Proposal of a Methodology for Bridge Condition Assessment

Due to the substantial role of bridges in transportation networks and in accordance with the limited funding for bridge management, remediation strategies have to be prioritised. A conservative bridge assessment will result in unnecessary actions, such as costly bridge strengthening or repairs. On the other hand, any bridge maintenance negligence and delayed actions may lead to heavy future costs or degraded assets. The accuracy of decisions developed by any manager or bridge engineer relies on the accuracy of the bridge condition assessment which emanates from visual inspection. Many bridge rating systems are based on a very subjective procedure and are associated with uncertainty and personal bias. The developing condition rating method described herein is an important step in adding more holism and objectivity to the current approaches. Structural importance and material vulnerability are the two main factors that should be considered in the evaluation of element structural index and the causal factor as the representative of age, environment, road class and inspection is implemented as a coefficient to the overall structural index. The Analytical Hierarchy Process (AHP) has been applied to evaluate the priority vector of the causal parameters

Heuristic catenary-based rule of thumbs to find bending moment diagrams

There are numerous nature-inspired curves representing certain structural behaviour being utilised in form-finding process by some famous architects. By closely scrutinising these forms, some interrelated morphological analogies between different structural forms and functions, such as the similarity between free-standing tension-only elements and the shape of bending moment diagram of a beam under the same load condition, can be explored. Most studies in the field of statics principles have only focused on developing numerical and mathematical approaches which are not suitable for practitioners who prefer quick access to the general forms. This paper first gives a brief overview of the most common archi-structural forms through the history of the architecture, and attempts to find the shape of bending moment diagrams through a new simple heuristic method based on drawing an analogy between natural tension-only forms and the diagrams. The purpose of this research is to propose a shortcut to diagram drawing substituting the general time-consuming methods as well as enhance the architects’ perception of bending behaviour of a structural element. A holistic approach is utilised, integrating the natural curves, bending moment diagrams and some rule of thumbs used to define the tapered beam or portal frame general shapes. This simple non-computational method can ease the design process. It will also be useful for educational purposes as well as pre-design phase conception including identification of the critical points of bending elements as well as designing tapered beams and portal frames

Towards eco-flowable concrete production

Environmental concerns have increased due to the amount of unused/expired plastic medical waste generated in hospitals, laboratories, and other healthcare facilities, in addition to the fact that disposing of such wastes with extremely low degradation levels causes them to remain in the environment for extended periods of time. These issues have led researchers to develop more environmentally friendly alternatives for disposing of plastic medical waste in Australia. This study is an attempt to assess the impacts of using expired plastic syringes as fine aggregate on fresh and hardened characteristics of flowable concrete, which might provide a solution to environmental concerns. Six mixtures of flowable concrete with water-to-cement ratios of 0.38 were studied. It was found that using recycled aggregate in up to 20% can improve the workability and increase the V-funnel values of flowable concrete mixtures. However, using waste aggregates in more than 30% caused an inapt flowability. Adding waste aggregate at the 30%–50% replacement level led to a decrease in the L-box ratio. To verify the utility and the efficacy of this experiment, the connections between different rheological test measurements were also compared by implementing the Pearson correlation function. The mechanical properties of the mixes containing recycled aggregates were decreased at the age of seven days; however, at later ages, waste aggregates increased the strength at the 10%–30% replacement levels

Decision Support Systems

The current decision-making problems is more complex than it was in the past, prompting the need for decision support. Most real-world decision-making situations are subject to bounded rationality; whereby the technical and economic evaluation of all solution alternatives (branches) is bounded by the consideration of dominant subjective constraints. The early definition of DSS introduced it as a system that intended to support decision makers in semi-structured problems that could not be completely supported by algorithms. DSSs were planned to be an accessory for managers to expand their capabilities but not to replace them. Decision support systems could provide the means to complement decision makers by quantitatively supporting managerial decisions that could otherwise be based on personal intuition and experience. In addition to the traditional DSS characteristics (i.e., data and model orientation, interactivity), the inclusion of an intelligent knowledge base would be required to quantify the impacts of both technical (hard) and subjective (soft) constraints

Estimating compressive strength of concrete containing untreated coal waste aggregates using ultrasonic pulse velocity

In recent years, the overuse and exploitation of coal resources as fuel in industry has caused many environmental problems as well as changes in the ecosystem. One way to address this issue is to recycle these materials as an alternative to aggregates in concrete. Recently, non-destructive tests have also been considered by the researchers in this field. As there is limited work on the evaluation of the compressive strength of concrete containing coal waste using non-destructive tests, the current study aims to estimate the compressive strength of concrete containing untreated coal waste aggregates using the ultrasonic pulse velocity (UPV) technique as a non-destructive testing approach. For this purpose, various concrete parameters such as the compressive strength and UPV were investigated at different ages of concrete with different volume replacements of coarse and fine aggregates with coal waste. The test results indicate that 5% volume replacement of natural aggregates with untreated coal waste improves the average compressive strength and UPV of the concrete mixes by 6 and 1.2%, respectively. However, these parameters are significantly reduced by increasing the coal waste replacement level up to 25%. Furthermore, a general exponential relationship was established between the compressive strength and the UPV associated with the entire tested concrete specimens with different volume replacement levels of coal waste at different ages. The proposed relationship demonstrates a good correlation with the experimental results

LES analysis on the effects of fire source asymmetry on enhanced wind by fire

Investigation of aerodynamic characteristics of wind enhanced by bushfires is of great significance due to their destructive impacts on buildings located in bushfire-prone areas. Despite the abundance of studies in the fire-wind interaction domain, there have been limited studies concerning the effects of fire on wind aerodynamics. Fire source shape is one of the main factors affecting enhanced wind by fire. This study reports on the effects of fire source asymmetry on aerodynamic changes of wind by fire using a large eddy simulation analysis based on fireFoam solver of OpenFOAM platform. Wind aerodynamic analysis was performed by implementing a module to the solver to extract the corresponding components of fire-induced pressure gradient and acceleration. The results revealed that deviation from fire source symmetry results in asymmetric behaviour of counter-rotating vortices where the maximum cross-sectional wind enhancement occurs. Moreover, the concept of the first-moment area was used to quantify the level of fire source deviation from symmetry and it was shown that the higher first-moment area (about the equivalent symmetry axis) corresponds to a higher deviation from symmetry which delays the realignment of counter-rotating vortices toward the horizontal vortex line

Determining appropriate thermal comfort period based on PET and PMV using the RayMan model : a case study in the subtropical city of Sari

Given the different climate conditions worldwide, the need for climate zone-based architectural designs is evident. This need is more felt, particularly in critical thermal conditions, and is the most important challenge for an architect. One of the main sub-climates that require a special design is the humid subtropical climate in which winters are cold and rainy, and usually, the ambient temperature is lower than the comfort zone, with hot and humid summers that demand a temperature drop to achieve a comfort zone. The most fundamental problem is thus to provide cooling and heating systems in such environments. Accordingly, the present work aims at providing critical climate conditions with potential solutions. Here, Sari, with a humid subtropical climate, was selected as a case study, and its thermal conditions were investigated utilizing Physiological Equivalent Temperature (PET) and Predicted Mean Vote (PMV) indices, and the Rayman model. The results of our first study question revealed that the percentage of days with thermal comfort was 16.9%. Also, 16.3% and 17% of the days had slight and mild cold stress, respectively. Subsequently, the results from data analysis indicated that the ventilation and dehumidification cooling systems can be considered the most appropriate passive methods. In addition, the elements of the indigenous architecture including Iwan, Talaar, upstairs house, and sloping roof, which all are rooted in the vernacular architecture of the city of Sari can be introduced as the most effective architectural solutions. Our findings are of great importance for architects and designers because such findings will guide the design of complex site conditions and even the building construction by considering the thermal comfort factor

A new multi-criteria tie point filtering approach to increase the accuracy of UAV photogrammetry models

Extracting accurate tie points plays an essential role in the accuracy of image orientation in Unmanned Aerial Vehicle (UAV) photogrammetry. In this study, a Multi-Criteria Decision Making (MCDM) automatic filtering method is presented. Based on the quality features of a photogrammetric model, the proposed method works at the level of sparse point cloud to remove low-quality tie points for refining the orientation results. In the proposed algorithm, different factors that affect the quality of tie points are identified. The quality measures are then aggregated by applying MCDM methods and a competency score for each 3D tie point. These scores are employed in an automatic filtering approach that selects a subset of high-quality points which are then used to repeat the bundle adjustment. To evaluate the proposed algorithm, various internal and external studies were conducted on different datasets. The findings suggest that our method is both effective and reliable. In addition, in comparison to the existing filtering techniques, the proposed strategy increases the accuracy of bundle adjustment and dense point cloud generation by about 40% and 70%, respectively

Building a CTU Orientation Handbook iPad® application for first-year residents

Background: The General Internal Medicine Clinical Teaching Unit (CTU) is a challenging rotation for new residents and the optimal format of orientation has not been determined. We hypothesized that an iPad®application (app) would be a useful reference tool after residents completed their traditional large group orientation. Methods: Postgraduate year 1 (PGY1) residents were sent a link to download the free app one week before the start of their rotation. A pre-usage survey at initial login collected basic demographics. Usage data was collected to determine the sections, duration, and the timeframe from which the app was utilized.Results: Pre-usage survey data revealed that 63% of participants were female, 69% felt the app would improve orientation, and 94% were comfortable using mobile technology for medical education. Usage data showed “Teaching Sessions and Schedules,” “The Consult Note,” and “Admission Orders” were the three sections most commonly used. The most usage was during the evening call shift (10pm to 6am), followed by the morning shift (6am to 5pm).   Conclusion: The CTU Orientation App was a useful supplement to the traditional orientation. Researchers may not be able to predict what content would be most valuable in an iPad® app, thus pre-development needs-assessments and usage feedback are crucial.

Numerical analysis of axial cyclic behavior of FRP retrofitted CHS joints

This paper aims to numerically investigate the cyclic behavior of retrofitted and non-retrofitted circular hollow section (CHS) T-joints under axial loading. Different joints with varying ratios of brace to chord radius are studied. The effects of welding process on buckling instability of the joints in compression and the plastic failure in tension are considered. The finite element method is employed for numerical analysis, and the SAC protocol is considered as cyclic loading scheme. The CHS joints are retrofitted with different numbers of Fiber Reinforced Polymer (FRP) layers with varying orientation. The results show that the welding process significantly increases the plastic failure potential. The chord ovalization is the dominant common buckling mode under the compression load. However, it is possible to increase the energy dissipation of the joints by utilizing FRP composite through changing the buckling mode to the brace overall buckling