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Zur Tragfähigkeit von Stahlbeton-Fahrbahnplatten ohne Querkraftbewehrung
Citation Link: https://doi.org/10.15480/882.1052
Other Titles
Shear capacity of concrete bridge decks without transverse reinforcement
Publikationstyp
Doctoral Thesis
Publikationsdatum
2010
Sprache
German
Author
Advisor
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2010-09-27
Institut
After the introduction of the new generation of standards, which are based on the concept of partial safety factors, it became apparent, that the design of reinforced concrete bridge deck slabs is now often governed by the shear bearing capacity. While a sufficient bearing capacity of thin slabs is frequently only reached with the alignment of shear reinforcements, it has formerly been common practice to construct thin bridge deck slabs without shear reinforcement. It is highly essential to further examine this evident discrepancy in order to achieve sound design regulations and correctly asses the reliability of existing bridge deck slabs. Hence, the purpose of this thesis is to analyse the bearing behaviour of slabs under concentrated loads, such as wheel loads, and to further improve the evaluation of the shear bearing capacity of reinforced concrete bridge deck slabs without shear reinforcement. The influencing factors, that have to be integrated in an ap-propriate design formula, are systematically investigated. Furthermore, the load bearing behav-iour of reinforced concrete slabs without shear reinforcement under concentrated loads is studied experimentally and numerically. Fundamental models for the numerical analysis of the shear bearing capacity of reinforced concrete slabs are discussed and compared with test results.
The first part of the thesis focuses on the bearing behaviour of reinforced concrete members under shear based on studies of published research results. A substantial database comprising test data and results of experiments with reinforced concrete beams exhibiting shear failures and various models to calculate the shear bearing capacity are discussed. A new model based on the theory of the critical crack in combination with fracture machanics is proposed. The design for-mula is developed by a regression analysis of the shear database. The model is verified and com-pared to the shear database and other models. Particular emphasis is devoted to the accuracy of the various models predicting the bearing capacity of tests with characteristics typical for bridge deck slabs. The model, which has been developed in this thesis, shows a better agreement with test results than the design formula of the present DIN 1045-1. Furthermore, the influence of typical bridge deck slab geometries and load arrangements is examined. A beneficial effect of a tapered slab bottom on the shear capacity as implemented in the DIN code with the reduction shear force Vcc cannot be verified by test results.
The second part of the thesis starts with an overview of methods for calculating the shear force distribution in slabs. Following this, large scale tests with slabs under point loads, repre-senting bridge deck slabs, are described and analysed. A procedure for calculating the bearing capacity of bridge deck slabs without shear reinforcement accounting for possible deviations of principal moment, principal shear force and reinforcement directions is described and compared with test results. It appears that the implementation of the known design formulas provides con-servative estimates of the shear bearing capacity. While the capacities calculated with various design formulas differ little, the choice of method determining the design shear force distribution results in a considerable variation of the calculated bearing capacity. The need for further ex-perimental research of slabs under pointloads with and without haunches is emphasized.
The first part of the thesis focuses on the bearing behaviour of reinforced concrete members under shear based on studies of published research results. A substantial database comprising test data and results of experiments with reinforced concrete beams exhibiting shear failures and various models to calculate the shear bearing capacity are discussed. A new model based on the theory of the critical crack in combination with fracture machanics is proposed. The design for-mula is developed by a regression analysis of the shear database. The model is verified and com-pared to the shear database and other models. Particular emphasis is devoted to the accuracy of the various models predicting the bearing capacity of tests with characteristics typical for bridge deck slabs. The model, which has been developed in this thesis, shows a better agreement with test results than the design formula of the present DIN 1045-1. Furthermore, the influence of typical bridge deck slab geometries and load arrangements is examined. A beneficial effect of a tapered slab bottom on the shear capacity as implemented in the DIN code with the reduction shear force Vcc cannot be verified by test results.
The second part of the thesis starts with an overview of methods for calculating the shear force distribution in slabs. Following this, large scale tests with slabs under point loads, repre-senting bridge deck slabs, are described and analysed. A procedure for calculating the bearing capacity of bridge deck slabs without shear reinforcement accounting for possible deviations of principal moment, principal shear force and reinforcement directions is described and compared with test results. It appears that the implementation of the known design formulas provides con-servative estimates of the shear bearing capacity. While the capacities calculated with various design formulas differ little, the choice of method determining the design shear force distribution results in a considerable variation of the calculated bearing capacity. The need for further ex-perimental research of slabs under pointloads with and without haunches is emphasized.
Schlagworte
Querkraftbemessung
Stahlbeton
Fahrbahnplatten
ohne Querkraftbewehrung
Shear design
concrete bridge decks
without transverse reinforcement
DDC Class
720: Architektur
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