Investigation into Impact of Column Rectangularity on Shear Strength of No-Stirrup Rc Members in General Shear

2010 ◽  
Vol 163-167 ◽  
pp. 1456-1459
Author(s):  
Da Ren ◽  
Chao Yang Zhou
Keyword(s):  
Shear Strength ◽  
Regression Analysis ◽  
Lower Bound ◽  
Failure Modes ◽  
Shear Failure ◽  
Unified Model ◽  
Design Equation ◽  
Physical Explanation ◽  
New Approach ◽  
Practical Concern

Based on the links among various shear failure modes and the unified model for beam-like shear and symmetrical punching previously proposed, a new approach is presented to allow for the effect of column rectangularity on the shear capacities of members in general shear, which includes punching and beam-like shear as two particular extremes. In succeeded regression analysis, linear metric form is selected out of practical concern, and a lower-bound design equation is finally developed that can not only measure the influence of this variable on members in general shear, but can give a clear physical explanation to the measurement, as is absent in certain codes.

scholarly journals Experimental Study and Failure Criterion Analysis on Combined Compression-Shear Performance of Self-Compacting Concrete

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 713 ◽  
Author(s):  
Jingrong Wang ◽  
Faxiang Xie ◽  
Chuanlong Zhang ◽  
Jing Ruan
Keyword(s):  
Residual Stress ◽  
Shear Strength ◽  
Axial Compression ◽  
Failure Modes ◽  
Shear Failure ◽  
Experimental Results ◽  
Compression Stress ◽  
Self Compacting Concrete ◽  
Cohesive Stress ◽  
Shear Performance

To investigate the combined compression-shear performance of self-compacting concrete (SCC), eight groups of concrete specimens under different axial compression ratios were designed, and the composite performance under different axial stresses was carried out by hydraulic servo machine. The uniaxial and tensile splitting strength of SCC were also included in the study. The failure modes of SCC were presented, discussed, and compared with normal concrete (NC). The characteristic points of stress-strain curves of SCC specimens from the experiments were extracted and analyzed under different axial compression stress. Based on the experimental results, the shear strength of compression-shear load was divided into cohesive stress and residual friction stress. The variation of residual stress and cohesive stress under the combined compression-shear stress was analyzed, and the relationship was obtained by numerical regression. Research results indicated that the residual stress increases linearly with the compression stress while the cohesive stress increased at first and then decreased. The research found that the friction coefficient of SCC was much smaller than NC due to the lack of interlocking effect. Utilizing the compression-shear strength of SCC, the material failure criteria of SCC were proposed from the view of shear failure strength and octahedral stress space, which could fit the experimental results confidently following the mathematical regression analysis. The comparison with data from other literature shows favorable consistence with the obtained criteria. The results of the study could be beneficial complement in engineering practices where SCC was applicable.

Copper, Silver, and PCC Wirebonds Reliability in Automotive Underhood Environments

2018 ◽  
Author(s):  
Pradeep Lall ◽  
Shantanu Deshpande ◽  
Luu Nguyen
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Failure Modes ◽  
Shear Failure ◽  
High Reliability ◽  
Electrical Response ◽  
Process Window ◽  
Mechanical Degradation ◽  
Electric Response ◽  
Trade Offs

Wire bonding is popular first-level interconnect method used in the semiconductor device packaging. Gold (Ag) wire is often used in high-reliability applications. Typical wire diameters vary between 0.8mil to 2mil. Recent increases in the gold-price have motivated the industry to search for alternate materials candidates for use in wirebonding. Three of the leading candidates are Silver (Ag), Copper (Cu), and Palladium Coated Copper (PCC). The new material candidates are inexpensive in comparison with gold and may have better electrical, and thermal properties, which is advantageous for fine pitch-high density electronics. The transition, however, comes along with few trade-offs such as narrow process window, higher wire-hardness, increased propensity for chip-cratering, lack of reliability knowledge base of when deployed in harsh environment applications. Relationship between mechanical degradation of the wirebond and the change in electric response needs to be established for better understanding of the failure modes and their respective mechanisms. Understanding the physics of damage progression may provide insights into the process parameters for manufacture of more robust interconnects. In this paper, a detailed study of the electrical and mechanical degradation of wirebonds under high temperature exposure is presented. Four wirebond candidates (Au, Ag, Cu and PCC) bonded onto Aluminum (Al) pad were subjected to high temperature storage life until failure to study the degradation of the bond-wire interface. Same package architecture and electronic molding compound (EMC) were used for all four candidates. Detailed analysis of intermetallic (IMC) phase evolution is presented along with quantification of the phases and their evolution over time. Ball shear strength was measured after decapsulation. Measurements of shear strength, shear failure modes, and IMC composition have been correlated with the change in the electrical response. Change in shear strength and different shear failure modes for different wirebond systems are discussed in the paper.

scholarly journals Shear strength of steel–concrete–steel sandwich deep beams: A simplified approach

2018 ◽  
Vol 22 (1) ◽  
pp. 42-53 ◽  
Author(s):  
Yubing Leng ◽  
Xiaobing Song
Keyword(s):  
Shear Strength ◽  
Analytical Model ◽  
Failure Modes ◽  
Shear Failure ◽  
Concrete Strength ◽  
Upper And Lower Bounds ◽  
Deep Beams ◽  
Concrete Core ◽  
Simplified Approach ◽  
Triangular Area

Steel–concrete–steel composite structure comprises a concrete core sandwiched between the outer steel plates. It combines the advantages of both steel and reinforced concrete structures. In thick steel–concrete–steel structural members, the shear performance becomes rather critical. Experimental works have been carried out to study the failure mode and shear strength of steel–concrete–steel deep beams, and an analytical model has been proposed. In this article, parametric studies are carried out on the original analytical model to discuss the influence of each geometric and material variable on the shear strength, and a simplified strength predicting method is developed. Different shear failure modes, identified as “top+bottom triangular area damage” or “bottom triangular area damage+horizontal cracking,” can be predicted with the method. The simplified approach shows good correlation with the experimental results, regarding to shear resisting pattern and failure modes. Through the simplified formulas, the upper and lower bounds of the shear resistance are obtained. The requirement on stud spacing to maintain full composite behavior in the top and bottom triangular areas and the requirement on concrete strength are proposed.

scholarly journals Experimental and numerical evaluations of composite concrete-to-concrete interfacial shear strength under horizontal and normal stresses

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0252050
Author(s):  
M. Yahya Al-Fasih ◽  
M. E. Mohamad ◽  
I. S. Ibrahim ◽  
Y. Ahmad ◽  
M. A. Mohd Ariffin ◽  
...  
Keyword(s):  
Shear Strength ◽  
Failure Mode ◽  
Failure Modes ◽  
Shear Failure ◽  
Zone Model ◽  
Normal Stresses ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Surface Textures ◽  
Roughened Surface

Effects of different surface textures on the interface shear strength, interface slip, and failure modes of the concrete-to-concrete bond are examined through finite element numerical model and experimental methods in the presence of the horizontal load with ‘push-off’ technique under different normal stresses. Three different surface textures are considered; smooth, indented, and transversely roughened to finish the top surfaces of the concrete bases. In the three-dimensional modeling via the ABAQUS solver, the Cohesive Zone Model (CZM) is used to simulate the interface shear failure. It is observed that the interface shear strength increases with the applied normal stress. The transversely roughened surface achieves the highest interface shear strength compared with those finished with the indented and smooth approaches. The smooth and indented surfaces are controlled by the adhesive failure mode while the transversely roughened surface is dominated by the cohesive failure mode. Also, it is observed that the CZM approach can accurately model the interface shear failure with 3–29% differences between the modeled and the experimental test findings.

scholarly journals Experimental Study on Mechanical Properties of Interface between Basalt Fiber-Reinforced Polymer/Glass Fiber-Reinforced Polymer Composite Cement Plate and Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Lifeng Zhang ◽  
Hui Liu ◽  
Wenqiang Li ◽  
Hangjun Liu ◽  
Xuehui An ◽  
...  
Keyword(s):  
Shear Strength ◽  
Failure Modes ◽  
Shear Failure ◽  
Concrete Strength ◽  
Concrete Block ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Reinforced Polymer ◽  
Composite Samples

The bonding behaviors of the plate-concrete interface of a composite structure consisting of a concrete block in the middle and two cement plates at both sides play a key role in its overall mechanical performance. In this paper, the authors conduct 3 groups of push-out shear tests on a total of 39 composite samples to assess the bonding performance. The influence of the FRP cement plates, the concrete strength, and the ribs installed in the cement plate on the interfacial shear strength, the relative bond-slip, strain, and the failure modes of the composite samples is recorded and analyzed. The results show that (1) the shear strength and bond-slip performance of the interface are largely improved if the GFRP/BRRP cement plates are used; (2) shear strength of the interface increases with the concrete strength, while the deformation behaviors show no significant improvement; (3) an inclusion of the ribs to the interface enhances the shear strength and shear stiffness but decreases the maximum relative slip at failure; (4) most of the samples present the shear failures along the interface; however, the bending shear failure prior to the interface shear failure is also observed on the concrete block for low concrete strength samples and the samples with ribs; and (5) regression method is used to develop a constitutive model of the stress-slip at the interface to describe the relationship between the shear strength with the cement plates, the concrete strength, and ribs.

The Shear Failure Modes and Anisotropy Based on the Shear Strength Theory in Classical Solid Mechanics

2013 ◽  
Vol 387 ◽  
pp. 164-167
Author(s):  
Shao Hua Guo
Keyword(s):  
Shear Strength ◽  
Solid Mechanics ◽  
Failure Modes ◽  
Shear Failure ◽  
Strength Theory ◽  
Standard Space

The shear failure modes of anisotropic solids are studied here based on the elastic standard space of physical presentation, some new shear failure phenomena for anisotropic solids are presented. The relations between shear failure modes and anisotropy are discussed. The results show that there are obvious differences in shear failure modes for different anisotropic solids.

scholarly journals Effect of Corrosion in the Transverse Reinforcements in Concrete Beams: Sustainable Method to Generate and Measure Deterioration

2020 ◽  
Vol 12 (19) ◽  
pp. 8105
Author(s):  
P. Castro-Borges ◽  
C. A. Juárez-Alvarado ◽  
R. I. Soto-Ibarra ◽  
J. A. Briceño-Mena ◽  
G. Fajardo-San Miguel ◽  
...  
Keyword(s):  
Shear Strength ◽  
Failure Modes ◽  
Shear Failure ◽  
Corrosion Potential ◽  
Concrete Beams ◽  
Ultimate Shear Strength ◽  
Cross Sectional ◽  
Mass Losses ◽  
Consistent Method ◽  
Theoretical Results

A consistent method to generate and measure deterioration by corrosion in transverse reinforcements for concrete beams is presented and discussed in this work. This approach could be applied in other circumstances, such as bending, compression or combinations of stresses, with comparable results and therefore can be used to ensure sustainability. In marine environments, macro-cells are produced primarily from a transverse reinforcement, which works as an anode and therefore becomes a critical part of the structural analysis. To evaluate the adaptation efficiency of our proposed method, the corrosion potential, mass losses and cross-section reductions of the steel were measured. The shear stress behavior of the beams was investigated, including beam responses to load deformations, failure modes and cracking. The method ensured that all the beams exhibited a shear failure from diagonal stress with almost 50% less deflection when mechanically tested. The critical cross-sectional area, calculated according to the experimental diameter with the greatest cross-sectional loss due to the corrosion of the deteriorated stirrup, proved to be a reliable value for predicting the ultimate shear strength of concrete beams deteriorated by severe corrosion. A reduction of up to 30% in the shear strength of deteriorated versus non-deteriorated beams was found. Additional results showed that there is a correlation between the experimental and theoretical results and that the method is reproducible.

scholarly journals Influence of Bond Behaviour of Flexural GFRP Reinforcement on Failure Mechanisms in Beams Without Stirrups

2018 ◽  
Vol 64 (4) ◽  
pp. 269-283
Author(s):  
M. Kaszubska ◽  
R. Kotynia
Keyword(s):  
Shear Strength ◽  
Failure Mode ◽  
Failure Modes ◽  
Shear Failure ◽  
Shear Crack ◽  
Failure Mechanisms ◽  
Crack Pattern ◽  
Critical Crack ◽  
Bond Behaviour ◽  
Gfrp Bars

AbstractThe aim of the paper is to investigate the shear failure mechanisms in T-shape, single span and simply supported beams exclusively reinforced with longitudinal glass fiber reinforced polymer (GFRP) bars. Usually the critical shear crack in RC beams without stirrups develops through the theoretical compression strut reducing the shear strength following the shear failure. The main parameter affecting the crack pattern and the shear strength of the beams is the shear slenderness. However, the test results presented in the paper indicated the new arching effect due to the bond losing between the GFRP flexural reinforcement and concrete. This failure mode revealed unexpected critical crack pattern and failure mode. The research of concrete beams flexurally reinforced with GFRP bars without stirrups indicated two failure modes: typical shear-compression and a new one leading by the bond losing between the ordinary reinforcement and concrete.

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