scholarly journals Shear Stress-Relative Slip Relationship at Concrete Interfaces

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Keun-Hyeok Yang
Keyword(s):  
Shear Stress ◽  
Substrate Surface ◽  
Peak Stress ◽  
Upper Bound Theorem ◽  
Relative Slip ◽  
Proposed Model ◽  
Bound Theorem ◽  
Shear Cracking ◽  
S Model ◽  
Relationship Of

This study develops a simple and rational shear stress-relative slip model of concrete interfaces with monolithic castings or smooth construction joints. In developing the model, the initial shear cracking stress and relative slip amount at peak stress were formulated from a nonlinear regression analysis using test data for push-off specimens. The shear friction strength was determined from the generalized equations on the basis of the upper-bound theorem of concrete plasticity. Then, a parametric fitting analysis was performed to derive equations for the key parameters determining the shapes of the ascending and descending branches of the shear stress-relative slip curve. The comparisons of predictions and measurements obtained from push-off tests confirmed that the proposed model provides superior accuracy in predicting the shear stress-relative slip relationship of interfacial shear planes. This was evidenced by the lower normalized root mean square error than those in Xu et al.’s model and the CEB-FIB model, which have many limitations in terms of the roughness of the substrate surface along an interface and the magnitude of equivalent normal stress.

scholarly journals Mechanical Model for Shear Friction Capacity of Concrete at Construction Joints

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Seung-Jun Kwon ◽  
Keun-Hyeok Yang ◽  
Ju-Hyun Mun
Keyword(s):  
Mechanical Model ◽  
Test Results ◽  
Upper Bound Theorem ◽  
Shear Transfer ◽  
Strut And Tie ◽  
Proposed Model ◽  
Shear Friction ◽  
Bound Theorem ◽  
Construction Joints ◽  
Interfacial Plane

This study examined the reliability and limitations of code equations for determining the shear friction strength of a concrete interface with construction joints. This was achieved by examining the code equations (ACI 318-14, AASHTO, and fib 2010) and comparing the results predicted by equations with experimental data compiled from 207 push-off specimens (133 rough and 74 smooth construction joints). The integrated mechanical model for the monolithic interface, derived from the upper-bound theorem of concrete plasticity, was also modified to estimate the shear friction strength of the construction joints. The upper limit for shear friction strength was formulated from a concrete crushing failure limit on the strut-and-tie action along the interfacial plane, to avoid overestimating the shear transfer capacity of transverse reinforcement with a high clamping force. Code equations are highly conservative and dispersive in predicting the shear friction strength of rough construction joints and yield large scattering in the data for the ratios between the measured and predicted shear friction strengths. The predictions obtained using the proposed model agreed well with test results, indicating correlating trends with the test results for evaluating the effects of various parameters on the shear friction strength of rough construction joints. According to the proposed model, the values of cohesion and coefficient of friction for concrete could be determined as 0.11 fc′0.65 and 0.64, respectively, for smooth construction joints and 0.27 fc′0.65 and 0.95, respectively, for rough construction joints, where fc′ is the compressive strength of concrete.

Mathematical Model for Shear Stress-Strain Relationship of Soil-Concrete Interface during Shear Fracture Process

2007 ◽  
Vol 348-349 ◽  
pp. 881-884 ◽  
Author(s):  
Wei Wang ◽  
Ting Hao Lu ◽  
Bin Xiang Sun
Keyword(s):  
Shear Stress ◽  
Fracture Process ◽  
Shear Fracture ◽  
Hyperbolic Model ◽  
Stress Strain ◽  
Numerical Studies ◽  
Proposed Model ◽  
Strain Relationship ◽  
Relationship Of ◽  
Concrete Interface

Description of shear stress-strain relationship for soil-concrete interface during shear fracture process plays an important role in experimental and numerical studies of soil-structure interaction. In this paper, deficiency of traditional hyperbolic model for the shear stress-strain relationship is analyzed, firstly. Then, a new model with 3 parameters for it is established, which can overcome the deficiency of hyperbolic model. Finally, good agreements have been found between the proposed model and laboratory tests.

The Constitutive Model for High Temperature Flow Behavior of SiC/6168Al Composite

2015 ◽  
Vol 1089 ◽  
pp. 37-41
Author(s):  
Jiang Wang ◽  
Sheng Li Guo ◽  
Sheng Pu Liu ◽  
Cheng Liu ◽  
Qi Fei Zheng
Keyword(s):  
Constitutive Model ◽  
Hot Deformation ◽  
Flow Behavior ◽  
Type Equation ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Stress Strain ◽  
Hollomon Parameter ◽  
Proposed Model ◽  
Relationship Of

The hot deformation behavior of SiC/6168Al composite was studied by means of hot compression tests in the temperature range of 300-450 °C and strain rate range of 0.01-10 s-1. The constitutive model was developed to predict the stress-strain curves of this composite during hot deformation. This model was established by considering the effect of the strain on material constants calculated by using the Zenter-Hollomon parameter in the hyperbolic Arrhenius-type equation. It was found that the relationship of n, α, Q, lnA and ε could be expressed by a five-order polynomial. The stress-strain curves obtained by this model showed a good agreement with experimental results. The proposed model can accurately describe the hot flow behavior of SiC/6168Al composite, and can be used to numerically analyze the hot forming processes.

Selection of the Optimal Distribution for the Upper Bound Theorem in Indentation Processes

2014 ◽  
Vol 797 ◽  
pp. 117-122 ◽  
Author(s):  
Carolina Bermudo ◽  
F. Martín ◽  
Lorenzo Sevilla
Keyword(s):  
Upper Bound ◽  
Geometric Distribution ◽  
Optimal Choice ◽  
Optimal Distribution ◽  
Upper Bound Theorem ◽  
Modular Model ◽  
Bound Theorem ◽  
Rigid Zones ◽  
Dimensionless Relation ◽  
Selection Of

It has been established, in previous studies, the best adaptation and solution for the implementation of the modular model, being the current choice based on the minimization of the p/2k dimensionless relation obtained for each one of the model, analyzed under the same boundary conditions and efforts. Among the different cases covered, this paper shows the study for the optimal choice of the geometric distribution of zones. The Upper Bound Theorem (UBT) by its Triangular Rigid Zones (TRZ) consideration, under modular distribution, is applied to indentation processes. To extend the application of the model, cases of different thicknesses are considered

scholarly journals Compressive Test Characteristics and Constitutive Relationship of Wet Polypropylene Macrofiber-Reinforced Shotcrete

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Fenghui Li ◽  
Yunhai Cheng ◽  
Fei Wu ◽  
Chang Su ◽  
Gangwei Li
Keyword(s):  
Mechanical Response ◽  
Average Energy ◽  
Strain Curve ◽  
Peak Stress ◽  
Constitutive Relationship ◽  
Compression Tests ◽  
Response Characteristics ◽  
Test Characteristics ◽  
High Crack ◽  
Relationship Of

Shotcrete is often subject to poor ductility and cracking problems, particularly under high stresses. In order to deal with these issues, the feasibility of adding polypropylene macrofibers to shotcrete was verified. To ascertain the supporting effect, dry shotcrete, wet shotcrete, and wet polypropylene macrofiber-reinforced shotcrete (WPMS) were used as samples. Furthermore, the mechanical response characteristics thereof in uniaxial compression tests were compared and analyzed by acoustic emission (AE) monitoring. The results showed that the three materials were brittle, but the ductility, residual strength, and bearing capacity of polypropylene macrofiber-reinforced shotcrete were significantly enhanced. The energy absorption value of plain shotcrete was higher in the cracking stage, while that of polypropylene macrofiber-reinforced shotcrete was greater in the postpeak stage, which showed that the polypropylene macrofiber-reinforced shotcrete had the characteristics of a high crack-initiation strength and toughness. Besides, the energy release from fiber shotcrete occurred after the peak stress rather than near the peak stress. The average energy absorbed by polypropylene macrofiber-reinforced shotcrete was significantly higher than that in dry shotcrete and wet shotcrete, which implied that polypropylene macrofiber-reinforced shotcrete could mitigate the brittle instability of a shotcrete layer. A constitutive model of damage statistics was established based on the test data. The comparison between the experimental data and the fitting results can reflect the characteristics of the total stress-strain curve of such shotcrete. The results provide a basis for the optimization of polypropylene macrofiber-reinforced shotcrete layers.

Upper Bound Solutions to Plane-Strain Extrusion Problems

1970 ◽  
Vol 92 (1) ◽  
pp. 158-164 ◽  
Author(s):  
P. C. T. Chen
Keyword(s):  
Plane Strain ◽  
Upper Bound ◽  
Material Properties ◽  
Incompressible Material ◽  
Velocity Fields ◽  
Deformation Pattern ◽  
Upper Bound Theorem ◽  
Admissible Velocity ◽  
Die Geometry ◽  
Bound Theorem

A method for selecting admissible velocity fields is presented for incompressible material. As illustrations, extrusion processes through three basic types of curved dies have been treated: cosine, elliptic, and hyperbolic. Upper-bound theorem is used in obtaining mean extrusion pressures and also in choosing the most suitable deformation pattern for extrusion through square dies. Effects of die geometry, friction, and material properties are discussed.

Business Oriented Systems Maintenance Management

2011 ◽  
pp. 326-344 ◽  
Author(s):  
Malin Nordstrom ◽  
Tommy Welander
Keyword(s):  
Business Processes ◽  
Practical Experience ◽  
Theoretical Research ◽  
It Systems ◽  
Proposed Model ◽  
System Maintenance ◽  
Systems Maintenance ◽  
Business Changes ◽  
Business Needs ◽  
Relationship Of

In the introduction to this chapter, we discuss some of the common problems in maintenance. In order to solve these problems, we find it necessary to think in a new way, including the relationship of businesses to the system maintenance. The world outside organisations changes continuously, and the business processes and functions must change with it. However, if we only maintain information technology (IT) and do not co-manage the business changes accordingly, IT will not change at the same pace as the business changes. It would result a gap between the business needs and services provided by the IT product. In that case, IT systems would not be able to provide sufficient business value. The main part of this chapter contains a management model for solving these problems, based on theoretical research and practical experience. The central theme of the model is the connection between the business needs and systems maintenance. This is achieved by maintaining maintenance objects rather than the systems, establishing micro-organisations for each maintenance object where business processes as well as the system are represented. Our proposed model is widely used in more than 50 organisations in Sweden. In conclusion, some future trends and central concepts of the model are discussed.

Hardening effect analysis in indentation processes by modular configuration of the upper bound theorem

2017 ◽  
Vol 10 (1) ◽  
pp. 59
Author(s):  
Carolina Bermudo Gamboa ◽  
Francisco De Sales Martín Fernández ◽  
Lorenzo Sevilla Hurtado
Keyword(s):  
Upper Bound ◽  
Upper Bound Theorem ◽  
Effect Analysis ◽  
Hardening Effect ◽  
Bound Theorem
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