scholarly journals Theoretical Study on the Flexural Behavior of Structural Elements Strengthened with External Pre-Stressing Methods

2021 ◽  
Vol 12 (1) ◽  
pp. 171
Author(s):  
Gouda A. Mohamed ◽  
Ahmed S. Eisa ◽  
Pavol Purcz ◽  
Mohamed H. El-Feky
Keyword(s):  
Carrying Capacity ◽  
Load Capacity ◽  
Flexural Behavior ◽  
Load Carrying Capacity ◽  
Structural Elements ◽  
Vertical Loading ◽  
Rc Frames ◽  
External Tendons ◽  
Straight Line ◽  
Load Carrying

This study aims to strengthen the flexural behavior of structural elements with external pre-stressing tendons, thereby improving their load-carrying capacity and increasing their resistance against the external load. Different techniques were used to apply external pre-stressed strengthening to RC beams and RC frames. Seven identical RC frames were analyzed: an original sample without an external tendon, two strengthened samples with external tendons at the positive bending zone, two strengthened samples with external tendons at the beam–column connection zone, a strengthened sample with external straight line tendons along the beam and, finally, a strengthened sample with external U-shape tendons along the beam of the frame. The analysis and the results were obtained using ANSYS WORKBENCH finite element (FE) program. Comparisons were performed between these techniques to determine which technique is better for strengthening. The failure mode, vertical deflection, column stress, load-carrying capacity, and ductility of the samples were listed and analyzed under four-point vertical loading. The results show that using external tendons significantly increases the load capacity and the stiffness of structural frames. Moreover, the tendon in the beam zone is more effective than the tendon in the column zone.

Susceptibility of strain-hardening cementitious composite to curing conditions as a retrofitting material for RC beams

2021 ◽  
Vol 16 ◽  
pp. 155892502110203
Author(s):  
Mohammad Iqbal Khan ◽  
Galal Fares ◽  
Yassir Mohammed Abbas ◽  
Wasim Abbass ◽  
Sardar Umer Sial
Keyword(s):  
Strain Hardening ◽  
Environmental Conditions ◽  
Carrying Capacity ◽  
Flexural Behavior ◽  
Load Carrying Capacity ◽  
Rc Beams ◽  
Curing Conditions ◽  
Flexural Members ◽  
Load Carrying ◽  
Curing Regime

Strain-hardening cement-based composites (SHCC) have recently been developed as repair materials for the improvement of crack control and strength of flexural members. This work focuses on strengthening and flexural enhancement using SHCC layer in tensile regions of flexural members under three different curing conditions. The curing conditions simulate the effect of different environmental conditions prevailing in the central and coastal regions of the Arabian Peninsula on the properties of SHCC as a retrofitting material. In this investigation, beams with SHCC layer were compared to control beams. The beams with SHCC layer of 50-mm thickness were cast. The results revealed that the flexural behavior and the load-carrying capacity of the normal concrete beam specimens under hot and dry environmental conditions were significantly reduced, lowering the ductility of the section. However, compressive strength is comparatively unaffected. Similarly, the hot curing conditions have also led to a notable reduction in the loading capacity of the beam with SHCC layer with a slight effect on its stiffness. On the other hand, steam-curing conditions have shown improvement in load-carrying capacity and a reduction in section ductility of the beam with SHCC layer. It was found that the structural unit retrofitted with SHCC layer was a curing-regime dependent as the tensile and strain-hardening properties of SHCC are highly sensitive to the alteration in the cement hydration process. A normal curing regime was found effective and satisfying the practical, cost, and performance requirements. Accordingly, a normal curing regime could be implemented to retrofit reinforced concrete (RC) beams with SHCC layers as recommended in the study.

Analysis of Seismic Performance of RC Frames with Centrally Reinforced Columns

2013 ◽  
Vol 671-674 ◽  
pp. 1319-1323
Author(s):  
Zi Xue Lei ◽  
Yu Hang Han ◽  
San Sheng Dong ◽  
Jun Qing Guo
Keyword(s):  
Seismic Performance ◽  
Cross Sections ◽  
Carrying Capacity ◽  
Pushover Analysis ◽  
Seismic Load ◽  
Load Carrying Capacity ◽  
Rc Columns ◽  
Rc Column ◽  
Rc Frames ◽  
Load Carrying

A centrally reinforced column is a new type of RC columns, formed by providing a reinforcement skeleton at the central part of the cross section of an ordinary RC column. Tests have shown that as compared with an ordinary RC column, this type of columns has a higher load carrying capacity and ductility. From the pushover analysis of a frame composed of ordinary RC columns and one consisting of centrally reinforced columns, their seismic performance under seismic load of 9-degree intensity was studied according to Chinese code, including target displacements, story-level displacements, interstory drifts, appearance and development of plastic hinges. The results indicate that although the dimensions of cross sections of columns in the frame with centrally reinforced columns are smaller than those of the ordinary frame, the former still has a higher overall load carrying capacity and seismic performance than the latter.

Performance of a Short Multi-Grooved Capillary Compensated Hydrostatic Journal Bearing

1968 ◽  
Vol 183 (16) ◽  
pp. 107-115
Author(s):  
J. K. Patrick ◽  
N. N. S. Chen
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Flow Characteristics ◽  
Lubricating Oil ◽  
Load Carrying Capacity ◽  
Straight Line ◽  
Load Carrying ◽  
Capillary Type ◽  
First Time ◽  
Oil Film Pressure

This paper presents the results of an extensive experimental investigation into the performance of a short multi-grooved bearing subjected to a range of static and alternating loads. Lubricating oil was supplied, at pressures of up to 2000 lb/in2, to capillary type restrictors connected to 10 closed-end axial grooves in the bearing. The bearing had a length/diameter ratio of 1/3 and operated with a journal speed and load frequency of 327 c/min. Measured load capacity, stiffness, and flow characteristics indicate that bearings of this type have a significant load-carrying capacity at zero journal speed and that the load capacity is increased by journal rotation. A feature of the journal behaviour under alternating loads is the movement of the journal centre along a straight line coincident with the load plane. The extensive oil film pressure surveys indicate for the first time the pressure distribution within narrow hydrostatic bearings and provide a basis for a realistic theoretical analysis of this type of bearing.

Influence of geometric parameters on the bump foil bearing performance

2019 ◽  
Vol 234 (7) ◽  
pp. 1017-1026
Author(s):  
Sadanand Kulkarni ◽  
Soumendu Jana
Keyword(s):  
Carrying Capacity ◽  
High Speed ◽  
System Development ◽  
Load Capacity ◽  
Radial Clearance ◽  
Load Carrying Capacity ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Load Carrying ◽  
Lift Off

High-speed rotating system development has drawn considerable attention of the researchers, in the recent past. Foil bearings are one of the major contenders for such applications, particularly for high speed and low load rotating systems. In foil bearings, process fluid or air is used as the working medium and no additional lubricant is required. It is known from the published literature that the load capacity of foil bearings depend on the operating speed, viscosity of the medium, clearance, and stiffness of the foil apart from the geometric dimensions of the bearing. In case of foil bearing with given dimensions, clearance governs the magnitude of pressure developed, whereas stiffness dictates the change in radial clearance under the generated pressure. This article deals with the effect of stiffness, clearance, and its interaction on the bump foil bearings load-carrying capacity. For this study, four sets of foil bearings of the same geometry with two levels of stiffness and clearance values are fabricated. Experiments are carried out following two factor-two level factorial design approach under constant load and in each case, the lift-off speed is measured. The experimental output is analyzed using statistical techniques to evaluate the influence of parameters under consideration. The results indicate that clearance has the maximum influence on the lift-off speed/ load-carrying capacity, followed by interaction effect and stiffness. A regression model is developed based on the experimental values and model is validated using error analysis technique.

Static characteristics of misaligned multiple axial groove water-lubricated bearing in the turbulent regime

2016 ◽  
Vol 231 (3) ◽  
pp. 385-398 ◽  
Author(s):  
Ravindra Mallya ◽  
Satish B Shenoy ◽  
Raghuvir Pai
Keyword(s):  
Reynolds Number ◽  
Friction Coefficient ◽  
Carrying Capacity ◽  
Journal Bearing ◽  
Load Capacity ◽  
Turbulent Regime ◽  
Load Carrying Capacity ◽  
Static Characteristics ◽  
Load Carrying ◽  
Turbulence Effects

The static characteristics of misaligned three-axial water-lubricated journal bearing in the turbulent regime are analyzed for groove angles 36° and 18°. Ng and Pan’s turbulence model is applied to study the turbulence effects in the journal bearing. The static parameters such as load-carrying capacity, friction coefficient, and side leakage are found for different degree of misalignment (DM). The change in flow regime of the lubricant from laminar to turbulent and the increase in misalignment, improved the load capacity of the bearing. For lightly loaded bearings, the friction coefficient of the bearing increased with the increase in Reynolds number.

Partially Textured Slider and Journal Bearing Analysis

2012 ◽  
Vol 58 (2) ◽  
Author(s):  
T. V. V. L. N. Rao ◽  
A. M. A. Rani ◽  
T. Nagarajan ◽  
F. M. Hashim
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Carrying Capacity ◽  
Journal Bearing ◽  
Load Capacity ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Bearing Analysis

The present study examines the influence of partial texturing of bearing surfaces on improvement in load capacity and reduction in friction coefficient for slider and journal bearing. The geometry of partially textured slider and journal bearing considered in this work composed of a number of successive regions of groove and land configurations. The nondimensional pressure expressions for the partially textured slider and journal bearing are derived taking into consideration of texture geometry and extent of partial texture. Partial texturing has a potential to generate load carrying capacity and reduce coefficient of friction, even for nominally parallel bearing surfaces.

scholarly journals Load-Carrying Capacity of Short Concrete Columns Reinforced with Glass Fiber Reinforced Polymer Bars Under Concentric Axial Load

2019 ◽  
Vol 9 (2) ◽  
pp. 1712-1719
Keyword(s):  
Carrying Capacity ◽  
Load Capacity ◽  
Plain Concrete ◽  
Concrete Columns ◽  
Reinforcement Ratio ◽  
Load Carrying Capacity ◽  
Rc Columns ◽  
Gfrp Bars ◽  
Glass Fiber Reinforced ◽  
Load Carrying

In this paper, 1 group of plain concrete square columns 150×150×600 mm and 11 groups of concrete columns reinforced with glass fiber reinforced polymer (GFRP) were cast and tested, each group contains of 3 specimens. These experiments investigated effect of the main reinforcement ratio, stirrup spacing and contribution of longitudinal GFRP bars on the load carrying capacity of GFRP reinforced concrete (RC) columns. Based on the experiment results, the relationship between load-capacity and reinforcement ratio and the plot of contribution of longitudinal GFRP bars to load-capacity versus the reinforcement ratio were built and analyzed. By increasing the reinforcement ratio from 0.36% to 3.24%, the average ultimate strain in columns at maximum load increases from 2.64% to 75.6% and the load-carrying capacity of GFRP RC columns increases from 3.4% to 25.7% in comparison with the average values of plain concrete columns. Within the investigated range of reinforcement ratio, the longitudinal GFRP bars contributed about 0.72%-6.71% of the ultimate load-carrying capacity of the GFRP RC columns. Meanwhile, with the same configuration of reinforcement, contribution of GFRP bars to load-carrying capacity of GFRP RC columns decreases when increasing the concrete strength. The influence of tie spacing on load-carrying capacity of reinforced columns was also taken into consideration. Additionally, experimental results allow us to propose some modifications on the existing formulas to determine the bearing capacity of the GFRP RC column according to the compressive strength of concrete and GFRP bars.

scholarly journals Contact Analysis and Static Load Carrying Capacity of Planetary Roller Screw Mechanism

2020 ◽  
Author(s):  
Nam Su Kim ◽  
Kyongho Kim ◽  
Sinhyok Jong
Keyword(s):  
Finite Element ◽  
Contact Stress ◽  
Carrying Capacity ◽  
Static Load ◽  
Load Capacity ◽  
Load Carrying Capacity ◽  
Elastic Plastic ◽  
Load Carrying ◽  
Roller Screw ◽  
Screw Mechanism

Abstract This paper aims to investigate the contact characteristics and static load carrying capacity of planetary roller screw mechanism (PRSM). Compared to the ball screw mechanism, the advantages of the PRSM are high stiffness, high load capacity, long travel life and compact structure, etc., since the PRSM possesses more contact points than ball screws in a comparable size. The actuated load is carried through the threaded surface contacts of the screw, the rollers and the nut and the contact characteristics of these components are very important for studying the wear, transmission accuracy and efficiency of a PRSM. Prior work has neglected to take a fundamental approach towards understanding the elastic-plastic contact characteristics of threaded surfaces under high loads and it is closely related to the static load carrying capacity of PRSM. Accordingly, in this paper, the contact characteristics of PRSM under the different working loads are modeled based on Hertz contact theory and the calculation formulas between normal force of thread turns and the elastic-plastic contact stress and deformation are derived. Then, it goes further to derive a calculation method of static load carrying capacity of PRSM based on simplified model of static load distribution. Finally, a verification model is developed by finite element method (FEM) to perform contact stress and strain analysis of PRSM. Besides, through the comparison of the results between the theory model and ANSYS Workbench finite element model verify the reliability of the theory.

scholarly journals FLEXURAL LOAD AND DEFLECTION BEHAVIOR OF STRUCTURAL BAMBOO FILLED WITH CEMENT MORTAR

2021 ◽  
Vol 83 (4) ◽  
pp. 31-39
Author(s):  
Gathot Heri Sudibyo ◽  
Nor Intang Setyo Hermanto ◽  
Hsuan-Teh Hu ◽  
Yanuar Haryanto ◽  
Laurencius Nugroho ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Carrying Capacity ◽  
Cement Mortar ◽  
Natural Material ◽  
Load Carrying Capacity ◽  
Structural Elements ◽  
Load Bearing ◽  
Four Point Bending ◽  
Bamboo Nodes ◽  
Load Carrying

Bamboo has been significantly and rapidly used to build temporal and permanent structures since time immemorial. However, this renewable natural material has a low bearing capacity, limiting its application to structures under light loads. Therefore, this research was carried out to determine an innovative scheme capable of enhancing bamboo's load-bearing by filling the cavity with cement mortar. Furthermore, a study was carried out to experiment flexural load carrying capacity and the deflection of mortar-filled structural bamboo by considering the diameter and node parameters. A total of 12 specimens were examined using a four-point bending protocol. The result showed the ultimate flexural load carrying capacity of mortar-filled bamboo specimens are higher than those of the conventional bamboo specimens. Specifically, mortar filled bamboo specimen with a diameter of 70 mm was significantly better, 41.10 and 47.06%, as compared than the conventional bamboo in terms of its flexural load carrying capacity for specimen without and with nodes, respectively. Increases in flexural load carrying capacity were also observed for the mortar-filled bamboo specimens having 80 and 90 mm diameter and these observed increases were recorded as 104.55 and 112.00%, and 48.72 and 60.74%, respectively for specimen without and with nodes. Furthermore, the deflection of mortar-filled bamboo elements are substantially greater than those of conventional. Finally, the advantages of the bamboo diameter and bamboo nodes on the flexural load carrying capacity indicated that these essential findings need to be carefully considered in designing structural elements for both mortar-filled and conventional bamboos.

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