The Experts below are selected from a list of 24746961 Experts worldwide ranked by ideXlab platform
Mohamed Mostafa Ibrahim - One of the best experts on this subject based on the ideXlab platform.
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behavior of i beam bolted extended end plate moment connections
Ain Shams Engineering Journal, 2013Co-Authors: Abdelrahim K Dessouki, Ahmed Hassan Youssef, Mohamed Mostafa IbrahimAbstract:Abstract Pretensioned extended, bolted end-plate moment connections are very popular due to ease of fabrication and erection. In order to identify the effect of different parameters on the behavior of the connection, a three-dimensional finite element model that accounts for both geometrical and material non-linearities is developed using the multi-purpose software package ANSYS. A parametric study is conducted using this model on two end-plate configurations: four bolts and multiple row extended end plates. The studied parameters were as follows: beam depth, end-plate thickness, bolts diameter, bolts pitch, bolts gage, and end-plate stiffener. Then, yield line analysis is used to propose equations for the end-plate bending capacity. A design model is assumed for bolt forces analysis, and design equations are proposed. The proposed equations are compared to the finite element results and the current design codes.
Naj Aziz - One of the best experts on this subject based on the ideXlab platform.
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A New Equation for the Shear Strength of Cable Bolts Incorporating the Energy Balance Theory
Geotechnical and Geological Engineering, 2017Co-Authors: Haleh Rasekh, Jan Nemcik, Ali Mirzaghorbanali, Naj AzizAbstract:The application of cable bolts as a secondary support system is an increasing trend in underground coal mines worldwide. The performances of cable bolts have been evaluated under both axial and shear loading conditions. Two methods of testing cables for shear, single and double shear, have been recognised. This paper examines the shear behaviour of a variety of cable bolts under different pre-tension loads by double shear testing. Plain, spiral and the combination of both cable types were used in this study. The initial axial load and the type of cable bolts are the main factors affecting their shear strength. By increasing the axial pre-tension load, the peak shear load occurs at lower shear displacement. The failure angle due to cable bending across the joint at different pre-tension loads varied between 41° and 49°. This demonstrates that the ratio of axial and perpendicular displacements is almost constant and on average the failure occurs at about 45°. A novel analytical model is proposed to evaluate the shear behaviour of pre-tensioned fully grouted cable bolts subjected to double shearing. Energy and Fourier Series methods were incorporated in the model to simulate the shear behaviour of cable bolts. The comparison of the experimental results with the proposed model shows a good agreement.
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rock bolt corrosion an experimental study
Mining Technology, 2014Co-Authors: Naj Aziz, Peter Craig, Jan NemcikAbstract:AbstractThe effect of long term exposure of full size bolts to corrosive environments is presented. A special test rig was used to test four bolts under different loading conditions. Four X-grade identical profile bolts, each 21·7 mm core diameter (23·7 mm full diameter) were subjected to prolonged corrosion testing using acid sulphate water. The pH value of the circulated water varied between 3·4 and 4·3. The corrosion exposure test period lasted 3·5 years. Two bolts were axially loaded to 10 t and 20 t force respectively, the third bolt was subjected to a 360 Nm torsion load and the fourth bolt was left unstressed to act as a reference bolt. After the test period ended, the bolts were stripped of their corroded coatings and weighted for weight loss. The diameter of each bolt was subsequently measured, and the loaded bolt samples were first tested non-destructively for tensile cracks and then tested for tensile failure. No cracks were found on post-corrosion bolts tested non-destructively. The failure st...
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double shear testing of bolts
2003Co-Authors: Naj Aziz, Damian Pratt, Richard WilliamsAbstract:ABSTRACT: Double shear testing was carried out on fully grouted and axially tensioned bolts installed in two different types of three piece concrete blocks. The purpose of the study was to examine the behaviour of reinforced bolts in shear under different axial loading conditions. A total of 22 bolts were tested using three common types of bolts used in Australia. The differentiating factor in bolt selection was the surface profile configuration, and the role of such configuration on the load transfer characteristic of cement/resin and bolt interactions. The influence of different tensional loads on the load transfer characteristics of bolts was also examined. The study showed that the medium strength and the axial tensional load influenced the level of shear load. Higher bolt profile configuration was least affected by the increased axial tensional load changes. There was no clear relationship between the vertical displacement at elastic yield point and each of bolt type, applied axial tensional loads and the medium strength. However, the shear loads were found to increase with increasing tensional loads and that the bolt profile configuration had influenced the shear load.
Chantale Doucet - One of the best experts on this subject based on the ideXlab platform.
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performance of d bolts under dynamic loading
Rock Mechanics and Rock Engineering, 2012Co-Authors: Charlie C Li, Chantale DoucetAbstract:In this work, dynamic test results of D-Bolts are presented. The rock bolt specimens studied are 20 and 22 mm in diameter and 0.8–1.5 m in section length. The bolts were tested at an impact velocity of 5.4–6.2 m/s and with impact energy varying from 10 to 60 kJ. In total, over 50 drop tests were conducted during a period of three years. The dynamic tests show that a D-bolt section of 22 mm × 1.5 m can sustain an impact of 56 kJ of a dynamic impact and absorb 60 kJ of energy prior to failure. The maximum impact energy of the 22 mm bolt is thus 37 kJ/m of bolt and the maximum energy absorption is 40 kJ/m. The displacement of the D-bolt increases linearly with the impact energy. A theoretical solution has been obtained for the relationship between the impact energy and the displacement of the bolt. It states that the energy absorption of a D-bolt section is proportionally related to the volume of the bolt section and the tensile strength and ultimate strain of the bolt material. It was also found that the magnitude of the impact energy determines whether or not the bolt fails, while the impact momentum determines how long the impact lasts. The impact duration increases linearly with momentum as long as the bolt shank does not fail.
Abdelrahim K Dessouki - One of the best experts on this subject based on the ideXlab platform.
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behavior of i beam bolted extended end plate moment connections
Ain Shams Engineering Journal, 2013Co-Authors: Abdelrahim K Dessouki, Ahmed Hassan Youssef, Mohamed Mostafa IbrahimAbstract:Abstract Pretensioned extended, bolted end-plate moment connections are very popular due to ease of fabrication and erection. In order to identify the effect of different parameters on the behavior of the connection, a three-dimensional finite element model that accounts for both geometrical and material non-linearities is developed using the multi-purpose software package ANSYS. A parametric study is conducted using this model on two end-plate configurations: four bolts and multiple row extended end plates. The studied parameters were as follows: beam depth, end-plate thickness, bolts diameter, bolts pitch, bolts gage, and end-plate stiffener. Then, yield line analysis is used to propose equations for the end-plate bending capacity. A design model is assumed for bolt forces analysis, and design equations are proposed. The proposed equations are compared to the finite element results and the current design codes.
Maria Anna Polak - One of the best experts on this subject based on the ideXlab platform.
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finite element simulation of concrete slabs with various placement and amount of shear bolts
Procedia Engineering, 2017Co-Authors: Aikaterini S Genikomsou, Maria Anna PolakAbstract:Abstract Three-dimensional (3-D) finite element analysis (FEA) in ABAQUS software examines the punching shear behaviour of reinforced concrete slabs. Four interior reinforced concrete slab-column connections (one slab is without shear reinforcement, while the other slabs are with shear bolts) previously tested under static loading are analysed. The shear reinforced slabs differ in the amount of the shear bolts. The coupled plasticity damaged model previously calibrated is considered for modelling the concrete. In this paper, parametric studies are presented to examine the effect of the amount and placement of the shear bolts. The amount of shear bolts is increased by adding more rows of shear bolts and also decreased by considering less shear bolts in each row. Also, two different arrangements are studied: rectangular and radial. The adopted FEA model is used to analyse and investigate the failure modes, loads and the crack patterns of the slab-column connections. The numerical results are compared to two current design codes for punching shear (ACI 318-14 and EC2-2004).
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design considerations for shear bolts in punching shear retrofit of reinforced concrete slabs
Aci Structural Journal, 2013Co-Authors: Maria Anna PolakAbstract:This study addresses design aspects for the punching shear bolt retrofitting system for reinforced concrete flat slabs supported on columns. Shear bolts are an external type of reinforcement installed in existing slabs by first drilling small holes through the slab thickness, installing the bolts into them, and tightening the bolt nuts. Previous experimental research at the University of Waterloo showed the effectiveness of this system in increasing strength and ductility of existing slabs, with little changes in the slab’s appearance. The procedures for the design of the shear bolts and their installation in slabs are proposed in the paper. Recommendations are provided regarding the stem diameter, the head area and thickness, and the spacing and the layout of the bolts in a plane of a slab.
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seismic retrofit of reinforced concrete slab column connections using shear bolts
Aci Structural Journal, 2009Co-Authors: Maria Anna PolakAbstract:Shear bolts are a new punching shear retrofit method for existing flat slab structures. This paper describes an experimental investigation on the application of shear bolts to reinforced concrete slab-column connections subjected to increasing cyclic lateral drift and constant gravity loading. Shear bolts, as transverse shear reinforcement, were installed externally in three specimens in holes drilled through the slabs? thickness in the vicinity of the columns. The test results show that shear bolts increase lateral load-resisting capacity, lateral drift capacity at peak and ultimate loads, and ductility of the slab-column connections. Shear bolts also change the failure mode of the slab-column connections from brittle to ductile and increase the energy dissipation capacity. Although the conclusions are made specifically for shear bolt retrofitted slabs, some of these findings can also be helpful in enhancing understanding of the behavior of flat reinforced concrete slabs with and without shear reinforcements.
