Analytical Study on Bearing Capacity as a Structural System of Corroded Steel Bridge

2019 ◽  
Author(s):  
Kentaro Arimura ◽  
Takashi Yamaguchi ◽  
Kohei Funayama ◽  
Naoto Hirosawa
Keyword(s):  
Bearing Capacity ◽  
Carrying Capacity ◽  
Load Capacity ◽  
Corrosion Damage ◽  
Maximum Load ◽  
Load Carrying Capacity ◽  
Structural System ◽  
System Behavior ◽  
Load Carrying ◽  
Main Girder

<p>Deterioration of the road bridge built in the high growth period has become a big problem in Japan. Half of the reasons for rebuilding steel bridges are due to corrosion and many studies have been conducted on the load carrying capacity of girders with corrosion damage. On the other hand, the bridge is composed of multiple members such as main girder, lateral bracing and sway bracing. These members do not behave independently but behave as a structural system and have high redundancy. Many previous studies have focused on the load carrying capacity of corroded members independently and few studies focused on the evaluation of the system behavior and load carrying capacity of the bridge structures. It is required to clarify the structural system behavior of the bridge for more rational bridge design and repair reinforcement. In this study, full‐scale FE analysis for most standard steel I‐girder bridge considering corrosion damage was performed, and redundancy of the bridge structural system was examined varying corrosion position, corrosion degree, and number of main girder. According to the analysis results, a healthy girder resists the external load even after a girder with corrosion reaches the maximum load capacity and was confirmed that the maximum load capacity of the bridge system is much higher than that of the corroded girder end and has high redundancy. Furthermore, the difference on load‐bearing capacity when the number of main girders is changed are clarified focusing on l collapse process.</p>

Analytical study on repair method for steel I-girder bridges with corrosion damage considering its structural system behavior

2021 ◽  
Author(s):  
Ryoga Oura ◽  
Takashi Yamaguchi ◽  
Kentaro Arimura
Keyword(s):  
Carrying Capacity ◽  
Corrosion Damage ◽  
Load Carrying Capacity ◽  
Structural Members ◽  
Structural System ◽  
System Behavior ◽  
Girder Bridges ◽  
Load Carrying ◽  
Girder Bridge ◽  
The Individual

<p>Bridges are composed by many structural members which interact with each other to resist against various load combinations. Considering damage repair of one of its structural members, the relationship between the recovery of the individual load-carrying capacity due to the repair of a single member and the improvement of the load-carrying capacity of the structural system is not clear. In the present study, a full-scale FE analysis has been conducted for a steel I-girder bridge system with corrosion damages which have been repaired. The analysis considered, the structural system behavior, varying the repaired areas and the type of patch members. From the analytical results, it was found that, compared to the method in which the damaged portion is completely repaired, the amount of repair can be reduced by taking into account the structural system behavior and partially repair both the damaged and the adjacent intact girders.</p>

Strengthening Space Trusses by Diagonal Removal

1993 ◽  
Vol 8 (4) ◽  
pp. 231-239 ◽  
Author(s):  
Mousa Tabatabaei ◽  
Cedric Marsh
Keyword(s):  
Carrying Capacity ◽  
Load Capacity ◽  
Maximum Load ◽  
Load Carrying Capacity ◽  
Shear Forces ◽  
Equitable Distribution ◽  
Space Truss ◽  
Load Carrying ◽  
Space Trusses ◽  
Selection Of

Ideally a space truss is composed of bars each of which is suited to the load it carries. In practice, however, it is more convenient to use a limited number of bar sizes, thus only a few of the members will be fully stressed when the maximum load capacity of the space truss is reached. In order to effect a more equitable distribution of forces between chords of equal size such that more chord members are loaded close to their capacity, selected diagonals are removed to control the path followed by the shear forces, and thereby control the forces entering the chords. In this paper the effect of diagonal removal on space trusses is demonstrated and a method for selection of the diagonals whose removal gives optimum increase in the load carrying capacity of a space truss is described.

scholarly journals Small Scale Experiments to Assess the Bearing Capacity of Footings on the Sloped Surface

Eng ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 240-248
Author(s):  
Mohammad Nurul Islam
Keyword(s):  
Bearing Capacity ◽  
Carrying Capacity ◽  
Maximum Load ◽  
Scale Model ◽  
Small Scale ◽  
Load Carrying Capacity ◽  
Engineering Structures ◽  
Load Carrying ◽  
Limiting Condition ◽  
The Impact

Construction of civil engineering structures on or next to a slope requires special attention to meet the bearing capacity requirements of soils. In this paper, to address such a challenge, we present laboratory-scale model tests to investigate the effect of footing shape on the sloped surface. The model comprised of a well stiffened mild steel box with three sides fixed and one side open. We considered both with and without reinforcement to assess the effectiveness of reinforcement on the sloped surface. Also, we used three types of footing (i.e., square, rectangular, and circular) to measure the footing shape effects. We considered three different slope angles to evaluate the impact of the sloped face corresponding to the applied load and the reinforcement application. We obtained that the maximum load carrying capacity in the square footing was higher than the rectangular and the circular footing for both the reinforced and the unreinforced soil. With the increase of geo-reinforcement in all three footing shapes and three sloped angles, the load carrying capacity increased. We also noticed a limiting condition in geo-reinforcement placement effectiveness. And we found that with the increase of slope, the load bearing capacity decreased. For a steep slope, the geo-reinforcement placement and the footing shape selection is crucial in achieving the external load sustainability, which we addressed herein.

Optimum Design of Porous Gas Bearings With Maximum Load Carrying Capacity and Static Stiffness

2005 ◽  
Author(s):  
V. I. Grabovskii
Keyword(s):  
Flow Rate ◽  
Carrying Capacity ◽  
Load Capacity ◽  
Maximum Load ◽  
Optimum Shape ◽  
Load Carrying Capacity ◽  
Static Stiffness ◽  
Lubricant Flow ◽  
Load Carrying ◽  
Gap Height

The problem of optimum porous infinite sliding bearings design with isothermal compressed lubricant is solved. The sliders and journal bearings with maximum load carrying capacity or maximum a lubricant film static stiffness in conditions of restriction on the lubricant flow rate through a pored insert are examined. The found optimum shapes of bearings depend on problem parameters, determining property of lubricant and insert, conditions of feed and lubricant flow rate through an insert. Besides the bearings shape a size and position of insert are determined. The optimum shape features are the discontinuity of their gap height function and insert arrangement in the vicinity of this function breaking. In the case of journal bearing at fixed gap height only the best sizes of bushing and their positions from a point of view of maximum load capacity are founded. The method of calculus of variations is used.

scholarly journals The Effect of Geotextile Layers and Configuration on Soil Bearing Capacity

2021 ◽  
Vol 8 (6) ◽  
pp. 897-904
Author(s):  
Lubna Thamer ◽  
Hussein Shaia
Keyword(s):  
Tensile Strength ◽  
Bearing Capacity ◽  
Carrying Capacity ◽  
Maximum Load ◽  
Reinforced Soil ◽  
Soil Reinforcement ◽  
Silty Sand ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
The Impact

The term "reinforced soil" refers to a composite material with high tensile-strength components that enhance the soil's tensile strength. One of the most common kinds of geosynthetic fabric utilized for soil reinforcement is geotextiles. This article investigates woven geotextile's potential benefits in enhancing the maximum load-carrying capacity of footings resting upon silty sand soil. The foundation was constructed of a 10 mm thick strong carbon steel plate of 100 mm×100 mm. The factors examined in this research were the first geotextile layer's depth, the geotextile layer's width, the number of layers of reinforcing material, and the vertical spacing between geotextile layers. The impact of geotextile strengthening configurations on the load-carrying capacity of strengthened soil foundations was also studied. The results of the experiments indicated that geotextile reinforced soil could help to grow the soil bearing capacity. The testing findings revealed that the system with three geotextile layers, 0.25B vertical distance among geotextile layers, and a geotextile width of 5B, B denotes the plate's width, achieves the most significant bearing capacity. The test findings also revealed that the reinforcement configuration greatly impacted the reinforced silty sand on the foundation's behavior.

Maximum load carrying capacity of mobile manipulators: optimal control approach

Robotica ◽  
2009 ◽  
Vol 27 (1) ◽  
pp. 147-159 ◽  
Author(s):  
M. H. Korayem ◽  
A. Nikoobin ◽  
V. Azimirad
Keyword(s):  
Optimal Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Carrying Capacity ◽  
Nonholonomic Constraints ◽  
Maximum Load ◽  
Mobile Manipulators ◽  
Load Carrying Capacity ◽  
Maximum Payload ◽  
Load Carrying

SUMMARYIn this paper, finding the maximum load carrying capacity of mobile manipulators for a given two-end-point task is formulated as an optimal control problem. The solution methods of this problem are broadly classified as indirect and direct. This work is based on the indirect solution which solves the optimization problem explicitly. In fixed-base manipulators, the maximum allowable load is limited mainly by their joint actuator capacity constraints. But when the manipulators are mounted on the mobile bases, the redundancy resolution and nonholonomic constraints are added to the problem. The concept of holonomic and nonholonomic constraints is described, and the extended Jacobian matrix and additional kinematic constraints are used to solve the extra DOFs of the system. Using the Pontryagin's minimum principle, optimality conditions for carrying the maximum payload in point-to-point motion are obtained which leads to the bang-bang control. There are some difficulties in satisfying the obtained optimality conditions, so an approach is presented to improve the formulation which leads to the two-point boundary value problem (TPBVP) solvable with available commands in different softwares. Then, an algorithm is developed to find the maximum payload and corresponding optimal path on the basis of the solution of TPBVP. One advantage of the proposed method is obtaining the maximum payload trajectory for every considered objective function. It means that other objectives can be achieved in addition to maximize the payload. For the sake of comparison with previous results in the literature, simulation tests are performed for a two-link wheeled mobile manipulator. The reasonable agreement is observed between the results, and the superiority of the method is illustrated. Then, simulations are performed for a PUMA arm mounted on a linear tracked base and the results are discussed. Finally, the effect of final time on the maximum payload is investigated, and it is shown that the approach presented is also able to solve the time-optimal control problem successfully.

Development of Z-Factor for Circumferential Part-Through Surface Cracks in Dissimilar Metal Welds

2008 ◽  
Author(s):  
D.-J. Shim ◽  
G. M. Wilkowski ◽  
D. L. Rudland ◽  
F. W. Brust ◽  
Kazuo Ogawa
Keyword(s):  
Correction Factor ◽  
Carrying Capacity ◽  
Limit Load ◽  
Maximum Load ◽  
Load Carrying Capacity ◽  
Surface Cracks ◽  
Crack Driving Force ◽  
Dissimilar Metal ◽  
Load Carrying ◽  
J Estimation

Section XI of the ASME Code allows the users to conduct flaw evaluation analyses by using limit-load equations with a simple correction factor to account elastic-plastic fracture conditions. This correction factor is called a Z-factor, and is simply the ratio of the limit-load to elastic-plastic fracture mechanics (EPFM) maximum-load predictions for a flaw in a pipe. The past ASME Section XI Z-factors were based on a circumferential through-wall crack in a pipe rather than a surface crack. Past analyses and pipe tests with circumferential through-wall cracks in monolithic welds showed that the simplified EPFM analyses (called J-estimation schemes) could give good predictions by using the toughness, i.e., J-R curve, of the weld metal and the strength of the base metal. The determination of the Z-factor for a dissimilar metal weld (DMW) is more complicated because of the different strength base metals on either side of the weld. This strength difference can affect the maximum load-carrying capacity of the flawed pipe by more than the weld toughness. Recent work by the authors for circumferential through-wall cracks in DMWs has shown that an equivalent stress-strain curve is needed in order for the typical J-estimation schemes to correctly predict the load carrying capacity in a cracked DMW. In this paper, the Z-factors for circumferential surface cracks in DMW were determined. For this purpose, a material property correction factor was determined by comparing the crack driving force calculated from the J-estimation schemes to detailed finite element (FE) analyses. The effect of crack size and pipe geometry on the material correction factor was investigated. Using the determined crack-driving force and the appropriate toughness of the weld metal, the Z-factors were calculated for various crack sizes and pipe geometries. In these calculations, a ‘reference’ limit-load was determined by using the lower strength base metal flow stress. Furthermore, the effect of J-R curve on the Z-factor was investigated. Finally, the Z-factors developed in the present work were compared to those developed earlier for through-wall cracks in DMWs.

The Elastic-Softening Failure of Floating Beams

1988 ◽  
Vol 32 (01) ◽  
pp. 37-43
Author(s):  
Paul C. Xirouchakis
Keyword(s):  
Carrying Capacity ◽  
Maximum Load ◽  
Point Load ◽  
Negative Stiffness ◽  
Load Carrying Capacity ◽  
Perfectly Plastic ◽  
Load Carrying ◽  
Elastic Perfectly Plastic ◽  
The Moment ◽  
Elastic Softening

The solution is presented for an infinite elastic-softening floating beam under a point load. The response depends on two nondimensional parameters: the negative stiffness coefficient that characterizes the descending part of the moment-curvature curve, and the nondimensional softening region half-length. The solution exhibits two important features that the elastic-perfectly plastic solution does not show. First, in certain ranges of parameters, the elastic-softening beam has a clearly defined maximum load carrying capacity. Second, in some other ranges of parameters, the elastic-softening beam has a minimum load or residual strength. The beam stiffens up upon further deformation due to the reactions of the water foundation. Critical softening parameters are calculated that separate stable from unstable behavior.

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.

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