<p dir="ltr">In recent years (circa 2024), the purpose of pedestrian bridges has extended beyond simply providing a safe route for pedestrians to cross an obstacle. Nowadays, pedestrian bridges are becoming works of art integrated into the design plan for the whole city. The pleasant appearance of these bridges, however, comes at the cost of requiring complex structural analysis and design, unique fabrication requirements, and construction challenges. Therefore, inspecting different types of pedestrian bridges efficiently and adequately is crucial to avoid unexpected failure during their service life. While National Bridge Inspection Standers (NBIS) regulations are only applicable to all publicly owned <i>highway</i> bridges with spans longer than twenty feet, there is no standard inspection criteria applicable across the board for any type of pedestrian bridge (FHWA 2022a). The current criteria, implemented ad-hoc by many owners, is to inspect pedestrian bridges using the traditional calendar-based inspection approach. This method is based on assigning an inspection interval not to exceed some time frame (typically 24-months) for all bridges with exceptions for some specific bridges receiving special inspections. Although this method may provide an adequate level of safety for some bridges, it doesn’t explicitly account for the current condition, variation in operational environment, and the design characteristics of the bridge. In addition, the current inspection practice of pedestrian bridges considers only inspecting bridge's <i>structural conditions</i> while some unique safety and serviceability criteria should be considered to attain an optimum level of safety and serviceability for pedestrians and cyclists on the bridge such as railing, lighting, walking surface, etc.</p><p dir="ltr">The main objective of this research is to develop an inspection criterion specifically applicable to pedestrian bridges to ensure the optimal allocation of inspection resources while maintaining an optimum safety and serviceability. In its final form, the Risk Based Inspection (RBI) methodology is applied in conjunction with reliability concepts and expert inputs from the Risk Assessment Panel (RAP) of the Indiana Department of Transportation (INDOT) to systematically evaluate the key components of the proposed approach. The proposed methodology is based on the Reliability Based Inspection procedures presented in NCHRP 782 report (Washer et al. 2014a). In this method, the inspection interval is determined based on the risk assessment, which is the product of a combination of occurrence and consequence factors. The occurrence factor is calculated based on design, loading (mechanical and environmental), and condition attributes for each type of damage. The consequence factor measures the outcomes of the occurrence of the damage under consideration. This factor is evaluated at two stages, an immediate consequence in which outcomes impact the safety of the service on and under the bridge, and a short-term consequence, in which effects influence the serviceability of the service under the bridge. Furthermore, a new factor is also introduced to the RBI approach. Specifically, what will be referred to as the inspection effectiveness factor which attempts to accounts for the reliability of the inspection technique to identify and quantify a specific defect for a given components of the bridge. The proposed approach is then applied and validated on a set of real in-service pedestrian bridges with varying materials and structural systems. The results demonstrate that the approach improves the safety and serviceability of pedestrian bridge inspections. Furthermore, it ensures a better allocation of the limited inspection resources and proves to be more cost-effective compared to current inspection practices.</p>

The aim of this thesis is to design maintenance work for a small transport aircraft. This thesis is focused on an overview of the activities, which are carried out in the maintenance of small transport aircraft with a capacity about fifty passengers. The first part of this thesis is conceived as a theoretical part and summarizes the activities used during maintenance - maintenance methods, a typical part failures, diagnostics, network analysis and equations for the calculating of the cost of maintenance. At the beginning are showed the basic characteristics of selected representatives of this category and regulatory requirements on them. The design of maintenance work is in the second half of the thesis. It includes the visualization of the database that could be used for the maintenance of aircraft and which could be subsequently evaluated. This is a general description of the maintenance work, which ca be performed during the pre-flight inspection, re-inspection for repeated flights, preliminary preparation and periodic maintenance.