scholarly journals Influence of Fissure Number on the Mechanical Properties of Layer-Crack Rock Models under Uniaxial Compression

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yun-liang Tan ◽  
Wei-yao Guo ◽  
Tong-bin Zhao ◽  
Feng-hai Yu ◽  
Bin Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bearing Capacity ◽  
Failure Mechanism ◽  
Uniaxial Compression ◽  
Rational Design ◽  
Failure Modes ◽  
Test Results ◽  
Active Stage ◽  
Engineering Project ◽  
Nonuniform Deformation

Many case studies have revealed that rock bursts generally occur in the high stress concentration area where layer-crack structures often exist, especially for brittle coal or rock masses. Understanding the mechanical properties of layer-crack rock models is beneficial for rational design and stability analysis of rock engineering project and rock burst prevention. This study experimentally investigated the influence of fissure number on the mechanical properties of layer-crack rock models through uniaxial compression tests. The digital speckle correlation method (DSCM) and acoustic emission (AE) techniques were applied to record and analyze the information of deformation and failure processes. Test results show the following: the bearing capacity of layer-crack specimen decreases compared with intact specimen, but their failure modes are similar, which are the splitting failure accompanied with local shear failure; the nonuniform deformation phenomenon begins to appear at the elastic deformation stage for layer-crack specimens; the AE behavior of intact specimens consists of three stages, that is, active stage, quiet stage, and major active stage, but for layer-crack specimens, it is characteristic by three peaks without quiet stage. In addition, as the fissure number of layer-crack specimens increases, the bearing capacity of specimens decreases, the appearing time of nonuniform deformation phenomenon in the specimen surface decreases, the AE events are denser and denser in each peak stage, and the risk of dynamic instability of layer-crack structure increases. At last, the failure mechanism of layer-crack structure and the related mitigation advices were discussed based on the test results. In general, the novelty is that this paper focuses on the failure mechanism of layer-crack structure directly.

scholarly journals Flexural bearing capacity and failure mechanism of CFRP-aluminum laminate beam with double-channel cross-section

2021 ◽  
Vol 28 (1) ◽  
pp. 139-152
Author(s):  
Teng Huang ◽  
Dongdong Zhang ◽  
Yaxin Huang ◽  
Chengfei Fan ◽  
Yuan Lin ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Bearing Capacity ◽  
Failure Mechanism ◽  
Cross Section ◽  
Failure Criterion ◽  
Failure Modes ◽  
Channel Cross Section ◽  
Fiber Layer ◽  
Flexural Bearing Capacity ◽  
Double Channel

Abstract In this study, the flexural bearing capacity and failure mechanism of carbon fiber-reinforced aluminum laminate (CARALL) beams with a double-channel cross-section and a 3/2 laminated configuration were experimentally and numerically studied. Two types of specimens using different carbon fiber layup configurations ([0°/90°/0°]3 and [45°/0°/−45°]3) were fabricated using the pressure molding thermal curing forming process. The double-channel CARALL beams were subjected to static three-point bending tests to determine their failure behaviors in terms of ultimate bearing capacity and failure modes. Owing to the shortcomings of the two-dimensional Hashin failure criterion, the user-defined FORTRAN subroutine VUMAT suitable for the ABAQUS/Explicit solver and an analysis algorithm were established to obtain a progressive damage prediction of the CFRP layer using the three-dimensional Hashin failure criterion. Various failure behaviors and mechanisms of the CARALL beams were numerically analyzed. The results indicated that the numerical simulation was consistent with the experimental results for the ultimate bearing capacity and final failure modes, and the failure process of the double-channel CARALL beams could be revealed. The ultimate failure modes of both types of double-channel CARALL beams were local buckling deformation at the intersection of the upper flange and web near the concentrated loading position, which was mainly caused by the delamination failure among different unidirectional plates, tension and compression failure of the matrix, and shear failure of the fiber layers. The ability of each fiber layer to resist damage decreased in the order of 90° fiber layer > 0° fiber layer > 45° fiber layer. Thus, it is suggested that 90°, 0°, and 45° fiber layers should be stacked for double-channel CARALL beams.

scholarly journals Tests and Analyses of Slotted-In Steel-Plate Connections in Composite Timber Shear Wall Panels

2017 ◽  
Vol 2017 ◽  
pp. 1-20
Author(s):  
Ulf Arne Girhammar ◽  
Bo Källsner
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Design Method ◽  
Shear Walls ◽  
Test Results ◽  
Horizontal Shear ◽  
Load Bearing Capacity ◽  
Wood Panel ◽  
Load Bearing ◽  
Plate Connections

The authors present an experimental and analytical study of slotted-in connections for joining walls in the Masonite flexible building (MFB) system. These connections are used for splicing wall elements and for tying down uplifting forces and resisting horizontal shear forces in stabilizing walls. The connection plates are inserted in a perimeter slot in the PlyBoard™ panel (a composite laminated wood panel) and fixed mechanically with screw fasteners. The load-bearing capacity of the slotted-in connection is determined experimentally and derived analytically for different failure modes. The test results show ductile postpeak load-slip characteristics, indicating that a plastic design method can be applied to calculate the horizontal load-bearing capacity of this type of shear walls.

scholarly journals Failure Mechanism of a Coal-Rock Combined Body with Inclinations of Structural Planes and a Calculation Model for Impact Energy

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Yi-Chao Zhao ◽  
Ming-Shi Gao ◽  
Yong-Liang He ◽  
Dong Xu
Keyword(s):  
Mechanical Properties ◽  
Failure Mechanism ◽  
Impact Energy ◽  
Coal Mines ◽  
Calculation Model ◽  
Engineering Practice ◽  
Test Results ◽  
Failure Characteristics ◽  
Coal Rock ◽  
Rock Strata

A coal-rock (CR) combined body can be used to simulate structures of coal and rock strata, and its impact-induced failure characteristic conforms more close to engineering practice. Exploring the mechanical properties and impact energy in a CR combined body contributes to better predictions of rock bursts in coal mines. In the study, the mechanical properties of CR combined bodies with four different inclinations (0°, 15°, 30°, and 45°) of structural planes were measured, and also their failure mechanism was analysed. Based on the theory of particle mechanics, a calculation model for impact energy in a CR combined body with inclinations was established and then verified by using monitored acoustic emission (AE) data. The test results showed that inclination affected mechanical properties and failure characteristics of the CR combined body, i.e., the larger the inclination, the lower the strength and impact energy in the CR combined body and the lower the level of damage. The proposed calculation model for impact energy revealed the mechanical essence of energy accumulation and release of a CR combined body, providing a reference for investigating rock burst in coal mines.

Assesment of Main Models for Predicting Debonding Load-Bearing Capacity against Intermediate Crack-Induced Debonding Failure in FRP-Strengthened RC Beams

2011 ◽  
Vol 311-313 ◽  
pp. 1941-1944
Author(s):  
Gui Bing Li ◽  
Yu Gang Guo ◽  
Xiao Yan Sun
Keyword(s):  
Bearing Capacity ◽  
Failure Mode ◽  
Failure Modes ◽  
Rc Beams ◽  
Test Results ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Accuracy Test ◽  
New Models ◽  
Debonding Load

intermediate crack-induced debondingis one of the most dominant failure modes in FRP-strengthened RC beams. Different code models and provisions have been proposed to mitigateintermediate crack-induced debondingfailure.However, these models and provisions can not mitigate this failure mode effectively. Recnetly, new models have been proposed to solve this problem. Out of all the existing models, four typical ones are investigated in the current study. A comprehensivecomparison among these models is carried out in order to evaluate their performance and accuracy. Test results offlexural specimens with intermediate crack-induced debonding failurecollected from the existing literature are used in the current comparison. The effectivenessand accuracy of each model have been evaluated based on these experimental results. It is shown that the current modals are all conservative and inadequite to effectively mitigate intermediate crack-induced debonding in flexurally strengthened members.

Experimental Study on Seismic Behaviors of Structural Insulated Panel Shear Walls under Cyclic Loading

2011 ◽  
Vol 413 ◽  
pp. 529-534
Author(s):  
Hui Feng Yang ◽  
Wei Qing Liu ◽  
Wei Dong Lu ◽  
Shu Ai Yan
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Shear Walls ◽  
Elastic Stiffness ◽  
Width Ratio ◽  
Timber Structures ◽  
Test Results ◽  
Load Bearing Capacity ◽  
Panel Shear ◽  
Seismic Behaviors

In this paper, a total of five structural insulated panel shear walls (SIPSW), in which with plywood facing and polystyrene foam board core, were tested under low cyclic horizontal loading. For the test specimens, different wall depth-width ratio and the opening sizes have been considered. The failure modes, failure mechanics, bearing capacity, lateral stiffness and ductility are discussed in detail. The test results showed that the hysteretic curve of SIPSW shows a reversed S-shape. Also the depth-to-width ratio and the opening dimensions of the shear walls have significant effects on load bearing capacity, ductility and elastic stiffness. What’s more, the performance of the SIPSW specimens was controlled by the fastener slip behavior of the SIP-to-spline connection, especially along the bottom spline. Finally, it is indicated that SIPSW have a good satisfaction upon seismic performance when used to timber structures.

Uniaxial compression mechanical properties and damage constitutive model of limestone under osmotic pressure

2021 ◽  
pp. 105678952110454
Author(s):  
Zhanping Song ◽  
Tong Wang ◽  
Junbao Wang ◽  
Kehui Xiao ◽  
TengTian Yang
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Osmotic Pressure ◽  
Uniaxial Compression ◽  
Influencing Factor ◽  
Peak Strain ◽  
Strain Response ◽  
Test Results ◽  
Stress Strain ◽  
Compaction Factor

To study the influence of osmotic pressure on the uniaxial compression mechanical properties of limestone, uniaxial compression tests were carried out on limestone specimens under different osmotic water pressure. The test results show that with the increase of osmotic pressure, the closure strain, yield strain and peak strain of limestone gradually increase, while the closure stress, yield stress, peak stress and elastic modulus gradually decrease. To describe the stress-strain response of limestone during uniaxial compression failure, the concepts of compaction factor and osmotic pressure influencing factor were proposed, and a constitutive model of rock compaction stage was established by integrating the relationship between the compaction factor and osmotic pressure influencing factor and the tangent modulus of compaction section. On this basis, combining the continuum damage mechanics theory, and assuming that the rock micro-unit strength obeys the compound power function distribution, a constitutive model reflecting the uniaxial compression mechanical properties of rock under osmotic pressure was established by the statistical method. The rationality of the model was verified using the results of the uniaxial compression test of limestone under different osmotic pressures. The results show that the test results under different osmotic pressures are in good agreement with the theoretical curves, and the model in this paper can reflect the stress-strain response of limestone before its failure under different osmotic pressures.

Study on failure mechanism and end construction influences of double rectangular tube assembled buckling-restrained brace

2016 ◽  
Vol 20 (10) ◽  
pp. 1572-1585 ◽  
Author(s):  
Zi-qin Jiang ◽  
Yan-lin Guo ◽  
Ai-Lin Zhang ◽  
Chao Dou ◽  
Cai-Xia Zhang
Keyword(s):  
Bearing Capacity ◽  
Rational Design ◽  
Failure Modes ◽  
High Strength ◽  
Design Parameters ◽  
Local Pressure ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Buckling Restrained Brace ◽  
Rectangular Tube

The double rectangular tube assembled buckling-restrained brace is a new type of buckling energy consumption buckling-restrained brace. Because of its external restraining members, which are bound by high-strength bolts, its mechanical mechanism is more complicated and its failure modes are more varied. In this study, the double rectangular tube assembled buckling-restrained brace composition and three types of end constructions are introduced in detail. The influences of different design parameters on the performance of double rectangular tube assembled buckling-restrained brace are studied by numerical analysis methods; the possible failure modes and the influence of the end strengthening construction of double rectangular tube assembled buckling-restrained brace are also investigated, and a number of suggestions are proposed to improve this design. This study shows that the pinned double rectangular tube assembled buckling-restrained brace has four types of typical failure modes, namely, overall buckling failure, external end local pressure-bearing failure, bending failure of the extended strengthened core region and bolt threading failure. Rational design can prevent a buckling-restrained brace from losing its load-bearing capacity. In addition, compared with the end strengthening scheme with an external hoop, the end strengthening scheme with a strengthened bench can improve the load-bearing capacity of the double rectangular tube assembled buckling-restrained brace more effectively, and a reasonable design can also save materials.

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