scholarly journals Determination of parameters of a viscous-cohesive fracture model by inverse analysis

2015 ◽  
Vol 8 (5) ◽  
pp. 669-706 ◽  
Author(s):  
F. L. Gea dos Santos ◽  
J. L. A. O. Sousa
Keyword(s):  
Inverse Analysis ◽  
Fracture Process ◽  
Loading Rate ◽  
Process Zone ◽  
High Strength ◽  
Model Parameters ◽  
Cohesive Fracture ◽  
Cohesive Model ◽  
Determination Of Parameters

ABSTRACTThe quasi-brittle, loading rate dependent behaviour of the concrete, characterized by a fracture process zone (FPZ) ahead of the crack front, can be described through a viscous-cohesive model. In this paper, a viscous cohesive model proposed in a former paper is evaluated for a group of high strength concrete beams loaded at rates from 10-5 mm/s to 10+1 mm/s. A software has been developed to enable the automatic determination of the viscous-cohesive model parameters through inverse analysis on load-versus loading-point displacement (P-d) from threepoint bend tests on notched prismatic specimens. The strategy allowed the sensitivity analysis of the parameters related to viscous behaviour. The analysis of results shows that the formerly proposed model can be improved for a better simulation of the loading rate dependence on the cohesive fracture process.

scholarly journals Size of the Fracture Process Zone in High-Strength Concrete at a Wide Range of Loading Rates

2010 ◽  
Vol 24-25 ◽  
pp. 155-160 ◽  
Author(s):  
R.C. Yu ◽  
X.X. Zhang ◽  
Gonzalo Ruiz ◽  
M. Tarifa ◽  
M. Cámara
Keyword(s):  
High Strength Concrete ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Loading Rate ◽  
Process Zone ◽  
High Strength ◽  
Experimental Program ◽  
Strength Concrete ◽  
Loading Rates ◽  
Wide Range

Compared with the extensive research on properties of the fracture process zone (FPZ) under quasi-static loading conditions, much less information is available on its dynamic characterization, especially for high-strength concrete (HSC). This paper presents the very recent results of an experimental program aimed at disclosing the loading rate effect on the size and velocity of the (FPZ) in HSC. Eighteen three-point bending specimens were conducted under a wide range of loading rates from from 10-4 mm/s to 103 mm/s using either a servo-hydraulic machine or a self-designed drop-weight impact device. Four strain gauges mounted along the ligament of the specimen were used to measure the FPZ size. Surprisingly, the FPZ size remains almost constant (around 20 mm) when the loading rate varies seven orders of magnitude.

Study on Interfacial Crack Propagation and Fracture between Embedded Steel and HSHPC

2007 ◽  
Vol 348-349 ◽  
pp. 853-856
Author(s):  
Shan Suo Zheng ◽  
Lei Li ◽  
Guo Zhuan Deng ◽  
Liang Zhang
Keyword(s):  
Crack Propagation ◽  
High Performance ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
High Performance Concrete ◽  
Process Zone ◽  
Interfacial Crack ◽  
High Strength ◽  
Interfacial Fracture ◽  
Softening Process

Steel reinforced high strength and high performance concrete (SRHSHPC) specimens were experimented to study the mechanical behaviors between steel and concrete interface. In experiment, interfacial bond softening process was observed, which can be explained in terms of damage along the interface, leading to progressive reduction of shear transfer capability between steel and high strength and high performance concrete (HSHPC). In this paper, bond softening process along the interface is considered in the analysis of crack-induced debonding. Interfacial bond-slip mechanism between steel and HSHPC is studied in detail based on fracture mechanics. With the help of acoustic emissions technology, the crack propagation in the interlayer was observed, thus the interfacial crack propagation and fracture model is set up. Under the assumption that the interlayer is weak concrete compared with concrete matrix, the stress field as well as displacement field around the crack tip is deduced. The characteristics of interfacial fracture process are discussed and a model for interfacial fracture process zone is built up. With this model, the size of fracture process zone can be derived. At last, the influence of the fracture process zone on interfacial fracture toughness is determined using critical fracture toughness. All these may contribute to improvement of theory for SRHSHPC composite structure.

Empirical dependences for determination of parameters of geotextile containers

10.12737/3388 ◽  
2014 ◽  
Vol 2 (1) ◽  
pp. 38-42
Author(s):  
Александр Кравченко ◽  
Aleksandr Kravchenko
Keyword(s):  
High Strength ◽  
Determination Of Parameters

Empirical dependences for determination of parameters of flexible geotextile containers from high-strength polypropylene fabrics are received when moving commensurable with sizes of a design and relative deformations of a material to 20%.

Total organic carbon as a predictor of biological wastewater treatment efficiency and kinetic reaction rates

1997 ◽  
Vol 35 (8) ◽  
pp. 119-126 ◽  
Author(s):  
Francis Wilson
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Loading Rate ◽  
High Strength ◽  
Reaction Rates ◽  
Organic Loading Rate ◽  
Rotating Biological Contactor ◽  
Statistical Correlations ◽  
Input Parameters

The study investigated the use of Total Organic Carbon (TOC) to predict the efficiency of removal of a high strength wastewater and to obtain information about the kinetic processes in the rotating biological contactor system. For the determination of efficiency of removal, standard TOC analysis was used, and the results compared with those of the more usual BOD and COD tests. For the determination of the order of reaction, TOC alone was used. The results indicated that, for the high strength food processing wastewater being treated, the use of TOC gave excellent correlations between efficiency of removal and input parameters such as initial concentration, hydraulic loading rate and applied organic loading rate. The use of TOC also gave very high statistical correlations leading to an overall value for the order of reaction for the rotating biological contactor which agreed with previous research results. However, the value obtained for the order of the reaction was very dependent on the values of the input parameters which partly could be construed as showing evidence for the change from approximately first order to near zero order of reaction depending upon the input parameters.

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