Application of UAVs for assessment of bridge infrastructure

The shortcomings of classical methods for inspection of transport infrastructure objects have led to the development of more efficient, more reliable, faster and cheaper procedures for condition assessment and load-bearing capacity and service life estimation of objects. In this context, different autonomous systems developed in the last decade have the most notable role and their development is continuously speeding up. This paper provides a state of the art review of the unmanned aerial vehicles application for structural inspection with a focus on bridges. The paper comprises the following: a review of the current regulations prescribing the types and frequency of inspections; a review of the current classical inspection methods with their advantages and disadvantages; analysis of advantages and disadvantages in application of unmanned aerial vehicles for bridge inspections and a review of the equipment commonly used in their development.

Determination of Local Stresses and Strains within the Notch Strain Approach: Efficient Implementation of Notch Root Approximations

An estimation of the elastic-plastic stress state using elasticity-theoretical input data is an essential part of the service life estimation with the local strain approach in general and a German guideline based on it, in particular. This guideline uses two different notch root approximations (an extended version of Neuber’s rule and an approach according to Seeger and Beste) for this estimation. Both require the implementation of Newton’s method to be iteratively solved. However, many options are left open to the user concerning implementation in program code. This paper discusses ways in which notch root approximation methods can be implemented efficiently for use in software systems and elaborates an application recommendation. The following aspects and their influence on the computational accuracy and performance of Newton’s method are considered in detail: influence of the formulation of the root finding problem, determination of the derivative required for Newton’s method and influence of the termination criterion. The investigation shows that the advice given in the abovementioned guideline indeed leads to a conservative implementation. By carefully considering the investigated aspects, however, the computational performance can be increased by approximately a factor of 2–3 without influencing the accuracy of the service life estimation.

Residual service life estimation of bridges

<p>While concrete structures perform well in many situations, lack of durability has emerged as a significant issue for asset owners. A review of past bridge failures was done to identify the most probable causes of bridge failures. This study has tended to focus on current models used for estimating the time to deterioration of concrete bridges instigated by Chloride ingress and Fatigue. Subsequently, mathematical modelling of the best-suited deterioration model is done to arrive at the residual life of two existing bridges. This work has highlighted high variability in the parameters used to describe the durability related properties of in-situ aged concrete. A realistic residual life assessment can be achieved by correct evaluation of these parameters by periodic testing of bridge samples</p>

An investigation of the airport pavement management system (APMS)

The research aims to discuss and investigate the process of airport pavement management system (APMS). The methodology of the research is based on previous studies that describe the major elements of the APMS to gain more solutions from the previous different case studies. The investigate includes various subjects such as components and cost approach of the APMS. The methodology used in the research is a descriptive method based on previous studies and from different books by using pavement management system (PMS). The study describes the typical distress types of the asphalt-surfaced pavements and the Portland cement concrete pavements of airports. Additionally, the research clarifies the test methods of the airport pavement, such as the ASTM D5340 and ASTM D6433. Research investigates that the software used in the APMS like PAVER and Road-SIT, Airport PMS that are used by the airport agencies to collect information about the situation of the runway pavement. The APMS still needs more research and new studies due to a lack of information and studies in different airports around the world. The airports shall use the service life estimation (SLT) for the pavement in the runways and parking. In recent studies, the method is not used, whereas including a quantitative methodology which demonstrates results to facilitate the clarity of the results to illustrate the advantage of the SLT.