scholarly journals Crack propagation and residual load‐bearing behavior of composite dowels – effects on the global behavior of composite girders under cyclic loading

ce/papers ◽  
2021 ◽  
Vol 4 (2-4) ◽  
pp. 657-665
Author(s):  
Kevin Wolters ◽  
Georgios Christou ◽  
Markus Feldmann
Keyword(s):  
Cyclic Loading ◽  
Crack Propagation ◽  
Global Behavior ◽  
Load Bearing ◽  
Bearing Behavior ◽  
Composite Girders

Crack initiation and crack propagation under thermal cyclic loading

1990 ◽  
Vol 8 (2) ◽  
pp. 98-104 ◽  
Author(s):  
K. Bethge ◽  
D. Munz ◽  
J. Neumann
Keyword(s):  
Cyclic Loading ◽  
Crack Initiation ◽  
Crack Propagation

scholarly journals Bond Fatigue of TRC with Epoxy Impregnated Carbon Textiles

2019 ◽  
Vol 9 (10) ◽  
pp. 1980 ◽  
Author(s):  
Juliane Wagner ◽  
Manfred Curbach
Keyword(s):  
Cyclic Loading ◽  
Residual Strength ◽  
Negative Impact ◽  
Fatigue Behavior ◽  
Tensile Load ◽  
Textile Reinforced Concrete ◽  
Anchorage Length ◽  
Static Tests ◽  
Number Of Cycles ◽  
Bearing Behavior

For the economical construction of fatigue loaded structures with textile reinforced concrete (TRC), it is necessary to investigate the fatigue behavior of the materials. Since next to the tensile load-bearing behavior, the bond behavior of a material is crucial as well, the present paper deals with the bond fatigue of TRC with epoxy-impregnated carbon textiles. First, static tests are carried out to determine the sufficient anchorage length of the investigated material combination. Afterwards, the influence of cyclic loading on the necessary anchorage length, deformation, stiffness, and residual strength is investigated. The results of the cyclic tests are summarized in stress-number of cycles to failure (S-N) diagrams. In the end, it can be said that the cyclic loading has no negative impact on the necessary anchorage length. If specimens withstand the cyclic loading, there is no difference between their residual strength and the reference strength. The failure of specimens occurs only at high load levels, provided that the anchorage length is sufficient.

scholarly journals Fatigue and crack propagation investigations on composite dowels using an inclined single push-out test

2018 ◽  
Author(s):  
Kevin Wolters ◽  
Markus Feldmann
Keyword(s):  
Crack Propagation ◽  
Bearing Capacity ◽  
Fatigue Behaviour ◽  
Steel Part ◽  
Stress Distributions ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Composite Joint ◽  
Residual Capacity ◽  
Push Out

The current fatigue design of composite dowels is based on the structure stress concept for the steel part and upper load limitations to avoid concrete fatigue and a degradation of the composite joint. Therefore the aim of the existing concept is to avoid any fatigue of the composite structure. A fatigue concept considering residual load bearing capacity of torn steel connectors and the transfer of forces to less stressed composite dowels in the beam has great economic potential and leads to a better safety assessment. Therefore, further investigations of fatigue behaviour and crack propagation of composite dowels are necessary. In a first step a single composite dowel is investigated in small-part tests. By the use of finite element models a new inclined single push-out test stand has been developed in order to reproduce the force and stress distributions within a composite beam as precisely as possible with the small-part tests. This ensures the comparability of the crack initiation location and crack propagation. In the test series the influences of different stress ranges and cycle numbers on crack propagation of the steel dowel are investigated. Furthermore the residual load-bearing capacity is determined and compared to static load-bearing behaviour of uncracked steel parts of composite dowels. This paper concentrates on the numerical evaluation of crack propagation and residual capacity.

Crack Propagation Prediction Using Haensel Damage Model

2012 ◽  
Author(s):  
Piotr Bednarz ◽  
Jaroslaw Szwedowicz
Keyword(s):  
Cyclic Loading ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Damage Model ◽  
Lifetime Prediction ◽  
Dissipated Energy ◽  
Mathematical Approach ◽  
Loading Conditions ◽  
Stored Energy ◽  
Tensile Stresses

The Haensel damage model correlates lifetime of a component until crack initiation to the dissipated and stored energy in the material during cyclic loading. The crack initiation is influenced by mean stresses. The Haensel damage model considers the mean stress effect by including compressive and tensile stresses in calculations of elastic strain energy during cyclic loading conditions. The goal of the paper is to extend the above model to predict crack propagation under large cyclic plasticity and non-proportional loading conditions. After voids initiation onset of necking, voids growth and linking takes place among them. During this process a mesocrack is created. This stage of fracture involves the same amount of released energy for new crack surface creation as dissipated energy for mesocrack initiation. The amount of dissipated and stored energy is related to the process zone size and to the number of cycles. Ilyushin’s postulate is used to calculate the amount of dissipated energy. In order to consider a contribution of tensile stresses only during loading to crack propagation, tensile/compressive split is performed for the stress tensor. One of the key drivers of this paper is to provide a straightforward engineering approach, which does not require explicit modelling of cracks. The proposed mathematical approach accounts for redistribution of stresses, strains and energy during crack propagation. This allows to approximate the observed effect of distribution of dissipated energy on the front of a crack tip. The developed approach is validated through FE (Finite Element) simulations of the Dowling and Begley experiment. The Haensel lifetime prediction of Dowling’s experiment is in good agreement with the experimental data and the explicit FE results. Finally, the proposed mathematical approach simplifies significantly the engineering effort for Nonlinear Fracture Mechanics lifetime prediction by avoiding the requirement to simulate real crack propagation using node base release methods, XFEM or remeshing procedures.

scholarly journals Influence of the surface modification by sanding of carbon textile reinforcements on the bond and load-bearing behavior of textile reinforced concrete

2019 ◽  
Vol 289 ◽  
pp. 04006
Author(s):  
Cynthia Morales Cruz ◽  
Michael Raupach
Keyword(s):  
Surface Modification ◽  
Reinforced Concrete ◽  
Tensile Tests ◽  
Measuring System ◽  
Uniaxial Tensile ◽  
Testing Time ◽  
Textile Reinforced Concrete ◽  
Load Bearing ◽  
Surface Modified ◽  
Bearing Behavior

In the context of the application of carbon Textile Reinforced Concrete (TRC) layers for the durable repair of building surfaces, uniaxial tensile tests on rectangular TRC samples were carried out to compare the bond and load-bearing behavior of an epoxy-impregnated carbon textile and its surface modified version. The aim of the surface modification, consisting of a subsequent coating with epoxy resin and sanding with quartz sand, is the improvement of the composite material regarding crack width reduction and an increase of the load-bearing capacity. A total of 15 series were examined and the parameters: reinforcement type, orientation and ratio were varied. In addition, long-term load tests were conducted. An optical 3D-video measuring system in combination with a DIC-software was used, which allowed the analysis of the process of crack formation during the entire testing time. With the surface modified reinforcement the formation of approx. 1.5 times the number of cracks with averagely 33 % smaller crack widths and up to 50 % smaller crack spacings were observed, regardless of the ratio of reinforcement. The residual behaviour of the series subjected to a permanent load of 1500 MPa over 1000 h showed no reduction of the tensile stress compared to short-term tests.

Experimental and numerical investigation on the vertical bearing behavior of discrete connected new-type precast reinforced concrete floor system

2020 ◽  
Vol 23 (11) ◽  
pp. 2276-2291
Author(s):  
Rui Pang ◽  
Yibo Zhang ◽  
Longji Dang ◽  
Lanbo Zhang ◽  
Shuting Liang
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cover Plate ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Concrete Floor ◽  
New Type ◽  
Vertical Bearing ◽  
Floor System ◽  
Bearing Behavior

This article proposes a new type of discrete connected precast reinforced concrete diaphragm floor system that consists of precast flat slabs and slab joint connectors. An experimental investigation of discrete connected new-type precast reinforced concrete diaphragm under a vertical distributed static load was conducted, and the effect of slab joint connectors on the load-bearing capacity was evaluated. Then, a finite element analysis of discrete connected new-type precast reinforced concrete diaphragm, precast reinforced concrete floors without slab connectors, and cast-in-situ reinforced concrete floor were performed to understand their working mechanism and determine the differences in load-bearing behavior. The results indicate that the load-bearing capacity and stiffness of discrete connected new-type precast reinforced concrete diaphragm increase considerably as the hairpin and cover plate hybrid slab joint connectors can efficiently connect adjacent precast slabs and enable them to work together under a vertical load by transmitting the shear and moment forces in the orthogonal slab laying direction. The deflection of discrete connected new-type precast reinforced concrete diaphragm in orthogonal slab laying direction is mainly caused by the opening deformation of the slab joint and the rotational deformation of the precast slabs. This flexural deformation feature can provide reference for establishing the bending stiffness analytical model of discrete connected new-type precast reinforced concrete diaphragm in orthogonal slab laying direction, which is vitally important for foundation of the vertical bearing capacity and deformation calculation method. The deflection and crack distribution patterns infer that the discrete connected new-type precast reinforced concrete diaphragm processes the deformation characteristic of two-way slab floor, which can provide a basis for the theoretical analysis of discrete connected new-type precast reinforced concrete diaphragm.

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