scholarly journals Glass FRP-Reinforced Geopolymer Based Columns Comprising Hybrid Fibres: Testing and FEA Modelling

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 324
Author(s):  
Ahmad Rashedi ◽  
Riadh Marzouki ◽  
Ali Raza ◽  
Khawar Ali ◽  
Niyi Gideon Olaiya ◽  
...  

This study seeks to evaluate the effectiveness of glass-FRP-reinforced geopolymer concrete columns integrating hybrid fibres (GFGC columns) and steel bar-reinforced geopolymer concrete columns incorporating hybrid fibres (SFGC columns) under eccentric and concentric loadings. Steel fibre (SF) and polypropylene fibres (PF) are two types of fibres that are mixed into hybrid fibre-reinforced geopolymer concrete (HFRGC). Eighteen circular concrete columns with a cross-section of 300 mm × 1200 mm were cast and examined under axial loading up to failure. Nine columns were cast with glass-FRP rebars, whereas the other nine were cast with steel rebars. Using ABAQUS, a nonlinear finite element model was established for the GFGC and SFGC columns. The HFRGC material was modelled using a simplified concrete damage plasticity model, whereas the glass-FRP material was simulated as a linear elastic material. It was observed that GFGC columns had up to 20% lower axial strength (AST) and up to 24% higher ductility indices than SFGC columns. The failure modes of both GFGC and SFGC columns were analogous. Both GFGC and SFGC columns revealed the same effect of eccentricity in the form of a decline in AST. A novel statistical model was suggested for predicting the AST of GFGC columns. The outcomes of the experiments, finite element simulations, and theoretical results show that the models can accurately determine the AST of GFGC columns.

2021 ◽  
pp. 136943322110073
Author(s):  
Yu Cheng ◽  
Yuanlong Yang ◽  
Binyang Li ◽  
Jiepeng Liu

To investigate the seismic behavior of joint between special-shaped concrete-filled steel tubular (CFST) column and H-section steel beam, a pseudo-static test was carried out on five specimens with scale ratio of 1:2. The investigated factors include stiffening types of steel tube (multi-cell and tensile bar) and connection types (exterior diaphragm and vertical rib). The failure modes, hysteresis curves, skeleton curves, stress distribution, and joint shear deformation of specimens were analyzed to investigate the seismic behaviors of joints. The test results showed the connections of exterior diaphragm and vertical rib have good seismic behavior and can be identified as rigid joint in the frames with bracing system according to Eurocode 3. The joint of special-shaped column with tensile bars have better seismic performance by using through vertical rib connection. Furthermore, a finite element model was established and a parametric analysis with the finite element model was conducted to investigate the influences of following parameters on the joint stiffness: width-to-thickness ratio of column steel tube, beam-to-column linear stiffness ratio, vertical rib dimensions, and axial load ratio of column. Lastly, preliminary design suggestions were proposed.


2019 ◽  
Vol 281 ◽  
pp. 01006 ◽  
Author(s):  
Majid M.A. Kadhim ◽  
Mohammed J Altaee ◽  
Ali Hadi Adheem ◽  
Akram R. Jawdhari

Fibre reinforced cementitious matric (FRCM) is a recent application of fibre reinforced polymer (FRP) reinforcement, developed to overcome several limitations associated with the use of organic adhesive [e.g. epoxies] in FRPs. It consists of two dimensional FRP mesh saturated with a cement mortar, which is inorganic in nature and compatible with concrete and masonry substrates. In this study, a robust three-dimensional (3D) finite element (FE) model has been developed to study the behaviour of slender reinforced concrete columns confined by FRCM jackets, and loaded concentrically and eccentrically. The model accounts for material nonlinearities in column core and cement mortar, composite failure of FRP mesh, and global buckling. The model response was validated against several laboratory tests from literature, comparing the ultimate load, load-lateral deflection and failure mode. Maximum divergence between numerical and experimental results was 12%. Following the validation, the model will be used later in a comprehensive parametric analysis to gain a profound knowledge of the strengthening system, and examine the effects of several factors expected to influence the behaviour of confined member.


2011 ◽  
Vol 306-307 ◽  
pp. 733-737
Author(s):  
Xu Dan Dang ◽  
Xin Li Wang ◽  
Hong Song Zhang ◽  
Jun Xiao

In this article the finite element software was used to analyse the values for compressive strength of X-cor sandwich. During the analysis, the failure criteria and materials stiffness degradation rules of failure mechanisms were proposed. The failure processes and failure modes were also clarified. In the finite element model we used the distributions of failure elements to simulate the failure processes. Meanwhile the failure mechanisms of X-cor sandwich were explained. The finite element analysis indicates that the resin regions of Z-pin tips fail firstly and the Z-pins fail secondly. The dominant failure mode is the Z-pin elastic buckling and the propagation paths of failure elements are dispersive. Through contrast the finite element values and test results are consistent well and the error range is -7.6%~9.5%. Therefore the failure criteria and stiffness degradation rules are reasonable and the model can be used to predict the compressive strength of X-cor sandwich.


Author(s):  
Ying Yue ◽  
Walter Villanueva ◽  
Hongdi Wang ◽  
Dingqu Wang

Abstract Vessel penetrations are important features of both pressurized water reactors and boiling water reactors. The thermal and structural behaviour of instrumentation guide tubes (IGTs) and control rod guide tubes (CRGTs) during a severe accident is vital in the assessment of the structure integrity of the reactor pressure vessel. Penetrations may fail due to welding failure, nozzle rupture, melt-through, etc. It is thus important to assess the failure mechanisms of penetrations with sufficient details. The objective of this paper is to assess the timing and failure modes of IGTs at the lower head during a severe accident in a Nordic boiling water reactor. In this study, a three-dimensional local finite element model was established using Ansys Mechanical that includes the vessel wall, the nozzle, and the weld joint. The thermo-mechanical loads of the finite element model were based on MELCOR results of a station blackout accident (SBO) combined with a large-break loss-of-coolant accident (LBLOCA) including an external vessel cooling by water as a severe accident management strategy. Given the temperature, creep strain, elastic strain, plastic strain, stress and displacement from the ANSYS simulations, the results showed the timing and failure modes of IGTs. Failure of the IGT penetration by nozzle creep is found to be the dominant failure mode of the vessel. However, it was also found that the IGT is clamped by the flow limiter before the nozzle creep, which means that IGT ejection is unlikely.


Author(s):  
Abm Hasan ◽  
H. Mahfuz ◽  
M. Saha ◽  
S. Jeelani

Flip-chip electronic package undergoes thermal loading during its curing process and operational life. Due to the thermal expansion coefficient (CTE) mismatch of various components, the flip-chip assembly experiences various types of thermally induced stresses and strains. Experimental measurement of these stresses and strains is extremely tedious and rigorous due to the physical limitations in the dimensions of the flip-chip assembly. While experiments provide accurate assessment of stresses and strains at certain locations, a parallel finite element (FE) analysis and analytical study can complementarily determine the displacement, strain and stress fields over the entire region of the flip-chip assembly. Such combination of experimental, finite element and analytical studies are ideal to yield a successful stress analysis of the flip-chip assembly under the various loading conditions. In this study, a two-dimensional finite element model of the flip-chip consisting of the silicon chip, underfill, solder ball, copper pad, solder mask and substrate has been developed. Various stress components under thermal loading condition ranging from −40°C to 150°C have been determined using both the finite element and analytical methods. Stresses such as (σ11, σ12, ε12 etc. are extracted and analyzed for the individual components as well as the entire assembly, and the weakest positions of the flip-chip have been discovered. Detailed description of FE modeling is presented and the different failure modes of chip assembly are discussed.


Proceedings ◽  
2018 ◽  
Vol 2 (11) ◽  
pp. 591
Author(s):  
Karel A. van Laarhoven ◽  
Bas A. Wols

The failure of joints plays an important role in the overall performance of mains. One of the prevalent failure modes at polyvinyl chloride (PVC) joints is the rupture of pipe or joint, which may occur due to high angular deflection of the pipe with respect to the joint, caused by differential soil settlement. The present paper reports the construction and use of a finite element model to determine the maximum angular deflection of a variety of PVC joints in different loading situations. The resulting acceptable deflections vary between 3° and 8° per side, which differs significantly from installation guidelines. The results will support drinking water companies in substantiating the prioritization of maintenance and inspection.


Author(s):  
Joseph E. D. Hess

Impulsively loaded pressure vessels are often closed using a bolted joint configured in a double staggered row pattern. The bolted joint design must maintain the placement of the vessel opening covers to support the structural integrity of the shell and also provide the necessary preload of sealing surfaces for leak prevention. Good design practice suggests configuring tensile loaded bolted joints with a double rows pattern in order to minimize prying against the bolt head induced by localized moments. Double bolt row patterns allow moments induced by load offsets to be reacted through contact of the faying surfaces of the bolted members and if separation occurs by differential axial loading of the two bolt rows. This acts to reduce direct prying of the mated members against the bolt heads. Material cost and operational time savings could be realized if a single bolt row design with acceptable performance was implemented. In this paper a detailed finite element model is described and calculation results are presented for two vessel configurations subjected to an impulsive load; a double staggered 64 bolt pattern and a single row 32 bolt pattern. Finite element results are compared to each other and to the rules of ASME Code Case 2564 in Section VIII, Division 3. Special attention is given to the loading induced in the bolts and to the relative deflection of faying surfaces containing seals. It will be shown that reducing the bolt count per opening from 64 to 32 results in increased peak response of the bolts, seal opening gaps, and shell. Nonetheless a single row bolt pattern does appear feasible and within the bounds of the Code Case.


2011 ◽  
Vol 94-96 ◽  
pp. 641-646
Author(s):  
Zhao Qiang Zhang ◽  
Yong Yao

Based on the constitutive models of steel and core concrete,the failure modes and the load-displacement curves of the solid multibarrel tube-confined concrete columns(CHS inner and SHS outer) under monotonic loading are calculated by using finite element analysis (FEA) method.The analytical results reveal the rules of stress distribution in steel and core concrete.The influences of axial compression ratio, yield strength of steel tube and concrete on the load-displacement curves are discussed.Through the results,it is deeply known the working mechanism of members(CHS inner and SHS outer) subjected to the static loads.


1992 ◽  
Vol 114 (3) ◽  
pp. 507-514 ◽  
Author(s):  
A. Kahraman ◽  
H. Nevzat Ozguven ◽  
D. R. Houser ◽  
J. J. Zakrajsek

A finite element model of a geared rotor system on flexible bearings has been developed. The model includes the rotary inertia of shaft elements, the axial loading on shafts, flexibility and damping of bearings, material damping of shafts and the stiffness and the damping of gear mesh. The coupling between the torsional and transverse vibrations of gears were considered in the model. A constant mesh stiffness was assumed. The analysis procedure can be used for forced vibration analysis of geared rotors by calculating the critical speeds and determining the response of any point on the shafts to mass unbalances, geometric eccentricities of gears, and displacement transmission error excitation at the mesh point. The dynamic mesh forces due to these excitations can also be calculated. The model has been applied to several systems for the demonstration of its accuracy and for studying the effect of bearing compliances on system dynamics.


Author(s):  
Mohamad Elani ◽  
Yehya Temsah ◽  
Hassan Ghanem ◽  
Ali Jahami ◽  
Youmn Al Rawi

Structural elements subjected to impact loads have a different response than those subjected to static loads. This research studied the effect of using shear reinforcement to reduce the local damage occurred when an impact load applied on a prestressed concrete beam. An accurate finite element model was provided for the analysis using the advanced volumetric finite element modeling program (ABAQUS). The concrete material was defined using the built in concrete damage plasticity model (CDP), that considers the nonlinear behavior of concrete when subjected to dynamic loading. All material properties were modified using the dynamic increase factor (DIF) to consider the effect of impact loading. It was realized that the failure was concentrated in the impact zone. However, using shear reinforcement reduced the permanent damage occurred due to impact.


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