objects in both labeled images and unlabeled images with pseudolabels. Experimental validation using commonly used construction datasets demonstrates the accuracy and generalization performance of SS-MCOD. This research can provide insights for other detection tasks with limited labels in the construction domain....
This paper describes the first results of the application of an innovative methodology for the development of a walkability overall index for urban street infrastructure, aimed at the application of urban design techniques to improve the urban form and its use by pedestrians. The general objective of the research is to identify the performance of the current city walkable network, to structure public policies and strategies consistent with it aimed at rebalancing settlements and infrastructure, and above all at the development of active mobility. The methodology defined integrates three approaches on walkability analysis: geometric–morphological, proximity, and sociality. In this paper, the analysis process related to the geometric–morphological component and partly to that of proximity will be described. It will be applied to the case study of the city of L’Aquila (Italy), a city undergoing reconstruction after the 2009 earthquake. From the first results of the application of the methodology to the case study, it emerges that the urban area analyzed is not capable of hosting walkable infrastructures unless urban design interventions are aimed at structuring an efficient network of pedestrian paths. In the future development of the study, it is expected to conclude the analysis of the proximity and social components, the other two groups of analysis considerations for walkability, which will complete the experimentation of the general methodology....
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