Behavior of Glued Connections under Shear Loading

2015 ◽  
Vol 662 ◽  
pp. 241-244
Author(s):  
Klára Machalická ◽  
Martina Eliášová
Keyword(s):  
Failure Modes ◽  
Numerical Models ◽  
Substrate Surface ◽  
Adhesive Layer ◽  
Life Time ◽  
Shear Loading ◽  
Load Bearing ◽  
Shear Connection ◽  
Shear Loads

An intensive research in load-bearing glass structures leads to the requirement for performing glass-to-glass or glass-to-different material connections. Glued shear connection is suitable for these applications mainly due to its uniform stress distribution in larger area in comparison with bolted connections. The reliability of adhesive in the connection during the life time of a structure is affected by many factors, [1], [2], [3], [4]. The article deals with the experimental analysis focused on the determination of material characteristics of adhesives in planar connections, it describes the effect of various factors on the behavior of an adhesive joint under increasing shear loads, its ultimate load-bearing capacity and its failure modes. The main investigated factors are the type of adhesive, the type of connected materials (material of substrate), surface treatment and the thickness of the adhesive layer. Due to importance of adhesive layer thickness especially in rigid and semi-rigid glues, numerical models responding to the effect of thickness was carried out.

scholarly journals Numerical Investigations on Non-Rectangular Anchor Groups under Shear Loads Applied Perpendicular or Parallel to an Edge

CivilEng ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 692-711
Author(s):  
Boglárka Bokor ◽  
Akanshu Sharma
Keyword(s):  
Failure Modes ◽  
Failure Load ◽  
Shear Loading ◽  
Constitutive Law ◽  
Kinematic Constraint ◽  
Microplane Model ◽  
Numerical Investigations ◽  
Shear Loads ◽  
Current Design ◽  
Rectangular Configuration

Anchorages of non-rectangular configuration, though not covered by current design codes, are often used in practice due to functional or architectural needs. Frequently, such anchor groups are placed close to a concrete edge and are subjected to shear loads. The design of such anchorages requires engineering judgement and no clear rules are given in the codes and standards. In this work, numerical investigations using a nonlinear 3D FE analysis code are carried out on anchor groups with triangular and hexagonal anchor patterns to understand their behavior under shear loads. A microplane model with relaxed kinematic constraint is utilized as the constitutive law for concrete. Two different orientations are considered for both triangular and hexagonal anchor groups while no hole clearance is considered in the analysis. Two loading scenarios are investigated: (i) shear loading applied perpendicular and towards the edge; and (ii) shear loading applied parallel to the edge. The results of the analyses are evaluated in terms of the load-displacement behavior and failure modes. A comparison is made between the results of the numerical simulations and the analytical calculations according to the current approaches. It is found that, similar to the rectangular anchorages, and also for such non-rectangular anchorages without hole clearance, it may be reasonable to calculate the concrete edge breakout capacity by assuming a failure crack from the back anchor row. Furthermore, the failure load of the investigated groups loaded in shear parallel to the edge may be considered as twice the failure load of the corresponding groups loaded in shear perpendicular to the edge.

scholarly journals Use of bolted shear connectors in composite construction

2018 ◽  
Author(s):  
Xianghe Dai ◽  
Dennis Lam ◽  
Therese Sheehan ◽  
Jie Yang ◽  
Kan Zhou
Keyword(s):  
Numerical Simulation ◽  
Composite Beam ◽  
Failure Modes ◽  
Numerical Models ◽  
High Strength ◽  
Shear Behaviour ◽  
Composite Construction ◽  
Structural Behaviour ◽  
Shear Connectors ◽  
Shear Connection

Composite beam incorporated steel profiled decking has been extensively used for multi-storey buildings and is now one of the most efficient and economic form of flooring systems. However, the current composite flooring system is not demountable and would require extensive cutting on site during demolition, and the opportunity to reuse the steel components is lost even though these components could be salvaged and recycled. This paper presents the use of high strength bolts as shear connectors in composite construction, the shear behaviour and failure modes were observed and analysed through a series of push-off tests and numerical simulation. The results highlighted the structural behaviour of three different demountable shear connection forms in which continuous slabs or un-continuous slabs were used. Numerical models were validated against experimental observation. Both experimental and numerical results support the high strength bolts used as demountable shear connectors and lead to a better understanding to the behaviour of this form of shear connectors.

scholarly journals Test Method Development and Determination of Three-Dimensional Strength and Failure Modes of Polyvinyl Chloride Structural Foams

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Akira Miyase ◽  
Su Su Wang
Keyword(s):  
Polyvinyl Chloride ◽  
Failure Modes ◽  
Test Methods ◽  
Shear Loading ◽  
Test Method ◽  
Damage And Failure ◽  
Out Of Plane ◽  
Loading Modes ◽  
Structural Foams

A comprehensive study has been conducted to develop proper test methods for accurate determination of failure strengths along different material directions of closed-cell polymer-based structural foams under different loading modes. The test methods developed are used to evaluate strengths and failure modes of commonly used H80 polyvinyl chloride (PVC) foam. The foam's out-of-plane anisotropic and in-plane isotropic cell microstructures are considered in the test methodology development. The effect of test specimen geometry on compressive deformation and failure properties is addressed, especially the aspect ratio of the specimen gauge section. Foam nonlinear constitutive relationships, strength and failure modes along both in-plane and out-of-plane (rise) directions are obtained in different loading modes. Experimental results reveal strong transversely isotropic characteristics of foam microstructure and strength properties. Compressive damage initiation and progression prior to failure are investigated in an incremental loading–unloading experiment. To evaluate foam in-plane and out-of-plane shear strengths, a scaled shear test method is also developed. Shear loading and unloading experiments are carried out to identify the causes of observed large shear damage and failure modes. The complex damage and failure modes in H80 PVC foam under different loading modes are examined, both macroscopically and microscopically.

Feasibility of Molecular Structure Determination With a High Resolution Electron Microscope

1968 ◽  
Vol 26 ◽  
pp. 338-339
Author(s):  
T. A. Welton
Keyword(s):  
Electron Microscope ◽  
Substrate Surface ◽  
Helical Axis ◽  
Base Plane ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
High Degree ◽  
Degree Of Order ◽  
Purine Pyrimidine

An ultimate design goal for an improved electron microscope, aimed at biological applications, is the determination of the structure of complex bio-molecules. As a prototype of this class of problems, we propose to examine the possibility of reading DNA sequence by an imaginable instrument design. This problem ideally combines absolute importance and relative simplicity, in as much as the problem of enzyme structure seems to be a much more difficult one.The proposed technique involves the deposition on a thin graphite lamina of intact double helical DNA rods. If the structure can be maintained under vacuum conditions, we can then make use of the high degree of order to greatly reduce the work involved in discriminating between the four possible purine-pyrimidine arrangements in each base plane. The phosphorus atoms of the back bone form in projection (the helical axis being necessarily parallel to the substrate surface) two intertwined sinusoids. If these phosphorus atoms have been located up to a certain point on the molecule, we have available excellent information on the orientation of the base plane at that point, and can then locate in projection the key atoms for discrimination of the four alternatives.

Determination of cerebral glucose transport and metabolic kinetics by dynamic MR spectroscopy

1997 ◽  
Vol 273 (6) ◽  
pp. E1216-E1227 ◽  
Author(s):  
P. C. M. Van Zijl ◽  
D. Davis ◽  
S. M. Eleff ◽  
C. T. W. Moonen ◽  
R. J. Parker ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Kinetic Equations ◽  
Direct Determination ◽  
Life Time ◽  
Compartment Model ◽  
Brain Extract ◽  
Influx Rate ◽  
Positron Emission

A new in vivo nuclear magnetic resonance (NMR) spectroscopy method is introduced that dynamically measures cerebral utilization of magnetically labeled [1-13C]glucose from the change in total brain glucose signals on infusion. Kinetic equations are derived using a four-compartment model incorporating glucose transport and phosphorylation. Brain extract data show that the glucose 6-phosphate concentration is negligible relative to glucose, simplifying the kinetics to three compartments and allowing direct determination of the glucose-utilization half-life time [ t ½ = ln2/( k 2 + k 3)] from the time dependence of the NMR signal. Results on isofluorane ( n = 5)- and halothane ( n = 7)- anesthetized cats give a hyperglycemic t ½ = 5.10 ± 0.11 min−1 (SE). Using Michaelis-Menten kinetics and an assumed half-saturation constant Kt = 5 ± 1 mM, we determined a maximal transport rate T max = 0.83 ± 0.19 μmol ⋅ g−1 ⋅ min−1, a cerebral metabolic rate of glucose CMRGlc = 0.22 ± 0.03 μmol ⋅ g−1 ⋅ min−1, and a normoglycemic cerebral influx rate CIRGlc = 0.37 ± 0.05 μmol ⋅ g−1 ⋅ min−1. Possible extension of this approach to positron emission tomography and proton NMR is discussed.

An Experimental Determination of a Real Fire Performance of a Non-Load Bearing Glass Wall Assembly

2006 ◽  
Vol 43 (1) ◽  
pp. 77-89 ◽  
Author(s):  
Samuel L. Manzello ◽  
Richard G. Gann ◽  
Scott R. Kukuck ◽  
Kuldeep R. Prasad ◽  
Walter W. Jones
Keyword(s):  
Experimental Determination ◽  
Fire Performance ◽  
Glass Wall ◽  
Load Bearing ◽  
Wall Assembly

In situ ATR - FTIR spectroscopy of Hf(IV) tert butoxide adsorption on Si and Ge

2006 ◽  
Vol 917 ◽  
Author(s):  
Shilpa Dubey ◽  
Keijing Li ◽  
Harish Bhandari ◽  
Zheng Hu ◽  
C. Heath Turner ◽  
...  
Keyword(s):  
Hafnium Oxide ◽  
Density Functional ◽  
Substrate Surface ◽  
Surface Concentration ◽  
Bidentate Ligand ◽  
Initial Reaction ◽  
Process Conditions ◽  
Reaction Cell

AbstractHafnium oxide ultra thin films on Si (100) are being developed to replace thermally grown SiO2 gates in CMOS devices. In this work, a specially designed Attenuated Total Reflectance - Fourier Transform Infra Red Spectroscopy (ATR-FTIR) reaction cell has been developed to observe chemisorption of hafnium (IV) t-butoxide onto a Si and Ge ATR crystal heated up to 250°C and under 1 torr of vacuum to observe the initial reaction pathways and species on the substrate surface in real time and under typical process conditions. Chemisorption spectra were compared to spectra of the liquid precursor and to spectra generated by density functional theory (DFT) calculations of liquid, monodentate and bidentate absorbed precursor. An asymmetric stretching mode located at ~1017 cm-1 present in the chemisorbed spectra but not in the liquid spectra indicates that the adsorbed hafnium containing group is prevalent as a bidentate ligand according to calculations. Surface concentration of the chemisorbed species was dependant on the substrate temperature and precursor partial pressure allowing for determination of heats of adsorption which was 26.5 kJ/mol on Si.

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