scholarly journals Behavior of GFRP-Wood Composite Sandwich Beam-Column Joints with Angle Steels

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
ZhiJin Xie ◽  
YuJun Qi ◽  
Hai Fang ◽  
WeiQing Liu
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Sandwich Beam ◽  
Tensile Failure ◽  
Wood Composite ◽  
Initial Stiffness ◽  
Composite Sandwich ◽  
Glass Fiber Reinforced ◽  
Connection System ◽  
System Configurations

In this paper, a new type of connection system was proposed for joints between GFRP-wood composite sandwich beams and columns which were made of glass fiber-reinforced polymer (GFRP) face sheets and southern pine wood cores. The connection system comprised steel angles anchored to the column, and the beam was bolted to the angles. Six different connection system configurations were tested to understand the static behavior of the connection system under different parameters including the length of the beam-closed limb and the presence of ribs. The failure modes of the connection system obtained in tests were of three types: yield failure of the angle steels, local crushing failure of the GFRP-wood composite sandwich beam, and tensile failure of the bolt on the beam-closed limb. The initial rotational stiffness values of the three specimens with ribs were 113.75%, 119.56%, and 227.94% higher than the corresponding three specimens without ribs. And the ductility of connection improved by up to 30.28% due to the presence of stiffener ribs. Based on the tests, the bearing capacity and stiffness of the connection system were predicted. For the specimens without ribs, the method in Eurocode 3 was adopted for bearing capacity and stiffness predictions. For the specimens with ribs, a mechanical model was established for bearing capacity and initial stiffness predictions, which was solved according to the corresponding stress features and failure modes. The analytical results were in good agreement with the experimental results.

scholarly journals Research on Failure Characteristics of Concrete Three-Point Bending Beams with Preexisting Cracks in Different Positions Based on Numerical Simulation

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Liuqun Zhao ◽  
Li Zheng ◽  
Hui Qin ◽  
Tiesuo Geng ◽  
Yonggang Tan ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Failure Process ◽  
Engineering Application ◽  
Tensile Failure ◽  
Engineering Structures ◽  
Failure Characteristics ◽  
Three Point Bending ◽  
Wide Range

Concrete three-point bending beams with preexisting cracks are widely used to study the growth process of I-II mixed mode cracks. Studying the failure characteristics of preexisting cracks at different locations on concrete three-point bending beams not only has important scientific significance but also has a wide range of engineering application backgrounds in the safety assessment of engineering structures. In this paper, through several numerical experiments, the influence of preexisting cracks at different positions on the failure characteristics of concrete three-point bending beams is studied, and three typical failure modes are obtained. The failure process of the specimens with three typical failure modes is discussed in detail, and it is pointed out that the crack failure mode is tensile failure. The change trends of bearing capacity, acoustic emission quantity, and acoustic emission energy of three typical failure modes are analyzed. The maximum bearing capacity, the maximum acoustic emission quantity, and energy of three failure modes of concrete three-point bending beams generally show an increasing trend.

scholarly journals Mechanical Behavior of Sandwich Panels with Hybrid PU Foam Core

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Xudong Zhao ◽  
Li Tan ◽  
Fubin Zhang
Keyword(s):  
Failure Modes ◽  
Peak Load ◽  
Hard Core ◽  
Experimental Results ◽  
Control Panel ◽  
Foam Core ◽  
Initial Stiffness ◽  
Composite Sandwich ◽  
Pu Foam ◽  
Compression Area

The traditional composite sandwich structures have disadvantages of low shear modulus and large deformation when used in civil engineering applications. To overcome these problems, this paper proposed a novel composite sandwich panel with upper and lower GFRP skins and a hybrid polyurethane (PU) foam core (GHP panels). The hybrid core is composed of different densities (150, 250, and 350 kg/m3) of the foam core which is divided functionally by horizontal GFRP ribs. The hard core is placed in the compression area to resist compressive strength and improve the stiffness of the composite sandwich structure, while the soft core is placed in the tension area. Six GHP panels were tested loaded in 4-point bending to study the effect of horizontal ribs and hybrid core configurations on the stiffness, strength, and failure modes of GHP panels. Experimental results show that compared to the control panel, a maximum of 54.6% and 50% increase in the strength and bending stiffness can be achieved, respectively. GHP panels with the hybrid PU foam core show obvious secondary stiffness. Finally, analytical methods were proposed to predict the initial stiffness and peak load of the GHP panels, and the results agree well with experimental results.

scholarly journals Experimental Study on Hysteretic Behavior of the Overlapped K-Joints with Concrete Filled in Chord

2019 ◽  
Vol 9 (7) ◽  
pp. 1456 ◽  
Author(s):  
Wenwei Yang ◽  
Ruhao Yan ◽  
Yaqi Suo ◽  
Guoqing Zhang ◽  
Bo Huang
Keyword(s):  
Plastic Deformation ◽  
Energy Dissipation ◽  
Cyclic Loading ◽  
Bearing Capacity ◽  
Failure Modes ◽  
The United States ◽  
Hysteretic Behavior ◽  
Tensile Failure ◽  
Element Analysis ◽  
Better Than

Due to the insufficient radial stiffness of the steel tube, the cracking of the weld and the plastic deformation of the string often occur under the cyclic loading of the hollow section pipe joint. In order to avoid such a failure, the overlapped K-joints were strengthened by pouring different concrete into the chords. Furthermore, to explore the detailed effect of filling different concrete in a chord on the hysteretic behavior of the overlapped K-joints, six full-scale specimens were fabricated by two forms, which included the circular chord and braces, the square chord and circular braces, and the low cyclic loading tests, which were carried out. The failure modes, hysteretic curves and skeleton curves of the joints were obtained, and the bearing capacity, ductility and energy dissipation of the joints were evaluated quantitatively. The results showed that plastic failure occurs on the surface of the chord of the joints without filling concrete, while the failure mode of the joints filled with concrete in the chords was the tensile failure of the chords at the weld of the brace toe, and the compressive braces had a certain buckling deformation; The strengthening measures of concrete filled with chord can effectively improve the mechanical properties of the K-joints, the delay of the plastic deformation of the chord, and improve the bearing capacity of the K-joints. Contrarily, the ductility coefficient and the energy dissipation ratio of K-joints decreased with the concrete filled in the chord. The hysteretic behavior of the K-joints with a circular chord and brace was slightly better than that of the K-joints with a square chord and circular brace, and the hysteretic behavior of the K-joints strengthened with fly ash concrete, which was better than that of the K-joints strengthened with ordinary concrete. The results of ANSYS (a large general finite element analysis software developed by ANSYS Company in the United States) analysis agreed well with the experimental results.

Characterization of Wood-Polypropylene Composite Sandwich System

2000 ◽  
Vol 34 (18) ◽  
pp. 1582-1599 ◽  
Author(s):  
Ganesan Kumar ◽  
Karthik Ramani
Keyword(s):  
Mechanical Analysis ◽  
Environmental Scanning ◽  
Normal Wood ◽  
Scanning Electron Micrographs ◽  
Wood Composite ◽  
Polypropylene Composite ◽  
Moisture Condition ◽  
Composite Sandwich ◽  
Glass Fiber Reinforced ◽  
End Use

A new wood-polypropylene composite sandwich was made by bonding unidirectional continuous glass fiber reinforced polypropylene (UCGPP) composite to oak wood using a thermoplastic tie layer. In order to evaluate the practical utility of wood-composite sandwich systems, the effects of moisture changes in both continuous and cyclic manner were investigated by monitoring the modulus change. Dynamic mechanical analysis (DMA) of neat wood and wood-composite sandwich was carried out under controlled relative humidity (RH) and isothermal conditions to simulate moisture desorption/sorption processes. It is observed that under continuous desorption condition the modulus increase is less in the case of wood-sandwich (20%) when compared with neat wood (35%). However, under desorption/sorption cycle conditions the wood-sandwich undergoes significant modulus change when compared with neat wood. It is inferred that while bonding wood with UCGPP composite helps reduce the variation in modulus under continuous desorption, it is not the case under cyclic moisture condition. The modulus behavior of both dry and normal wood-sandwiches at different end-use temperatures is also studied using DMA. Optical and environmental scanning electron micrographs show the distribution and penetration pattern of tie layer into wood as well as UCGPP composite, thus demonstrating the significance of micro-mechanical interlocking for bonding.

Experimental Investigations of Masonry Columns Strengthened by SGFRP under Eccentric Loads

2013 ◽  
Vol 351-352 ◽  
pp. 1509-1513
Author(s):  
Zhi Zhang ◽  
Qian Gu ◽  
Qi Ming Yu
Keyword(s):  
Bearing Capacity ◽  
Glass Fiber ◽  
Seismic Behavior ◽  
Failure Modes ◽  
Fiber Reinforced Polymer ◽  
Experimental Investigations ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced

5 masonry columns were strengthened by Sprayed Glass Fiber Reinforced Polymer (SGFRP) in this paper, and a research of the seismic behavior of them tested by eccentric loading experiment was presented. The failure modes of the strengthened masonry columns were illustrated and strengthening effects of them were discussed. The results showed that the bearing capacity of the reinforced columns increased greatly, and the ductility of them also improved significantly. Comparing the strengthening effects of the columns when the thickness of SGFRP and the number of glass fiber are different, some reasonable reinforce suggestions are proposed.

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.

Cyclic Behavior of Precast Segmental UHPFRC Bridge Columns with Replaceable Damage-Concentrated Elements

2018 ◽  
Author(s):  
Zhen Wang ◽  
Jingquan Wang ◽  
Junzheng Zhu
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Inner Core ◽  
Fiber Reinforced Concrete ◽  
Cyclic Behavior ◽  
Deformation Capacity ◽  
Initial Stiffness ◽  
River Sand ◽  
Rapid Repair ◽  
Bridge Column

<p>A novel precast segmental bridge column was put forward innovatively to contribute to accelerated bridge construction and rapid repair of bridge after earthquake, which is in accordance with the theme called engineering innovations for rapid urbanisation. The proposed bridge column was manufactured with cost-effective ultrahigh performance fiber-reinforced concrete (UHPFRC) incorporating river sand and coarse aggregate. As the potential damaged region, the bottom segment was composed of three parts: inner core zone designed to bear axial loading, outer replaceable UHPFRC plates (RUP) designed to bear lateral loading, and middle replaceable steel dissipaters (RSD) designed to enhance energy dissipation (ED), when the entire bridge structure was subjected to earthquake shock. The rapid repair after earthquake was completed with substitutions of replaceable damage-concentrated elements including RUP and RSD. Cyclic loading tests were conducted on three 1:3 scaled specimens and their repaired specimens. The research parameters included posttensioning (PT) force level and usage of RSD. Test results show that both construction and repair can be very time-saving for the proposed bridge column. Major damage focuses on replaceable damage-concentrated elements while remaining parts are basically intact. All the specimens present good deformation capacity and excellent self-centering feature. Two different failure modes can be found: some specimens failed in the lateral bearing capacity while others failed in the ED capacity. Compared with the original specimen failed in the same failure mode, the repaired specimen has similar lateral bearing capacity and deformation capacity but seriously weakened initial stiffness.</p>

Experimental study on double-headed screw joints and their application in bamboo shear walls

2020 ◽  
pp. 136943322097177
Author(s):  
Qingfang Lv ◽  
Yi Ding ◽  
Ye Liu
Keyword(s):  
Energy Dissipation ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Shear Failure ◽  
Single Layer ◽  
Shear Walls ◽  
Shear Wall ◽  
Tensile Failure ◽  
Step Test ◽  
Double Shear

Due to the weak withdrawal capacities of conventional nail joints, using double-headed screw joints as reliable connections in bamboo structures is investigated for the first time. A two-step test program is presented in this paper. In the first step, a double shear test is carried out to investigate the influences of the end distance and bamboo grain direction on the performance of double-headed screw joints. The test shows that there are four main failure modes of double-headed screw joints: double-headed screw shear failure, bearing failure of the hole wall, tensile failure of the bamboo cover panel and shear failure of the cover panel end. In the second step of test, the proposed double-headed screw joints are applied to three single-layer single-span bamboo shear walls, and low-cycle reversed loading tests are applied to the walls with double-headed screw spacings of 50 mm, 100 mm and 150 mm. The failure mode, hysteretic behaviour and energy dissipation performance of the shear walls are discussed. Test results show that the two main failure modes of the bamboo shear walls are the tensile failure of the edge of the wall and shear failure of the double-headed screws. Among the different spacings, the bearing capacity and effective stiffness of the wall with a double-headed screw spacing of 50 mm are the largest, the ductility and energy dissipation capacity of the bamboo shear wall with a double-headed screw spacing of 100 mm are the largest, and the bearing capacity and ductility of the bamboo shear wall with a double-headed screw spacing of 150 mm are the worst.

Bending Response of Composite Sandwich Beams with M-Type Folded Cores

2014 ◽  
Vol 1049-1050 ◽  
pp. 452-455
Author(s):  
Li Xin Cong ◽  
Yu Guo Sun
Keyword(s):  
Failure Modes ◽  
Fiber Composite ◽  
Sandwich Beam ◽  
Deformation Mode ◽  
Sandwich Beams ◽  
The Finite Element Method ◽  
Carbon Fiber Composite ◽  
Maximum Displacement ◽  
Three Point Bending ◽  
Composite Sandwich

Bending properties and failure modes of sandwich structure with carbon fiber composite M-type folded cores were investigated and presented in this paper. Three point bending responses of both sandwich beams were measured. The finite element method was utilized to determine deformation mode of sandwich beam with M-type folded cores. Cores buckling and debonding have been studied under three point bending and the maximum displacement was also studied using FE-analytical and experimental methods.

scholarly journals Study of Seismic Behavior of RC Beam-Column Joints Strengthened by Sprayed FRP

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Zhao Yang ◽  
Yong Liu ◽  
Jiajia Li
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Compression Ratio ◽  
Seismic Behavior ◽  
Failure Modes ◽  
Rc Beam ◽  
Initial Stiffness ◽  
Axial Compression Ratio ◽  
Energy Dissipation Capacity ◽  
Strength And Stiffness

To study the seismic behavior of RC beam-column joints strengthened with sprayed FRP, five 1 : 2 reduced-scale specimens of joints were tested through quasi-static experiments. The failure modes, hysteretic curves, skeleton curves, strength, deformation, degradation of strength and stiffness, ductility, and energy dissipation capacity were studied. Furthermore, the effect of three main influencing factors including the sprayed FRP thickness, strengthened area, and axial compression ratio was analyzed in this paper as well. The results show that sprayed FRP strengthening can improve the seismic behavior of RC beam-column joints effectively. The increase of sprayed FRP thickness can lead to a better seismic performance for the joints. Strengthening area can affect the bearing capacity obviously. Higher axial compression ratio can increase the bearing capacity and initial stiffness, but it can make the deformation capacity and ductility decreased. The study can provide references to further research on the sprayed FRP material for strengthening of RC beam-column joints.

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