Papers by Keyword: Bridge Maintenance

Abstract: This study deals with the paramount topic of sustainable and durable composite materials for repair of damaged existing bridge. Reinforced concrete is the most used composite system in structural design but, across several decades, it has shown some fragilities related to chemico-physical resistance. Durability improvement by means of innovative repair systems represent, therefore, a crucial economic parameter allowing a highly significant reduction of maintenance cost. A maintenance scenario is here simulated, considering a repair composite realized with a binary geopolymer binder, obtained by activating two industrial by-products, namely coal fly ash and blast furnace slag, in alkaline environment. Physico-mechanical characterization of geopolymer concrete is also performed, showing the suitability of this innovative repair system. In order to investigate the effectiveness of geopolymer, a 3D finite element model is developed in Sap2000 to represent the complex behavior of a full-scale Italian highway bridge. Numerical simulations are conducted by modeling the geopolymer concrete as a jacketing applied to the damaged piers. Results reveal that the designed repair system could increase shear capacity of bridge piers under seismic conditions, not neglecting the low cost of raw materials and the high durability of geopolymers.

Abstract: Fiber-reinforced concrete is well known for crack control by bridging cracks in the concrete. Short, discontinuous fibers are added into plain concrete to provide post-cracking ductility to the fiber-reinforced concrete. Although fiber-reinforced concrete has been used in various civil engineering applications, the practical application of fiber-reinforced concrete in bridge approach slabs is rarely found. In this paper, steel fibers, serving as macro-fibers, and polyvinyl alcohol fibers, serving as micro-fibers, were added to the approach slab concrete for crack control purpose. This paper describes flexural tests of four fiber-reinforced concrete beams and loading test of a full scale fiber-reinforced concrete approach slab. Results from the flexural beam test show that the addition of fibers greatly improves the fracture toughness of the concrete. Results from the loading test show that the overall performance of the slab is comparable to conventional reinforced concrete approach slabs, and the surface cracks on the slab due to negative moment can be adequately controlled by the addition of steel and polyvinyl alcohol fibers into concrete, even without top reinforcement mat.

Abstract: It is important to prioritize maintenance needs to bridges that are most significant to the functionality of the entire network under budget constraints. In this paper, the network-level bridge maintenance planning problem is solved by time series-based multi-attribute decision-making method. First, the decision-making matrix composed of index value is introduced and then growth matrix of each time sample points is derived from decision-making matrix. Second, the composite indicator values and integrated growth index values of each bridge can be calculated through the information entropy. Third, the sort of bridge combination of value is counted by composing the composite indicator values and integrated growth index values of each bridge. According to the sort of bridge combination of value, it is easy to obtain a bridge maintenance order. Finally, as an illustration example, time series-based multi-attribute decision-making method is applied to an existing 10-bridge network and proved the effectiveness and feasibility of the proposed method.

Abstract: As number of aged bridges increases, determining how to generate bridge maintenance strategy gradually becomes a research hotspot. Markov process was used to analyze bridge maintenance cost according to its characteristics during serving period. A kind of maintenance decision-making method was put forward based on OWA and OWGA from the angle of sustainable development. And this method was proved applicable by an example.

Abstract: The existing concrete bridges are often required to carry an increasing volume of traffic, higher speed and heavier trucks, so the bridge owners pay more attention to the actual fatigue damage and service safety of such structures. In this paper, Acoustic Emission (AE) sensors are used to monitor and evaluate the fatigue and damage of Yaoxian Bridge, which is the first field AE monitoring using Physical Acoustics Company equipment and sensors in China existing concrete bridge. This AE sensor has fine frequency bandwidth of interest to bridge monitoring, which is applicable to local cracking and damage positions and can monitor fatigue cracks and damage in close-range. In the field inspection, healthy monitoring was conducted at several locations, including the box concrete girder webs, bottom plates and deck plates using AE sensors. Based on AE monitoring data, the fatigue and damage conditions of box concrete girders was analyzed in order to propose theoretical basis and the rational advices for Yaoxian Bridge maintenance.

Abstract: Bridge is the hub of a road, playing an important role in transportation. With the age of bridges increasing in recent years, the condition of bridges is deteriorating. Bridge deterioration usually results from multiple factors. Studies in exploring the factors leading to bridge deterioration and its state estimation are booming. However, studies in the relationship between bridge deterioration and external environment by using database are still limited. Since 1992, National Bridge Inventory (NBI) has collected basic and historical information of bridges in every state, a very rich database which should include some valuable knowledge. Hence, through clustering and classifying in data mining, this study explores association rules for bridge deterioration, which is displayed in decision tree with clear routes for reference. Using association rules developed by thus study, bridge maintenance personnel can understand the future state of the bridge under their jurisdiction, respond to risks and costs of bridge deterioration, extend the service life of bridges, and protect the safety of road users.

Abstract: Approach slabs are commonly used to provide a smooth transition between the roadway and the highway bridge. Conventional construction of approach slabs uses cast-in-place reinforced concrete slabs that are anchored to the abutment. Maintenance of bridges, however, often requires repair or replacement of approach slabs due to damage from traffic, washout of fill materials, and settlement of the approach embankment etc. This paper describes recent tests of full-size approach slabs with conventional steel reinforcement as well as pultruded fiber-reinforced polymer grating and glass fiber- reinforced polymer rebars.

Abstract: In this paper a method for safety and condition assessment of bridge components based on long-term monitoring data and reliability analysis is proposed with the target to provide quantitative information to bridge managers for decision making on optimizing and prioritizing bridge inspection and maintenance. In the proposed method, the probability density function (PDF) of the load effect is obtained directly from continuous strain measurement, while the PDF of the resistance is determined using the material strength and its variation coefficient prescribed in provisions or obtained by material tests, and further revised with the damage identification results. Then the safety indices of structural components are estimated using the first-order reliability method (FORM), which can be readily used to decide bridge inspection/maintenance strategy because the correspondence between the safety index and the required maintenance action has been established. This method can incorporate the identified structural damage in a probabilistic manner into the safety index evaluation. Case studies of two truss bridge structures have been provided to illustrate the proposed method.