Full‐scale shear tests on post‐tensioned bridge girders of existing bridges

Self Cite

In recent years, the assessment of the shear resistance of existing post‐tensioned multispan bridges has become a frequent task for civil engineers. New models developed for this purpose need to be verified, since the number of shear‐related results of tests executed under real loading conditions at the interior support of multispan systems is very limited. In this study, eight shear tests carried out on four specimens are presented. The effects of different prestressing grades, cross‐sections, and amounts of transverse reinforcement are investigated. Two test setups were used in order to reproduce the internal forces occurring at the interior and end supports, respectively, of actual multispan bridges. With the aid of close‐range photogrammetry, detailed measurements of the kinematics of the critical flexural‐shear cracks were performed. In this study, it is demonstrated that arching action plays a major role for the shear capacity of slender post‐tensioned beams. The predictions of the shear capacity determined with various shear design models show that these models are conservative, especially with respect to the shear capacity for the region around the interior supports. However, the evaluation of the models also shows that the flexural‐shear crack model yields very promising results of the shear capacity of post‐tensioned beams with low shear reinforcement ratios.

Section: Flexural-shear Crack Modelmentioning

confidence: 99%

Section: Prediction Of the Shear Strength With Different Analytical Amentioning

confidence: 99%

Section: Prediction Of the Shear Strength With Different Analytical Amentioning

confidence: 99%

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Experimental and theoretical study on the shear behavior of single‐ and multi‐span T‐ and I‐shaped post‐tensioned beams

Huber¹,

Huber

Kollegger

2019

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“…An important aspect in the assessment procedure is the verification of the shear strength, as also pointed out by Huber et al 1 , mainly due to the revision of shear codes over the years. If assessment is based on the current Eurocodes, this often leads to shear criteria that do not suffice and (expensive) strengthening of the structures would be required.…”

Section: Introductionmentioning

confidence: 99%

Assessment of posttensioned concrete beams from the 1940s: Large‐scale load testing, numerical analysis and Bayesian assessment of prestressing losses

Botte

Vereecken

Taerwe

et al. 2021

The UCO textile factory was built in Ghent (Belgium) in the period 1947–1948. The roof structure covered an area of about 35,000 m2 and consisted of 100 primary beams and 600 secondary beams. These post‐tensioned beams were designed by prof. Gustave Magnel, who was a world‐leading expert in the field of prestressed concrete. This project was one of the first important large‐scale applications of prestressed concrete in industrial buildings in the world and also the first large scale application of on site prefabrication. Recently, part of the factory building was demolished and a primary beam and secondary beam of the roof structure were transferred to the Magnel‐Vandepitte Laboratory for Building Materials and Structures for testing at an age of approximately 70 years. The primary beams have a span of 20.5 m and a maximum depth of 1.7 m. The secondary beams have a span of 13.7 m and a depth of 1 m. Only prestressing tendons (Blaton–Magnel system with Ø 5 mm wires) were present in the beams but no passive reinforcement nor stirrups are present except for the reinforcement in the corbels and the end blocks. This article describes the results of the loading tests up to failure on the beams. The experimental results are compared with results from analytical calculations. Furthermore, a nonlinear finite element model was developed and validated. Subsequently, this numerical model was used for a Bayesian‐based assessment of the prestressing losses in these beams. As such, the article presents novel information related to time‐dependent prestress losses after 70 years in service as well as the structural performance of such existing post‐tensioned concrete structures dating from that pioneering period.

“…To efficiently manage the lifecycle of such bridges, it is necessary to assess probably their present structural condition, an approximate life expectancy and potential rehabilitation or replacement of the precast structure. In practice, some methods of evaluation of aged bridges have been introduced in the last decades 7–12 . The need to assess the residual prestressing level increased due to the higher number of first prestressed concrete structures being demolished.…”

Section: Introductionmentioning

confidence: 99%

Failure and damage of a first‐generation precast prestressed bridge in Slovakia

Moravčík

Bujňáková

Bahleda

2020

In the early 1950s, the first‐generation of precast prestressed bridges was built in Europe. The prestressing technology was still relatively new and bridges were sometimes executed questionably. The consequences of poor detailing and inadequate maintenance are shown as a practical example of a 59‐years old road precast bridge in Slovakia that recently reached a near collapse state. The behavior of the damaged prestressed precast structure was verified by the full‐scale load test. In the case of advanced corrosion of the tendons, it is often very difficult to accurately determine the actual resistance of a structure. The test results published in the paper may help to find a practical method for the assessment of similar aged existing prestressed bridges.