Experimental Research on Four-Tube Concrete-Filled Steel Tubular Laced Columns

2011 ◽  
Vol 311-313 ◽  
pp. 2204-2207 ◽  
Author(s):  
Bo Wang Chen ◽  
Ran He ◽  
Jian Guo Tan ◽  
Yang Oyang
Keyword(s):  
Mechanical Properties ◽  
Yield Point ◽  
Experimental Research ◽  
Failure Modes ◽  
Shear Failure ◽  
Short Columns ◽  
Eccentric Compression ◽  
Bending Failure ◽  
Overall Bending ◽  
Compressive Tests

By means of axial compressive and eccentric compressive tests of four Four-tube Concrete-filled Steel Tubular Laced Columns, to research the mechanical properties and failure modes of this structural without yield point. Research shows that, the failure modes of this model, as well as axial compressive short columns, have the same trend of oblique shear failure, and presenting overall bending failure under eccentric compression. The linear eccentricity takes a biggish influence on mechanical properties of laced columns.

Experimental Research on Joints Behavior of Concrete-Filled Steel Tubular Columns

2013 ◽  
Vol 446-447 ◽  
pp. 1409-1412
Author(s):  
Mei Li He ◽  
Hua Long Yu ◽  
Yan Cao ◽  
Yong Kang Xia
Keyword(s):  
Mechanical Properties ◽  
Yield Point ◽  
Experimental Research ◽  
Failure Modes ◽  
Shear Failure ◽  
Tubular Columns ◽  
Short Columns ◽  
Compressive Tests

By means of eccentric compressive tests of Concrete-filled Steel Tubular Columns, to research the mechanical properties and failure modes of Concrete-filled Steel Tubular Columns without yield point. Research shows that, the failure modes of axial compressive Concrete-filled Steel Tubular Columns without yield point, as well as axial compressive short columns, have the same trend of oblique shear failure.

Test on Eccentricaly Loaded Four-Tube Concrete-Filled Steel Tubular (CFST) Laced Columns of No Yield Point

2012 ◽  
Vol 204-208 ◽  
pp. 4658-4663 ◽  
Author(s):  
Ran He ◽  
Xing Ping Shu ◽  
Bo Wang Chen
Keyword(s):  
Yield Point ◽  
Axial Compression ◽  
Ductile Failure ◽  
Confinement Effect ◽  
Eccentric Compression ◽  
Global Deformation ◽  
Bending Failure ◽  
Overall Bending

In order to study the characteristics about deformation and stress of four-tube concrete-filled steel tubular(CFST) laced columns of no yield point, a test with the parameter of eccentricity on two our-tube concrete-filled steel tubular(CFST) laced columns of no yield point has been finished by means of 500t press. The results of the test shows that the larger the eccentricity, the more obvious the global deformation of laced columns tends to become, and the four-tube CFST laced columns of no yield point under eccentric compression were subjected to overall bending failure and ductile failure with obvious premonition; In the meanwhile, confinement effect of main tubes away from the loading point of laced columns under eccentric compression was inapparent , while confinement effect of the two main tubes close to the loading point begain to play and increase before it was to fail, which made the characteristics about deformation and stress of the the two main tubes close to the loading point similar to the single CFST column under axial compression.

scholarly journals Behavior of the T-Shaped Concrete-Filled Steel Tubular Columns after Elevated Temperature

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Xianglong Liu ◽  
Jicheng Zhang ◽  
Hailin Lu ◽  
Ning Guan ◽  
Jiahao Xiao ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Shear Failure ◽  
Element Model ◽  
Ultimate Bearing Capacity ◽  
Steel Tubes ◽  
Tubular Columns ◽  
Short Columns ◽  
Experimental Values

The mechanical properties of T-shaped concrete-filled steel tubular (TCFST) short columns under axial compression after elevated temperature are investigated in this paper. A total of 30 TCFST short columns with different temperature (T), steel ratio (α), and duration of heating (t) were tested. The TCFST column was directly fabricated by welding two rectangular steel tubes together. The study mainly investigated the failure modes, the ultimate bearing capacity, the load-displacement, and the load-strain performance of the TCFST short columns. Experimental results indicate that the rectangular steel tubes of the TCFST column have deformation consistency, and the failure mode consists of local crack, drum damage, and shear failure. Additionally, the influence of high temperature on the residual bearing capacity of the TCFST is significant, e.g., a higher temperature can downgrade the ultimate bearing capacity. Finally, a finite element model (FEM) is developed to simulate the performance of the TCFST short columns under elevated temperature, and the results agree with experimental values well. Overall, this investigation can provide some guidance for future studies on damage assessment and reinforcement of the TCFST columns.

Experimental investigation and modeling of dynamic thermomechanical behavior of 4-harness satin weave carbon/epoxy composites

2017 ◽  
Vol 31 (9) ◽  
pp. 1181-1203 ◽  
Author(s):  
Xueyao Hu ◽  
Hui Guo ◽  
Weiguo Guo ◽  
Feng Xu ◽  
Longyang Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Composite Laminates ◽  
Failure Modes ◽  
Shear Failure ◽  
Experimental Studies ◽  
Temperature Shift ◽  
Thermomechanical Coupling ◽  
Longitudinal Splitting ◽  
Wide Range

Theoretical and experimental studies on the compressive mechanical behavior of 4-harness satin weave carbon/epoxy composite laminates under in-plane loading are conducted over the temperature range of 298–473 K and the strain rate range of 0.001–1700/s in this article. The stress–strain curves of 4-harness satin weave composites are obtained at different strain rates and temperatures, and key mechanical properties of the material are determined. The deformation mechanism and failure morphology of the samples are observed and analyzed by scanning electron microscope (SEM) micrographs. The results show that the uniaxial compressive mechanical properties of 4-harness satin weave composites are strongly dependent on the temperature but are weakly sensitive to strain rate. The peak stress and elastic modulus of the material have the trend of decrease with the increasing of temperature, and the decreasing trend can be expressed as the functional relationship of temperature shift factor. In addition, SEM observations show that the quasi-static failure mode of 4-harness satin weave composites is shear failure along the diagonal lines of the specimens, while the dynamic failure modes of the material are multiple delaminations and longitudinal splitting, and with the increasing of temperature, its longitudinal splitting is more serious, but the delamination is relatively reduced. A constitutive model with thermomechanical coupling effects is proposed based on the experimental results and the increment theory of elastic–plastic mechanics. The experimental verification and numerical analysis show that the model is shown to be able to predict the finite deformation behavior of 4-harness satin weave composites over a wide range of temperatures.

scholarly journals Cracking Behaviors and Mechanical Properties of Rock-Like Specimens with Two Unparallel Flaws under Conventional Triaxial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Huilin Le ◽  
Shaorui Sun ◽  
Chenghua Xu ◽  
Liuyang Li ◽  
Yong Liu
Keyword(s):  
Mechanical Properties ◽  
Inclination Angle ◽  
Failure Modes ◽  
Shear Failure ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Critical Value ◽  
Tensile Failure ◽  
Rock Bridge ◽  
Bridge Length

Flaws existing in rock masses are generally unparallel and under three-dimensional stress; however, the mechanical and cracking behaviors of the specimens with two unparallel flaws under triaxial compression have been rarely studied. Therefore, this study conducted comprehensive research on the cracking and coalescence behavior and mechanical properties of specimens with two unparallel flaws under triaxial compression. Triaxial compressive tests were conducted under different confining pressures on rock-like specimens with two preexisting flaws but varying flaw geometries (with respect to the inclination angle of the two unparallel flaws, rock bridge length, and rock bridge inclination angle). Six crack types and eleven coalescence types in the bridge region were observed, and three types of failure modes (tensile failure, shear failure, and tensile-shear failure) were observed in experiments. Test results show that bridge length and bridge inclination angle have an effect on the coalescence pattern, but the influence of bridge inclination angle is larger than that of the bridge length. When the confining pressure is low, coalescence patterns and failure modes of the specimens are greatly affected by flaw geometry, but when confining pressure rose to a certain level, the influence of confining pressure is larger than the effect of flaw geometry. The peak strength of the specimens is affected by flaw geometry and confining pressure. There is a critical value for the bridge length. If the bridge length is larger than the critical value, peak strengths of the samples almost keep constant as the bridge length increases. In addition, as the bridge inclination angle increases, there is an increase in the probability of tensile cracks occurring, and with an increase in the confining pressure, the probability of the occurrence of shear cracks increases.

scholarly journals Determination of Scale Effects on Mechanical Properties of Berea Sandstone

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Hui Li ◽  
Kaoping Song ◽  
Mingguang Tang ◽  
Ming Qin ◽  
Zhenping Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Poisson’S Ratio ◽  
Failure Modes ◽  
Shear Failure ◽  
Scale Effects ◽  
Poisson's Ratio ◽  
Axial Splitting ◽  
Rock Mechanical Properties

The key rock mechanical parameters are strength, elastic modulus, Poisson’s ratio, etc., which are important in reservoir development. The accurate determination of reservoir’s mechanical properties is critical to reduce drilling risk and maximize well productivity. Precisely estimating rock mechanical properties is important in drilling and well completion design, as well as crucial for hydraulic fracturing. Rocks are heterogeneous and anisotropic materials. The mechanical properties vary not only with rock types but also with measurement methods, sample geometric dimensions (sample length to diameter ratio and size), and other factors. To investigate sample scale effects on rock mechanical behaviors, unconfined compression tests were conducted on 41 different geometric dimensions of Berea sandstones; unconfined compressive strength (UCS), Young’s modulus ( E ), Poisson’s ratio ( υ ), bulk modulus ( K ), and shear modulus ( G ) were obtained and compared. The results indicate that sample geometry can significantly affect rock mechanical properties: (1) UCS decreases with the increase of length to diameter ratio (LDR), and the UCS standardize factor is between 0.71 and 1.17, which means -30% to +20% variation of UCS with LDR changing from 1 to 6.7. The test results show UCS exhibits positive relationship with sample size. (2) Young’s modulus slightly increases with LDR increases, while Poisson’s ratio decreases with the increase of LDR. For the tested Berea sandstones, Poisson’s ratio standardizing factor is between 0.57 and 1.11. (3) Bulk modulus of Berea sandstone samples decreases with the increase of LDR, while shear modulus increases with LDR increases. Both bulk modulus and shear modulus increase with the increase of sample size. (4) The principal failure modes were analyzed. The failure modes of the tested Berea sandstones are axial splitting and shear failure. Stocky samples ( LDR < 2 ) tend to go axial splitting, while slender samples ( LDR > 2 ) tend to show shear failure.

scholarly journals Categorization of Failures in Polymer Rapid Tools Used for Injection Molding

Processes ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 17 ◽  
Author(s):  
Anurag Bagalkot ◽  
Dirk Pons ◽  
Digby Symons ◽  
Don Clucas
Keyword(s):  
Injection Molding ◽  
Tool Life ◽  
Failure Modes ◽  
Shear Failure ◽  
Cost Effective ◽  
Critical Parameters ◽  
Cost Effective Method ◽  
Edge Failure ◽  
Underlying Mechanisms ◽  
Bending Failure

Background—Polymer rapid tooling (PRT) inserts for injection molding (IM) are a cost-effective method for prototyping and low-volume manufacturing. However, PRT inserts lack the robustness of steel inserts, leading to progressive deterioration and failure. This causes quality issues and reduced part numbers. Approach—Case studies were performed on PRT inserts, and different failures were observed over the life of the tool. Parts molded from the tool were examined to further understand the failures, and root causes were identified. Findings—Critical parameters affecting the tool life, and the effect of these parameters on different areas of tool are identified. A categorization of the different failure modes and the underlying mechanisms are presented. The main failure modes are: surface deterioration; surface scalding; avulsion; shear failure; bending failure; edge failure. The failure modes influence each other, and they may be connected in cascade sequences. Originality—The original contributions of this work are the identification of the failure modes and their relationships with the root causes. Suggestions are given for prolonging tool life via design practices and molding parameters.

scholarly journals Failure mechanism of hollow tree trunks due to cross-sectional flattening

2017 ◽  
Vol 4 (4) ◽  
pp. 160972 ◽  
Author(s):  
Yan-San Huang ◽  
Fu-Lan Hsu ◽  
Chin-Mei Lee ◽  
Jia-Yang Juang
Keyword(s):  
Urban Areas ◽  
Failure Modes ◽  
Shear Failure ◽  
Maximum Shear Stress ◽  
Mode Iii ◽  
Buckling Mode ◽  
Cross Sectional ◽  
Longitudinal Splitting ◽  
Bending Failure ◽  
Hollow Tree

Failure of hollow trees in urban areas is a worldwide concern, and it can be caused by different mechanisms, i.e. bending stresses or flattening-related failures. Here we derive a new analytical expression for predicting the bending moment for tangential cracking, and compare the breaking moment of various failure modes, including Brazier buckling, tangential cracking, shear failure and conventional bending failure, as a function of t / R ratio, where t and R are the trunk wall thickness and trunk radius, respectively, of a hollow tree. We use Taiwan red cypress as an example and show that its failure modes and the corresponding t / R ratios are: Brazier buckling (Mode I), tangential cracking followed by longitudinal splitting (Mode II) and conventional bending failure (Mode III) for 0 <  t / R  < 0.06, 0.06 <  t / R  < 0.27 and 0.27 <  t / R  < 1, respectively. The exact values of those ratios may vary within and among species, but the variation is much smaller than individual mechanical properties. Also, shear failure, another type of cracking due to maximum shear stress near the neutral axis of the tree trunk, is unlikely to occur since it requires much larger bending moments. Hence, we conclude that tangential cracking due to cross-sectional flattening, followed by longitudinal splitting, is dominant for hollow trunks. Our equations are applicable to analyse straight hollow tree trunks and plant stems, but are not applicable to those with side openings or those with only heart decay. Our findings provide insights for those managing trees in urban situations and those managing for conservation of hollow-dependent fauna in both urban and rural settings.

scholarly journals Experimental Investigation on Failure Modes and Mechanical Properties of Rock-Like Specimens with a Grout-Infilled Flaw under Triaxial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Huilin Le ◽  
Shaorui Sun ◽  
Feng Zhu ◽  
Haotian Fan
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Epoxy Resin ◽  
Failure Modes ◽  
Shear Failure ◽  
Fractured Rock ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Confining Pressure ◽  
Compression Tests

Flaws existing in rock mass are one of the main factors resulting in the instability of rock mass. Epoxy resin is often used to reinforce fractured rock mass. However, few researches focused on mechanical properties of the specimens with a resin-infilled flaw under triaxial compression. Therefore, in this research, epoxy resin was selected as the grouting material, and triaxial compression tests were conducted on the rock-like specimens with a grout-infilled flaw having different geometries. This study draws some new conclusions. The high confining pressure suppresses the generation of tensile cracks, and the failure mode changes from tensile-shear failure to shear failure as the confining pressure increases. Grouting with epoxy resin leads to the improvement of peak strengths of the specimens under triaxial compression. The reinforcement effect of epoxy resin is better for the specimens having a large flaw length and those under a relatively low confining pressure. Grouting with epoxy resin reduces the internal friction angle of the samples but improves their cohesion. This research may provide some useful insights for understanding the mechanical behaviors of grouted rock masses.

Seismic Experiments for Multi-Ribbed Sandwich Insulation Composite Wallboard

2012 ◽  
Vol 174-177 ◽  
pp. 701-705
Author(s):  
Ya Feng Yue ◽  
Wei Huang ◽  
Dong Zhao
Keyword(s):  
Mechanical Properties ◽  
Energy Dissipation ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Shear Failure ◽  
Low Frequency ◽  
Ultimate Bearing Capacity ◽  
Horizontal Load ◽  
Initial Stiffness

Low frequency cyclic horizontal load experiments have been carried out on the sandwich insulation (ECW-8) and ordinary (ECW-1) multi-ribbed composite wallboard. Mechanical properties of two specimens such as bearing capacity, energy dissipation and failure modes were studied. Two specimens are both shear failure. The cracking load of insulation wallboard increases by 29.1% than ordinary wallboard. The initial stiffness of insulation wallboard is 1.38 times of ordinary wallboard. The ultimate bearing capacity and energy dissipation performance has little difference between them.

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