Non-destructive testing (NDT) methods are typically utilized to thoroughly inspect existing defects in the concrete bridge deck and tackle the limitations of common inspection practices (e.g., visual inspection). Nevertheless, the reliability of inspection outcomes crucially depends on choosing the most appropriate NDT technologies. In this regard, a comprehensive Performance Assessment Model (PAM) was developed. The developed model incorporated 40 parameters to precisely assess the performance of different NDT technologies from diverse perspectives (e.g., defect detection capability, ease of use, speed, and cost). The required data were collected through a survey questionnaire. The model utilized the Analytic Network Process (ANP) technique to calculate the importance weight of each parameter, whereas the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was exploited to compute the performance index (PI) of NDT technologies. The outcomes of this study clearly illustrate the disparity in the performance of different NDT technologies. Furthermore, it was shown that none of these technologies could either exhibit the best performance in all the proposed parameters or efficiently identify all types of defects. Based on the PAM results, a selection model was proposed to assist bridge authorities and consultants in choosing the most efficient NDT technologies for inspection purposes.
Plunge milling is an effective roughing operation, especially in pockets roughing, because it can efficiently remove a large amount of stock material without high manufac turing costs. However, plunge milling o f complex pockets with islands, whose boundaries could be designed with free-form curves, is quite challenging for multiple plungers have to be used including small plungers to cut necks between islands and their plungers paths are expected to have fewer times of plunging and shorter travel to achieve efficient machining. Unfortunately, little research on this topic was carried out in the past, and the challenge has not been addressed yet. In this research, a new approach is proposed to generate plunger paths for efficient plunge milling of the complex pockets. Its main features include (1) packing plunger circles at a minimum number of locations inside the pocket for fewer times of plunging, (2) placing plunger circles to cover the areas enclosed by the afore-packed circles to clear out the interior pocket material, and (3) planning the shortest paths to connect plunger locations for less traveling time. The advantages of this new approach over the overlapped circles filling (OCfill) and the Catia methods are dem onstrated with two examples, and it can be directly used for pocket plunge milling in industry.
Off-site construction (OSC) is an innovative construction method that transfers most of the site-based work to a more controlled environment. Construction waste minimization, speedy schedules, higher sustainability, and better quality are some of the perceived benefits of OSC. Therefore, significant research attention has been given to OSC. However, minimal research attention has been given to procurement management in OSC, which could impact its pace of adoption. Existing studies on the procurement methods of OSC projects have overlooked several criteria related to OSC that impact the selection of the appropriate procurement methods (i.e., design-build, construction management, etc.). In addition, the literature lacks decision-making tools to assist OSC practitioners in selecting the appropriate procurement method. In this regard, this study contributes to the body of knowledge by (1) identifying the criteria that impact the selection of OSC procurement methods; (2) developing a multi-criteria decision-making (MCDM) model to select the appropriate OSC procurement methods. The developed MCDM model uses a hybrid approach of analytic network process (ANP) and evidential reasoning (ER). The ANP, which considers the interdependencies among the collected OSC procurement criteria, is used to calculate the relative importance weights through questionnaire surveys. The ER method evaluates various OSC procurement methods in accordance with the criteria importance weights. The results indicate that project quality, cost control, and funding arrangement are the prominent selection factors. On the other hand, the model reveals that the integrated project delivery (IPD) and construction management (CM) methods have the highest utility scores. The MCDM model has been validated by comparing the results with similar studies. The present study could assist OSC practitioners in selecting the appropriate procurement method for OSC projects.
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