Development of An Exposure Model for Bridge Structures in Northern Algeria

In recent years, the use of large scale seismic risk assessment has become increasingly popular to evaluate the fragility of a specific region to an earthquake event, through the convolution of hazard, exposure and vulnerability. These studies tend to focus on the building stock of the region and sometimes neglect the evaluation of the infrastructure, which has great importance when determining the ability of a social group to attend to a disaster and to eventually resume normal activities. This study, developed within the scope of the EU-funded project ITERATE (Improved Tools for Disaster Risk Mitigation in Algeria), focuses on the proposal of an exposure model for bridge structures in Northern Algeria. The proposed model was developed using existing national data surveys, as well as satellite information and field observations. As a result, the location and detailed characterization of a significant share of the Algeria roadway bridge inventory was developed, as well as the definition of a taxonomy that is able to classify the most common structural systems used in Algerian bridge construction. The outcome of this study serves as input to estimate the fragility of the bridge infrastructure inventory and, furthermore, to the overall risk assessment of the Northern Algerian region. Such fragility model will, in turn, enable the evaluation of earthquake scenarios at a regional scale and provide valuable information to decision makers for the implementation of risk mitigation measures.

Cable Replacement of the Tacitus Cable Stayed Bridge

As part of a major renovation programme of critical highway infrastructure in the Netherlands, the Tacitus Bridge at Ewijk, a 1055-metre-long orthotropic steel box girder deck of ten spans, with a main cable-stayed span of 270 metres, has undergone extensive strengthening and refurbishment. Due to the presence of micro-fissure defects identified in the existing lock coiled stay cables and an increase in permanent load on the bridge deck resulting from the addition of a high strength concrete overlay acting compositely with the orthotropic steel deck, it was concluded that the existing stay cables needed replacement. This paper presents the analytical approach developed to verify that the existing stay cables could be removed with no additional temporary supports and the use of advanced non-linear techniques to predict and monitor the performance of the bridge during each step of destressing the existing stay cables and of tensioning the new parallel strand cables.

Repair of Major Cracks in Central Spans of the 4 Span Continuous Bridge, India

Varsova Bridge is across Vasai Creek, about 35 Km from Mumbai, India. It is on National Highway 48. Two bridges, 555.32m long, exist at the crossing, built in 1970 and 2004 respectively. Old bridge has central 4 spans, built in continuous PSC box girder su configuration of 57.3 + 2 x 114.6 + 57.3 construction technique. 114.6m span on Mumbai end developed a major crack, 4mm wi about 12m from mid span. Main c height in both webs. The paper describes the investigations made through analysis the probable reasons and deciding remedial measures as well as execution of the same. used four different models as per construction material parameters. Final repair measure crack locations.

Yavuz Sultan Selim (3rd Bosphorus) Bridge-Inspection and Maintenance

The Yavuz Sultan Selim bridge, also known as the 3rd Bosphorus Bridge, was opened to road traffic in August 2016. The stiffened suspension bridge, with a main span of 1408m, overall length 2250m and width 59.4m, is believed to be the first of its type. It is situated in a seismic region and exposed to a severe wind climate. It has been designed and constructed to carry 8 lanes of road traffic and twin track heavy rail-all on a single deck. <p> The bridge has been equipped with a Structural Health Monitoring (SHM) system. The instrumentation allows the monitoring of bridge behaviour. The dehumidification of the towers, bridge deck and suspension cables is also monitored. The ambient weather conditions including wind velocity, humidity and seismic activity are recorded. <p> This paper gives an overview of the inspection and maintenance regime. It also describes the observed performance of the bridge against its predicted behaviour.

Dimensioning the Flexural Strengthening of Concrete Slabs with Textile Reinforced Mortar - Litterature Data Evaluation

When strengthening reinforced concrete slabs with textile reinforced mortars (TRM), the “correct” consideration of the global bond behaviour between textile and cementitious matrix is identified as the main challenge in determining the most appropriate global analytical model. The first model evaluated here is based on classical assumptions for structural concrete design. The second model, as another extreme assumption, is completely neglecting textile bond in the cracked zone, thus assuming it as unbonded, end-anchored, external reinforcement. The third model is based on the simplifying assumption of the textile reinforcement being only significantly activated when the internal steel reinforcement is yielding. Analytical results from these approaches are compared to a database containing more than 130 test results reported in literature, and are statistically evaluated.

A North American Perspective on Service Life and Durability of Concrete Bridges

This paper describes the author’s views on durability and service life of concrete bridges in North America, considering the past, present and future. Historical materials and practices have resulted in disappointing durability and service life that does not meet modern expectations. In recent years formal service life analysis and prediction has been implemented as part of the design process for major projects, typically involving numerical modelling of time to corrosion, and mitigation or avoidance of other forms of deterioration by empirical methodology. These efforts are, however, hampered by a lack of an accepted service life design standard which is adapted to North American practice and materials. Work is under way to answer this need. In the future, further development is needed to provide a better match between expectations and reality, a more practical definition of “service life”, validation of design features implemented to mitigate or avoid deterioration for which there are no available time-based models, and improved validation of numerical modelling parameters that describe exposure conditions and material resistances.

Operation and maintenance of Impressed Current Cathodic Protection systems on concrete civil structures

Cathodic protection is a very well-known method of preventing or stopping reinforcement corrosion and thereby extending the service life of reinforced concrete civil structures. However, a number of factors, which among others are design, materials and components, installation methods, quality of workmanship, and operation and maintenance of the cathodic protection system, have influence on the functionality and effectivity of the cathodic protection system. The optimum design that fulfils the Client''s requirements to cost, traffic disruption, service life, etc. shall be determined in accordance with the structure layout and the ability of the Client''s organisation to conduct operation and maintenance. It is critical to ensure that all components are installed properly to achieve the expected service life of the system. Regular and correct operation and maintenance is also crucial to ensure the functionality and effectivity system.

Numerical Limit Analysis of Slab Bridges with Construction Joints

The conic yield criteria for reinforced concrete slabs in bending are often used when evaluating the load‐carrying capacity of slab bridges. In the last decades, the yield criteria combined with numerical limit analysis have shown to be efficient methods to determine the load carrying capacity of slabs. However, the yield criteria overestimate the torsion capacity of slabs with high reinforcement ratios and it cannot handle slabs with construction joints. In this paper, numerical limit analysis with the conic yield criteria are compared with yield criteria based on an optimized layer model. The analysis show an increasing overestimation of the load carrying capacity for increasing reinforcement degrees. Furthermore, yield criteria, which combine the conic yield criteria with an extra linear criterion due to friction, are presented for slab bridges with construction joints. The yield criteria for slabs with construction joints are used, in combination with limit analysis, to evaluate a bridge constructed of pre‐cast overturned T‐beams and in‐situ concrete. The analysis show that the load carrying capacity is overestimated, when the construction joints are not considered in the yield criteria.

mparison of model-based identification methods for reserve-capacity assessment of existing bridges

The goal of model-based structural identification is to find suitable values of parameters that affect structure behaviour. To this end, measurements are often compared with predictions of finiteelement models. Although residual minimization (RM) is a prominent methodology for structural identification, it provides wrong parameter identification when flawed model classes are adopted. Error-domain model falsification (EDMF) is an alternative methodology that helps identify candidate models – models that are compatible with behaviour measurements – among an initial model population. This study focuses on the comparison between RM and EDMF for the structural identification of a steel bridge in Exeter (UK). Advantages and limitations of both methodologies are discussed with reference to parameter identification and prognosis tasks such as quantification of reserve capacity. Results show that the employment of RM may lead to wrong identification and unsafe estimations of reserve capacity.

Great Belt Bridge – Structural monitoring

<p>The monitoring system on the Great Belt Bridge has been under a renewal process for the last 4 years. <p>Worn down sensors for alarm and maintenance purposes have been replaced by new more appropriate sensors. <p>A new structural health monitoring system for maintenance with a database and a graphical user interface (GUI) has been developed. The software collects and stores measurement data from a large number of sensors on both the cable‐suspended East Bridge and the low‐level West Bridge. From summer 2018 more than 400 sensors can be monitored from one GUI. More sensors are following in 2019. <p>The project has been carried out by Rambøll as client consultant and Krabbenhøft & Ingolfsson as main contractor.