scholarly journals Cyclic Behavior and Modeling of Bolted Glulam Joint with Cracks Loaded Parallel to Grain

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Jing Zhang ◽  
Zhi-Fang Liu ◽  
Yong Xu ◽  
Mai-Li Zhang ◽  
Liu-Cheng Mo
Keyword(s):  
Failure Modes ◽  
Damping Ratio ◽  
Three Dimensional ◽  
Material Model ◽  
Elastic Stiffness ◽  
Hysteretic Behavior ◽  
Cyclic Behavior ◽  
Equivalent Viscous Damping ◽  
Energy Dissipated ◽  
Initial Cracks

Under varying humidity and temperature conditions, with the constraint of metal fasteners to wood shrinkage, cracks along the bolt lines are generally observed in bolted glulam joints. A three-dimensional (3D) numerical model was established in software package ANSYS to investigate the cyclic behavior of bolted glulam joints with local cracks. A reversed cyclic loading was applied in the parallel-to-grain direction. The accuracy of numerical simulation was proved by comparison with full-scale experimental results. Typical failure modes were reproduced in the numerical analysis with the application of wood foundation zone material model and cohesive zone material model. The effect of crack number and length on the hysteretic behavior of bolted glulam joints was quantified by a parametric study. It was found that initial cracks impair the peak capacity and elastic stiffness of bolted glulam joints significantly. More decrease in capacity was observed in joints with more cracks, and longer cracks affect elastic stiffness more dramatically. Moreover, with the existence of initial cracks, the energy dissipated and equivalent viscous damping ratio of bolted joints are reduced by 24% and 13.3%, respectively.

scholarly journals Experimental investigations into the mechanical performance of glulam dowel-type connections with either bolts or screws as fasteners

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Zheng Li ◽  
Wei Feng ◽  
Jiajia Ou ◽  
Feng Liang ◽  
Minjuan He
Keyword(s):  
Failure Modes ◽  
Mechanical Performance ◽  
Damping Ratio ◽  
Experimental Investigations ◽  
Bolted Connections ◽  
Equivalent Viscous Damping ◽  
Moment Resisting ◽  
Loading Tests ◽  
Cyclic Loading Tests ◽  
Ductility Ratio

AbstractDowel-type connections are the most common connections in glulam structures. Bolts are often used as fasteners for dowel-type connections. However, the clearance between the bolts and the pre-drilled bolt holes leads to low rotational stiffness and insufficient moment-resisting capacity. To achieve better mechanical performance, screws can be used as alternative fasteners for dowel-type connections. In this paper, monotonic and cyclic loading tests were conducted on glulam dowel-type connections with either bolts or screws as fasteners. The failure modes, moment-resisting capacity, ductility ratio, stiffness degradation, and equivalent viscous damping ratio of the specimens were analyzed and reported. Results showed that compared with traditional bolted connections, the screwed connections had larger moment-resisting capacity and better ductility. The hysteretic loops of the screwed connections were plumper, and the pinching effect was gentler compared to those of traditional bolted connections.

scholarly journals Seismic Behavior of the Removable Links in Eccentrically Braced Frames with Semirigid Connections

2020 ◽  
Vol 2020 ◽  
pp. 1-26
Author(s):  
Qiang Shi ◽  
Shilin Yan ◽  
Xinwu Wang ◽  
Haisu Sun ◽  
Yan Zhao
Keyword(s):  
Failure Modes ◽  
Three Dimensional ◽  
Elastic Stiffness ◽  
Economic Benefits ◽  
Seismic Structure ◽  
Braced Frames ◽  
Element Analysis ◽  
Eccentrically Braced Frames ◽  
Semirigid Connections ◽  
Plate Connection

Eccentrically braced frames (EBFs) have good elastic stiffness, while semirigid joints can provide greater ductility and make all components easy to fabricate. With application of semirigid connections to EBFs, a seismic structure can be formed. After earthquake, damaged components can be easily replaced, and repair costs and maintenance time can be reduced. In order to study the seismic performance of this type of structure, four single-story plane specimens were tested under low-cycle cyclic loads. Also, a total of 7 EBF models were investigated through three-dimensional, nonlinear finite element analysis. Good agreement is achieved between the simulation and experimental results. The results show that the failure modes of the EBFs with semirigid connections are the fracture at link end plate connection, and no obvious buckling deformation and cracks occur in the other components. The EBFs with semirigid connections exhibit good inelastic rotation ability, and the inelastic rotation of all specimens and models exceeds the limit of 2016 AISC specification. Due to the slip between members, the hysteretic curves of those new structures show different degrees of pinching phenomenon and it becomes more obvious with the increase of the length of links. By analyzing the strain of the bolts, it is found that the bolt strains of the joints of link-to-beam are the highest, while the bolt strains of the joints of beam-to-column and column-to-brace are smaller. This structure system shows higher energy dissipation capacity and good economic benefits.

Seismic Performance of Prestressed Reinforced Concrete Piles Reinforced with Nonprestressed Reinforcements

2013 ◽  
Vol 438-439 ◽  
pp. 1466-1470
Author(s):  
Tie Cheng Wang ◽  
Wen Jin Wang ◽  
Hai Long Zhao ◽  
Zhi Jian Yang
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Failure Modes ◽  
High Strength ◽  
Hysteretic Behavior ◽  
Equivalent Viscous Damping ◽  
Concrete Piles ◽  
Hysteretic Performance ◽  
Cycle Loading ◽  
Energy Absorbing

The main purpose of this paper is to study the seismic performance of prestressed reinforced concrete pile (PRC pile) reinforced with nonprestressed reinforcements. Two prestressed high strength concrete piles (PHC piles) and two PRC piles were tested. The variables studied in this research are the prestressed reinforcements ratio and nonprestressed reinforcements ratio. The piles subjected to low-cycle loading were presented in this paper, including the hysteretic performance, stiffness degradation curves, coefficient of equivalent viscous damping and skeleton-frame curves. It is shown that the failure modes of all specimens are bending damage from the test and PRC piles have good energy-absorbing hysteretic behavior.

Numerical Modeling of the Failure of Magnesium Tubes Under Compressive Loading

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Jonathan Rossiter ◽  
Kaan Inal ◽  
Raja Mishra
Keyword(s):  
Wall Thickness ◽  
Failure Criterion ◽  
Failure Modes ◽  
Compressive Loading ◽  
Three Dimensional ◽  
Material Model ◽  
Fe Model ◽  
Macroscopic Strain ◽  
Compression Tests ◽  
Stress Concentrations

A new finite element (FE) specific failure criterion utilizing hardening rates to quantify bending stress is implemented into the MAT_124 material model in the commercial software LS-DYNA to simulate fracture of extruded AZ31 and cast AM60 magnesium alloy tubes. The simulations are performed by requiring element erosion of hexahedral solid elements in a three-dimensional (3D) FE model when the failure criterion is satisfied at any point in the simulation. Experimental stress–strain curves from tensile and compression tests of the materials are used as inputs in the model. The simulations reproduce the measured load displacement data as well as general features of the experimental failure modes of round and rectangular tubes undergoing axial crush tests. The model is applied to investigate the effects of a variety of design features, such as varying tube wall thickness, preformed bulges, alternate bands of Al and Mg alloys, and cladding Al on magnesium, on the macroscopic strain to failure. The results show that adding multiple preformed bulges to the tubes can increase the strain to failure and reduce the force required to cause deformation. Adding a single bulge concentrates the strain causing reduced macroscopic strain to failure. Placing sections of reduced wall thickness or brazing in sections of aluminum causes stress concentrations which reduce the macroscopic strain to failure. Cladding aluminum onto the outside of the magnesium tube is shown to improve strain to failure.

Calibration of a three-dimensional multimechanism shape memory alloy material model for the prediction of the cyclic “attraction” character in binary NiTi alloys

2012 ◽  
Vol 24 (1) ◽  
pp. 70-88 ◽  
Author(s):  
Atef F Saleeb ◽  
Binod Dhakal ◽  
Santo A Padula ◽  
Darrell J Gaydosh
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Three Dimensional ◽  
Material Model ◽  
Cyclic Behavior ◽  
Modeling Framework ◽  
Tension Tests ◽  
High Transformation ◽  
Behavior Characteristics

As typically utilized in applications, a particular shape memory alloy device or component operates under a large number of thermomechanical cycles, hence, the importance of accounting for the cyclic behavior characteristics in modeling and characterization of these systems. To this end, the present work is focused on the characterization of the evolutionary, cyclic behavior of binary 55NiTi (having a moderately-high transformation temperature range). In this study, an extensive set of test data from recent cyclic, isobaric, tension tests was used. Furthermore, for the calibration and characterization of this material, a newly developed, multiaxial, material-modeling framework was implemented. In this framework, multiple, inelastic mechanisms are used to regulate the partitioning of energy dissipation and storage governing the evolutionary thermomechanical response.

scholarly journals Equivalent Viscous Damping Ratio Model for Flexure Critical Reinforced Concrete Columns

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Qin Zhang ◽  
Zong-yan Wei ◽  
Jin-xin Gong ◽  
Ping Yu ◽  
Yan-qing Zhang
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Damping Ratio ◽  
Hysteretic Behavior ◽  
Viscous Damping ◽  
Ratio Model ◽  
Rc Columns ◽  
Equivalent Viscous Damping ◽  
Rc Structures ◽  
Energy Dissipation Capacity

In order to determine the energy dissipation capacity of flexure critical reinforced concrete (RC) columns reasonably, an expression for describing the hysteretic behavior including loading and unloading characteristics of flexure critical RC columns is presented, and then, a new equivalent viscous damping (EVD) ratio model including its simplified format, which is interpreted as a function of a displacement ductility factor and a ratio of secant stiffness to yield stiffness of columns, is developed based on the proposed hysteretic loop expression and experimental data from the PEER column database. To illustrate the application of the proposed equivalent damping ratio model, a case study of pushover analysis on a flexure critical RC bridge with a single-column pier is provided. The analytical results are also compared with the results obtained by other models, which indicate that the proposed model is more general and rational in predicting energy dissipation capacity of flexure critical RC structures subjected to earthquake excitations.

scholarly journals Cyclic Behavior of Steel Beam to CFT Column Connections with Gusset Plates

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Peng Wang ◽  
Zhan Wang ◽  
Jianrong Pan ◽  
Yanjun Zheng ◽  
Deming Liu
Keyword(s):  
Failure Modes ◽  
Plastic Hinge ◽  
Hysteretic Behavior ◽  
Cyclic Behavior ◽  
Element Analysis ◽  
Gusset Plates ◽  
Numerical Studies ◽  
Story Drift ◽  
Risk Areas ◽  
Cft Column

Beam-brace-CFT (concrete-filled tubular) column connections provide excellent performance in resisting seismic loads in high-risk areas. However, the load transmission mechanism of this type of connection still remains unclear, and there is a lack of study on it. Therefore, in this paper, the mechanical behavior of beam-brace-CFT column (BBC) connections penetrated by gusset plates was evaluated through experiments and finite element analysis to resolve this issue. The failure modes, strength, stiffness, ductility, and energy dissipation of this type of connection were studied. Experiment results indicated that the gusset plates in BBC (beam-brace-CFT) connections could effectively move the plastic hinge on beam away from the column face, reduce the strain concentration between the beam end and column face, and notably improve the hysteretic behavior; the plastic rotation was able to achieve at least 4% story drift angle before 20% strength degradation. Numerical studies were carried out and validated by experiment results, and then the influence of the weld length and strengthening methods were investigated; some improvement of design suggestions was proposed.

Experimental Research on Out-of-Plane Cyclic Behavior of Steel-Plate Composite Walls

2016 ◽  
Vol 10 (01) ◽  
pp. 1650001 ◽  
Author(s):  
Yue Yang ◽  
Jingbo Liu ◽  
Xin Nie ◽  
Jiansheng Fan
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Steel Plate ◽  
Plate Thickness ◽  
Steel Plates ◽  
Hysteretic Behavior ◽  
Cyclic Behavior ◽  
Shear Span ◽  
Out Of Plane ◽  
Composite Walls

Three steel-plate composite walls were tested under reversal loads. The primary purpose of this experiment was to investigate the out-of-plane behavior of steel-plate composite walls under seismic actions, including the failure modes, hysteretic behavior, strength, and stiffness while emphasizing the effects of shear span, connection details, and thickness of the steel plates. All specimens showed some pinching effect in the hysteresis loops. Both shear failure and flexural failure occurred in the tests depending on the shear span and steel plate thickness of the specimens. All surface steel plates of the specimens remained unbuckled before yielding during the loading process, which indicated that the ratio of connector spacing to surface steel plate thickness adopted for the specimens satisfied the requirement of yielding before buckling. The test results also showed that the tie bars contributed significantly to the out-of-plane shear strength of the steel-plate composite walls.

scholarly journals Experimental Study of Hysteretic Steel Damper for Energy Dissipation Capacity

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Daniel R. Teruna ◽  
Taksiah A. Majid ◽  
Bambang Budiono
Keyword(s):  
Energy Dissipation ◽  
Damping Ratio ◽  
Elastic Stiffness ◽  
Absorption Capacity ◽  
Hysteretic Behavior ◽  
Hysteretic Model ◽  
Skeleton Curve ◽  
Ductility Factor ◽  
Steel Damper ◽  
Cumulative Plastic Strain

This study aims to evaluate energy absorption capacity of hysteretic steel damper for earthquake protection of structures. These types of steel dampers are fabricated from mild steel plate with different geometrical shapes on the side part, namely, straight, concave, and convex shapes. The performance of the proposed device was verified experimentally by a series of tests under increasing in-plane cyclic load. The overall test results indicated that the proposed steel dampers have similar hysteretic curves, but the specimen with convex-shaped side not only showed stable hysteretic behavior but also showed excellent energy dissipation capabilities and ductility factor. Furthermore, the load-deformation relation of these steel dampers can be decomposed into three parts, namely, skeleton curve, Bauschinger part, and elastic unloading part. The skeleton curve is commonly used to obtain the main parameters, which describe the behavior of steel damper, namely, yield strength, elastic stiffness, and postyield stiffness ratio. Moreover, the effective stiffness, effective damping ratio, cumulative plastic strain energy, and cumulative ductility factor were also derived from the results. Finally, an approximation trilinear hysteretic model was developed based on skeleton curve obtained from experimental results.

Scanning Electron Microscopy in Hybrid Microelectronics

1976 ◽  
Vol 34 ◽  
pp. 456-457
Author(s):  
S. Khadpe ◽  
R. Faryniak
Keyword(s):  
Integrated Circuits ◽  
Thick Film ◽  
Integrated Circuit ◽  
Failure Modes ◽  
Three Dimensional ◽  
Circuit Components ◽  
Hybrid Microcircuit ◽  
Electrical Connections ◽  
Scanning Electron

The Scanning Electron Microscope (SEM) is an important tool in Thick Film Hybrid Microcircuits Manufacturing because of its large depth of focus and three dimensional capability. This paper discusses some of the important areas in which the SEM is used to monitor process control and component failure modes during the various stages of manufacture of a typical hybrid microcircuit.Figure 1 shows a thick film hybrid microcircuit used in a Motorola Paging Receiver. The circuit consists of thick film resistors and conductors screened and fired on a ceramic (aluminum oxide) substrate. Two integrated circuit dice are bonded to the conductors by means of conductive epoxy and electrical connections from each integrated circuit to the substrate are made by ultrasonically bonding 1 mil aluminum wires from the die pads to appropriate conductor pads on the substrate. In addition to the integrated circuits and the resistors, the circuit includes seven chip capacitors soldered onto the substrate. Some of the important considerations involved in the selection and reliability aspects of the hybrid circuit components are: (a) the quality of the substrate; (b) the surface structure of the thick film conductors; (c) the metallization characteristics of the integrated circuit; and (d) the quality of the wire bond interconnections.

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