Search results

Purpose – The purpose of this study is to develop a numerical framework to predict the time-dependent probability of failure of a bridge subjected to multiple vehicle impacts. Specially, this study focuses on investigating the inter-relationship between changes in life-cycle parameters (e.g., damage size caused by vehicle impact, loss of initial structural capacity, and threshold intervention) and bridges probability of failure.

Design/Methodology/Approach – The numerical procedure using MATLAB program is developed to compute the probability failure of a bridge. First, the importance and characteristics of life-cycle analysis is described. Then, model for damage accumulation and life cycle as a result of heavy vehicle impacts is discussed. Finally, the probability of failure of a bridge subjected to vehicle impacts as a result of change in life-cycle parameters is presented.

Findings – The results of study show that damage size caused by both vehicle impacts and loss of initial structural capacity have a great impact on the long-term safety of bridges. In addition, the probability of failure of a bridge under different threshold limits indicates that the structural intervention (e.g., repair or maintenance) should be undertaken to extend the service life of a bridge.

Research Limitations/Implications – The damage sizes caused by heavy vehicle impacts are based on simple assumptions. It is suggested that there would be a further study to estimate the magnitude of bridge damage as a result of vehicle impact using the full-scale impact test or computational simulation.

Practical Implications – This will allow much better predictions for residual life of bridges which could potentially be used to support decisions on health and maintenance of bridges.

Originality/Value – The life-cycle performance for assessing the time-dependent probability of failure of bridges subjected to multiple vehicle impact has not been fully discussed so far.

This paper covers the development of a novel defect model for concrete highway bridges. The proposed defect model is intended to facilitate the identification of bridge’s condition information (i.e. defects), improve the efficiency and accuracy of bridge inspections by supporting practitioners and even machines with digitalised expert knowledge, and ultimately automate the process.

The research design consists of three major phases so as to (1) categorise common defect with regard to physical entities (i.e. bridge element), (2) establish internal relationships among those defects and (3) relate defects to their properties and potential causes. A mixed-method research approach, which includes a comprehensive literature review, focus groups and case studies, was employed to develop and validate the proposed defect model.

The data collected through the literature and focus groups were analysed and knowledge were extracted to form the novel defect model. The defect model was then validated and further calibrated through case study. Inspection reports of nearly 300 bridges in China were collected and analysed. The study uncovered the relationships between defects and a variety of inspection-related elements and represented in the form of an accessible, digitalised and user-friendly knowledge model.

The contribution of this paper is the development of a defect model that can assist inexperienced practitioners and even machines in the near future to conduct inspection tasks. For one, the proposed defect model can standardise the data collection process of bridge inspection, including the identification of defects and documentation of their vital properties, paving the path for the automation in subsequent stages (e.g. condition evaluation). For another, by retrieving rich experience and expert knowledge which have long been reserved and inherited in the industrial sector, the inspection efficiency and accuracy can be considerably improved.

The long-span continuous rigid-frame bridges are commonly constructed by the section-by-section symmetrical balance suspension casting method. The deflection of these bridges is increasing over time. Wet joints are a typical construction feature of continuous rigid-frame bridges and will affect their integrity. To investigate the sensitivity of shear surface quality on the mechanical properties of long-span prestressed continuous rigid-frame bridges, a large serviced bridge is selected for analysis.

Its shear surface is examined and classified using the damage measuring method, and four levels are determined statistically based on the core sample integrity, cracking length and cracking depth. Based on the shear-friction theory of the shear surface, a 3D solid element-based finite element model of the selected bridge is established, taking into account factors such as damage location, damage number and damage of the shear surface. The simulated results on the stress distribution of the local segment, the shear surface opening and the beam deflection are extracted and analyzed.

The findings indicate that the main factors affecting the ultimate shear stress and shear strength of the shear surface are size, shear reinforcements, normal stress and friction performance of the shear surface. The connection strength of a single or a few shear surfaces decreases but with little effect on the local stress. Cracking and opening mainly occur at the 1/4 span. Compared with the rigid “Tie” connection, the mid-span deflection of the main span increases by 25.03% and the relative deflection of the section near the shear surface increases by 99.89%. However, when there are penetrating cracks and openings in the shear surface at the 1/2 span, compared with the 1/4 span position, the mid-span deflection of the main span and the relative deflection of the cross-section increase by 4.50%. The deflection of the main span increases with the failure of the shear surface.

These conclusions can guide the analysis of deflection development in long-span prestressed continuous rigid-frame bridges.

The swivel construction method is a specially designed process used to build bridges that cross rivers, valleys, railroads and other obstacles. To carry out this construction method safely, real-time monitoring of the bridge rotation process is required to ensure a smooth swivel operation without collisions. However, the traditional means of monitoring using Electronic Total Station tools cannot realize real-time monitoring, and monitoring using motion sensors or GPS is cumbersome to use.

This study proposes a monitoring method based on a series of computer vision (CV) technologies, which can monitor the rotation angle, velocity and inclination angle of the swivel construction in real-time. First, three proposed CV algorithms was developed in a laboratory environment. The experimental tests were carried out on a bridge scale model to select the outperformed algorithms for rotation, velocity and inclination monitor, respectively, as the final monitoring method in proposed method. Then, the selected method was implemented to monitor an actual bridge during its swivel construction to verify the applicability.

In the laboratory study, the monitoring data measured with the selected monitoring algorithms was compared with those measured by an Electronic Total Station and the errors in terms of rotation angle, velocity and inclination angle, were 0.040%, 0.040%, and −0.454%, respectively, thus validating the accuracy of the proposed method. In the pilot actual application, the method was shown to be feasible in a real construction application.

In a well-controlled laboratory the optimal algorithms for bridge swivel construction are identified and in an actual project the proposed method is verified. The proposed CV method is complementary to the use of Electronic Total Station tools, motion sensors, and GPS for safety monitoring of swivel construction of bridges. It also contributes to being a possible approach without data-driven model training. Its principal advantages are that it both provides real-time monitoring and is easy to deploy in real construction applications.

A bridge network is a major capital asset that requires continuing investment in order to maintain the network within acceptable limits of safety and serviceability. Ranking and prioritizing procedures have been widely used by several departments of transportation to select bridges for intervention and to distribute the available funds among competing projects. The available ranking and prioritizing procedures have various drawbacks, and an improved, rational ranking and prioritizing procedure is needed. The paper aims to address these issues.

The requirements and characteristics of an innovative ranking and prioritizing method are identified during interviews with professionals involved in bridge management. Based on these requirements, multi‐attribute utility theory (MAUT) is selected to develop the method. A technique to develop utility functions based on the analytical hierarchy process (AHP) is discussed. A hierarchy structure that captures the decision‐making elements is presented. A case study is used to demonstrate the applicability and the validity of the proposed ranking method.

The research findings have identified the decision objectives and the criteria essential to rank and prioritize bridge projects, and these are included within a framework to rank and prioritize bridge projects while incorporating experts' input in the process.

The proposed framework includes weights for the various objectives and recommends utility functions to evaluate the different attributes. In addition, the framework provides flexibility to adjust the weights and to modify the utility functions to reflect network‐specific characteristics. This method can be used by departments of transportation to rank bridges in a network, even incorporating conflicting criteria, and it can be integrated within an already implemented bridge management methodology.

Ranking and prioritizing projects are essential steps in bridge management. Current methods for ranking and prioritizing bridge projects are associated with various drawbacks. This paper proposes an innovative ranking method for bridge networks, based on MAUT. This theory provides flexibility for the decision makers in expressing their degree of satisfaction with each bridge attribute.

Infrastructure maintenance management has become a challenge field for civil engineers and government managers because of the increasing number of deteriorated structures, their complicated spatial locations, the improved service requirements, the limited maintenance budgets and so on. Therefore, maintenance management approaches have been developed for civil infrastructures such as bridges and roads over the past several decades, but most of such approaches focused on one specific structure only – project‐level maintenance management. Now, there are increasing demands and appropriate conditions for network‐level maintenance management for civil infrastructure systems. Aims to explore such a maintenance management approach by integrating and applying the current information technologies, which include the database management system, geographic information system, genetic algorithm and the Internet. Several possible applications of each technology are discussed for solving real‐world problems.

This paper aims to obtain the further and overall generation about the static characteristics of the structure for the better application of the structure.

Through nonlinear finite element simulation, serials of comparative analyses are performed on this structure and other three assumed structures, which illustrate the effect of the main part of the structure on the structural static properties. Meanwhile, adopting the first order method, spatial cable force optimization makes the structural mechanic more rational.

Under same level stress, this three‐main‐truss and three‐cable‐plane bridge could save almost 38.8 percent vertical chords materials consumption at least. In contrast, this bridge has a lower lateral torsional stiffness, considering the key to raise the lateral and torsional stiffness is enhancing axial stiffness of plane bracing, the suitable plane bracing members area is twice as the original area. After rational optimization, the cable tension ratio between the mid‐cable plane and the two side‐cable planes ranges from 1.09 to 1.14.

The work in this paper of the comparative analysis could give other engineers a way to a deep analysis method for the structural analysis, especially in civil engineering. The conclusions would provide other designers some applied advice.

Bridge lines represent a way for designers to expand their business, because typically designer merchandise is supplied to a limited number of stores. With bridge lines, the prices are lower and the line can be supplied to more stores. The bridge line market has been rapidly evolving in recent years. Retailers are paying close attention to this sector, particularly in the light of the stagnant demand for more expensive designer ready‐to‐wear collections. Despite the general economic recession, the culture of wearing fashion in the 1990s has paved the way to the growth of bridge lines.

The potential threats of extreme events to highway bridges have received increased attention from government agencies, the engineering and construction communities, and the traveling public. These events include terrorist attacks as well as human‐induced and natural hazards such as earthquakes, explosions, fires, floods, and hurricanes. To respond to the potential threats on highway bridges, a research project was conducted to identify rapid bridge replacement processes, techniques, and needs for improvements.

To achieve the research objectives, a detailed case study of previous bridge replacement following an extreme event was conducted. The case study was performed using a three‐step approach. First, the research team reviewed the literature related to the case. Second, the research team interviewed the people who were involved with the case via the telephone. Third, the research team conducted a written survey to gain knowledge about the previously unanswered questions and additional information related to the case.

After studying the case, lessons learned were identified first. Then, the research team determined the processes that were used in the rapid bridge replacements and the needed improvements so that the research community could investigate new technologies to advance current practices.

The lessons learned could be of benefit to government agencies who are responsible for development of the enhanced emergency response plans for highway bridges, and engineering and construction communities who are responsible for design and reconstruction of the damaged bridges. The development of new technologies, if successful, will ultimately enhance the capability of rapid bridge replacement after extreme events.

The purpose of this evaluative study is an attempt to understand the bridging programme by drawing on the work of Wadsworth and to prove that a place still exists for bridging programmes within the University of Johannesburg and the higher education sector in South Africa.

The research study is both quantitative and qualitative in nature. An interpretative naturalistic approach is used to understand the thinking and experiences of the students in the bridging programme.

This study reveals, first that a causal relationship exists between the length of the bridging programme and how long students take to successfully complete the national diploma in engineering. Second, that bridging programmes can contribute to the success of engineering students who want to successfully complete their engineering studies within the designated timespan. Third, that, if designated staff are utilized in the teaching of the bridging programmes, students are able to receive the necessary support which enables them to successfully complete the national diploma in engineering.

This research reveals that bridging programmes, implemented over an extended period, are valuable because they allow student access to higher education and lay a solid foundation by equipping them with the knowledge and skills necessary for success in mainstream diplomas such as the national diploma in engineering. These programmes put into practice the shift of policy emphasis from “access” to “success”, which has implications not only for the University of Johannesburg but also for the higher education sector in South Africa.