Sliding materials – the often essential but generally weakest links in bridge bearings and expansion joints

2019 ◽  
Author(s):  
Gianni Moor ◽  
Simon Hoffmann ◽  
Danilo Della Ca'
Keyword(s):  
State Of The Art ◽  
Cycle Performance ◽  
Special Focus ◽  
Expansion Joints ◽  
Sliding Interfaces ◽  
Materials Used ◽  
Long Term Performance ◽  
Term Performance ◽  
Bridge Bearings

<p>Bridge bearings and expansion joints, being engineered components that accommodate movements and rotations, are typically the parts of a bridge that are subjected to the greatest demands although being far less robust than the main structure. As a result, they generally cannot offer a service life that approaches that of the bridge as a whole. Therefore, the durability of the bearings and expansion joints selected for use in a structure is an important factor to consider in maximizing life-cycle performance. Most bearings and expansion joints that facilitate significant superstructure movements have sliding interfaces, which provide much of the flexibility required by the main structure’s design. These sliding interfaces generally involve the use of non- ferrous materials such as PTFE, which are subjected to friction and abrasion with every movement, and are therefore the component parts that are subjected to the highest demands. Therefore, the performance of the sliding materials used in a bridge’s bearings and expansion joints has considerable influence on the structure’s long-term performance. This paper discusses this subject, with a special focus on the state-of-the-art UHMWPE alternative to the PTFE sliding material traditionally used in main sliding interfaces.</p>

Prediction of Bearing Lifetime Demands by Considering the Bridge Design and Location Parameters

2019 ◽  
Author(s):  
Minesh K. Patel ◽  
Georgios P. Balomenos
Keyword(s):  
Bridge Design ◽  
Traffic Loading ◽  
Location Parameters ◽  
Long Term Performance ◽  
Term Performance ◽  
Long Term Behavior ◽  
Bridge Bearings ◽  
Bearing Behavior ◽  
Over Time

<p>The <span>long-term performance and safety of bridges is of paramount importance. Researchers have placed significant focus on the degradation and deterioration of bridge materials such as steel and concrete, but significantly less is known about the long-term behavior of bridge bearings. Uncertainty in the bearing behavior over time leads to challenges about when the bearings should be inspected and potentially replaced. However, bearing demands vary greatly based on the design of the bridge (e.g. differences in bridge material, girder type, span, height, and location). This paper finds trends in lifetime bearing demands from seismic, thermal, and traffic loading when the bridge design and location parameters are considered. These results can be used to identify which of the parameters have the greatest influence on the lifetime bearing demands which can then be used, in turn, to evaluate bearing long-term performance.</span></p>

The investigation and proposed rehabilitation of the Tsing Yi South Bridge, Hong Kong

1988 ◽  
Vol 15 (2) ◽  
pp. 190-198
Author(s):  
A. S. Beard ◽  
H. S. S. Tung
Keyword(s):  
Prestressed Concrete ◽  
Load Testing ◽  
Concrete Core ◽  
Box Girder ◽  
Expansion Joints ◽  
Radiographic Inspection ◽  
Core Extraction ◽  
Long Term Performance ◽  
Term Performance

The Tsing Yi South Bridge was constructed in the early 1970s to provide access between Tsing Yi Island and the mainland at Kwai Chung. It has a prestressed concrete box girder superstructure consisting of five independent units which are monolithic with their piers and have expansion joints at the mid-span shear hinges and the abutments. During routine maintenance it was found that the superstructure cantilevers were deflecting excessively, and consequently a thorough inspection and appraisal were commissioned. These included a complete visual inspection, concrete core extraction, radiographic inspection of prestressing tendons and a programme of load testing. The bridge was also reanalyzed to check its long-term performance. Subsequently, a rehabilitation scheme was designed to recover part of the deflection. This involved the introduction of additional prestress near the box girder's top flange. Key words: prestressed concrete, structural assessment, creep, shrinkage, radiographic inspection, rehabilitation, external prestressing.

Durability of vapor-permeable waterproof textile materials used in sailing protective apparel

2017 ◽  
Vol 88 (24) ◽  
pp. 2825-2840 ◽  
Author(s):  
Olga Troynikov ◽  
Nazia Nawaz ◽  
Chris Watson
Keyword(s):  
Protective Clothing ◽  
Mechanical Treatment ◽  
Thermal Protection ◽  
Unit Area ◽  
Textile Materials ◽  
Failure Pressure ◽  
Materials Used ◽  
Long Term Performance ◽  
Term Performance

Vapor-permeable waterproof textiles (VPWTs) are used in sailing apparel to protect wearers from weather and water exposure. They must also withstand knocks and abrasion. Failure of fabric waterproofing results in water intrusion, reduced thermal protection and potentially hypothermia. There are no standard methods for testing the waterproof durability of fabrics in these conditions. To evaluate waterproofing durability, we simulated high levels of wear on leading commercially available VPWT assemblies through mechanical treatment in wet conditions. To compare fabrics on multiple performance characteristics, we developed a Total Durability Penalty index associated with leaks and ruptures, weighted by failure pressure. The experiment revealed significant differences in VPWT deterioration under mechanical treatment. We determined that the mass per unit area and thickness of VPWT fabrics are positively correlated with pressure at leakage; that rupture is significantly and negatively associated with the mass per unit area and thickness of the inner and outer layers of fabric; and leakage pressure is positively correlated with the same parameters. These results show that it is important to consider wear conditions when assessing the long-term performance attributes of protective clothing assemblies.

Long-Term Performance of Bridge Elements Using Integrated Deterioration Method Incorporating Elman Neural Network

2012 ◽  
Vol 204-208 ◽  
pp. 1980-1987 ◽  
Author(s):  
Guo Ping Bu ◽  
Jae Ho Lee ◽  
Hong Guan ◽  
Yew Chaye Loo ◽  
Michael Blumenstein
Keyword(s):  
State Of The Art ◽  
Bridge Management ◽  
Elman Neural Network ◽  
Integrated Method ◽  
Modeling Techniques ◽  
Bridge Performance ◽  
Improved Performance ◽  
Long Term Performance ◽  
Term Performance

Currently, probabilistic deterioration modeling techniques have been employed in most state-of-the-art Bridge Management Systems (BMSs) to predict future bridge condition ratings. As confirmed by many researchers, the reliability of the probabilistic deterioration models rely heavily on the sufficient amount of condition data together with their well-distributed historical deterioration patterns over time. However, inspection records are usually insufficient in most bridge agencies. As a result, a typical standalone probabilistic model (e.g. state-based or time-based model) is not promising for forecasting a reliable bridge long-term performance. To minimise the shortcomings of lacking condition data, an integrated method using a combination of state- and time-based techniques has recently been developed and has demonstrated an improved performance as compared to the standalone techniques. However, certain shortcomings still remain in the integrated method which necessities further improvement. In this study, the core component of the state-based modeling is replaced by an Elman Neural Networks (ENN). The integrated method incorporated with ENN is more effective in predicting long-term bridge performance as compared to the typical deterioration modeling techniques. As part of comprehensive case studies, this paper presents the deterioration prediction of 52 bridge elements with material types of Steel (S), Timber (T) and Other (O). These elements are selected from 94 bridges (totaling 4,115 inspection records). The enhanced reliability of the proposed integrated method incorporating ENN is confirmed.

Fine Particle Mass Monitoring with Low-Cost Sensors: Corrections and Long-Term Performance Evaluation

2019 ◽  
Author(s):  
Carl Malings ◽  
Rebecca Tanzer ◽  
Aliaksei Hauryliuk ◽  
Provat K. Saha ◽  
Allen L. Robinson ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Fine Particle ◽  
Low Cost ◽  
Particle Mass ◽  
Long Term Performance ◽  
Term Performance

Long-term performance of the Hancock bioprosthetic conduit for aortic root replacement

2008 ◽  
Vol 56 (S 1) ◽  
Author(s):  
CC Badiu ◽  
W Eichinger ◽  
D Ruzicka ◽  
I Hettich ◽  
S Bleiziffer ◽  
...  
Keyword(s):  
Aortic Root ◽  
Aortic Root Replacement ◽  
Long Term Performance ◽  
Term Performance
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