Combined Bending Load Research Articles

Fatigue property of U rib-crossbeam-deck connections in OBD under combined loading of bending and torsion

This paper investigates the fatigue property of U rib-crossbeam-deck connections in orthotropic steel bridge decks (OBD) under combined loading of bending and torsion by using the improved traction structural stress method. Applicability of the method for analyzing OBD under combined loads is validated by comparing the simulation results with the experimental results from the literature. The fatigue property of OBD in multiaxial stress states is studied by investigating the effects of the ratio of specimen width to length and combined loading amplitude. The trend and amplitude of the improved traction structural stress distribution change with an increase in the ratio of width to length.

Failure Analysis of Large-Diameter Coiled Tubing Based on Diameter Growth

Abstract Fatigue tests were conducted to analyze the fatigue behavior and diameter growth of large-diameter coiled tubing (CT) under the combined loads of bending and internal pressure. The experimental results reveal that mechanical limitations on the allowable diameter growth mean that the effective working life of CT at high pressures is only a fraction of the available fatigue life. The finite element software abaqus is used to further research the changes in diameter growth and to analyze the sensitivity of CT diameter growth to the main influencing factors, including internal pressure, tubing outside diameter (OD), wall thickness, yield strength, and bending radius. For CT with a diameter larger than 2 in., the diameter growth is sensitive to the above factors. As the bending and straightening cycles increase, the OD of the CT increases in association with obvious ovalization deformation, and the increase in the OD is closely related to the internal pressure load. The redistribution of material causes the wall thickness of the CT to become universally thinner. The ovality of the CT and the uneven decrease in wall thickness reduce the resistance to external extrusion. Therefore, it is becoming increasingly necessary to account for diameter growth as one of the key elements when predicting CT life or determining when to retire a string from service.

カテーテルの曲げと捩りの複合荷重における1段のステップ応力下で得られるクリープ変形に関する数値解析について

カテーテルの曲げと捩りの複合荷重における1段のステップ応力下で得られるクリープ変形に関する数値解析について

Torsion strength of single-box multi-cell concrete box girder subjected to combined action of shear and torsion

A model has been proposed that can predict the ultimate torsional strength of single-box multi-cell reinforced concrete box girder under combined loading of bending, shear and torsion. Compared with the single-cell box girder, this model takes the influence of inner webs on the distribution of shear flow into account. According to the softening truss theory and thin walled tube theory, a failure criterion is presented and a ultimate torsional strength calculating procedure is established for single-box multi-cell reinforced concrete box girder under combined actions, which considers the effect of tensile stress among the concrete cracks, Mohr stress compatibility and the softened constitutive law of concrete. In this paper the computer program is also compiled to speed up the calculation. The model has been validated by comparing the predicted and experimental members loaded under torsion combined with different ratios of bending and shear. The theoretical torsional strength was in good agreement with the experimental results.

Dynamic loading history and collapse analysis of the pipe during deepwater S-lay operation

In the deepwater S-lay operations depending on the required stinger radius and rollers configuration, relatively large plastic deformation is induced when the pipe passes over the stinger, under the combined loadings of bending, axial tension, roller reaction force and the pipelay vessel motion. The resulting plastic deformation does not vanish after the pipe leaves the stinger. It accumulates until the pipe reaches the seabed. The inherited residual deformation might reduce the collapse capacity of the pipe under the external pressure loading. The present paper investigates the dynamic loading history of the pipe during the S-lay operation based on a test-verified finite element model, and then calculates the residual plastic deformation of the pipe cross-section after the pipe reaches the seabed. Finally, the nonlinear collapse analysis is implemented based on the modified RIKS method to evaluate the capacity of the installation-induced deformed pipe. The results confirm that the deepwater S-lay operation will lead to obvious plastic deformation of the pipe, which decreases the pipe collapse capacity to some extent.

Stress Relaxation Behavior of Catheter Reinforced with Braid under Combined Loading for Bending and Torsion

The purpose of this research is to examine the physical property of the catheter, which made of soft nylon resin and is reinforced with thin stainless wires called braid. The effect of braid on the mechanical property of the catheter is revealed by investigating the relationship of the stress relaxation and the relative angle between the braid and the principal axis of stress under combined loading of bending and torsion. Inthe first place, in order to investigate the phenomenon of stress relaxation under combined loading, the experiments under single stage step strain have been carried out by changing the ratio of bending and torsion, and the relation between the coefficient of viscosity and the relative angle of the braid is revealed. In the second place, the experiment under two-stage step strain are conducted by changing the order of bending and torsion, and the effect of these loading histories on the visco-elastic properties is examined. Moreover, the numerical simulation under two-stage step strain is carried out by using the estimated coefficient of viscosity, and in this paper, the validity of this analytical model is confirmed by comparing with the experimental results.

Design Results of RC Members Subjected to Bending, Shear, and Torsion Using ACI 318:08 and BS 8110:97 Building Codes

AbstractIn this research, a comparative study was conducted on the amount of required reinforcement using American Concrete Institute (ACI) and British Standards Institution (BSI) building codes. The comparison included design cases of rectangular beam sections subjected to combined loads of bending, shear and torsion, and punching shear at slab–column connections. In addition, the study included comparison of the differences in the amount of reinforcement required owing to different codes’ factors of safety for design loads. It was found that the BS code requires less reinforcement than the ACI code does for the same value of design load. However, when the load safety factors are included in calculating the design loads, the values of the resulting design loads become different for each code, and in this case, the ACI was found to require less reinforcement than the BS. The punching shear strength of flat slab–column connections calculated using the ACI code was found to be more than that calculated usin...

Design of solid reinforced concrete beams

Higher experimentally measured load resistance of a solid beam than a hollow one, with similar reinforcement, led to theoretical and experimental investigations on how the concrete core participates in stress resistance. Stress analysis was carried out on solid beams subjected to combined load of bending, shear and torsion. The beams were 300 × 300 mm in cross-section and 3800 mm in length. A three-dimensional in-house non-linear finite-element program was used for numerical analysis. From this analysis, a stress distribution was selected and used in computational experiments. It was found that the concrete core participates in the beams' behaviour and strength and cannot be ignored when combined loads of bending, shear and torsion are present. Its participation depends partly on the ratio of the torsion-to-bending moment and the ratio of shear stress caused by torsion to the shear stress caused by shear force. This computational study was followed by experimental testing of three beams designed using the selected stress distribution. Experimental results on the behaviour and ultimate load showed an acceptable agreement with the design values. Most of the longitudinal and transverse reinforcement in the front side, where shear stresses are additive, reached yield stress near failure load. The longitudinal reinforcement in the rear side, where shear stresses are subtractive, reached near yield stress but the transverse reinforcement did not reach yield stress, especially in the beams where bending was dominant. In addition, it was found that the smaller the ratio of torsion to bending, the larger the failure load.

複合材料薄肉パイプの材料および構造設計の最適化

Simultaneous optimization of both material and structural design can be performed by using the characteristics that material design is possible for fiber reinforced composite materials. In the present paper, optimization of thin-walled composite cylindrical beam was carried out under combined loading of bending and axial torque. Several analytical models were proposed by taking account of the manufacturing processes of thin-walled cylindrical composite pipes. Among them, a non-uniform FW (filament winding) model is associated with a newly introduced manufacturing method of composite pipe. A numerical optimization method was used for the search of optimum design solution. As a result, it was confirmed that the optimization by using the non-uniform FW model was realistically useful for thin-walled cylindrical composite pipes.

Design of Composite Materials by Using the Intelligent Finite-Element Method. Determination of Laminated Construction in Consideration of Strength and Weight.

A personal computer program using the intelligent Finite-Element Method (FEM.) has been developed in order to analyze the components and its stacking sequence of laminate by which some design objects are satisfied. In this paper, the strength and the weight of laminate have been selected as the design objects. Taking these design objects into consideration, as the examples, a laminated plate under the conditions of bending and combined loads of bending and tension have been analyzed, and optimum laminated materials and stacking sequence for each condition have been determined. Therefore, it is recognized that the proposed intelligent FEM. in this paper is very useful for structure design of composite materials.

思考型有限要素法による複合材料設計 その１ 破壊則を基にした積層構成の決定

A personal computer program of Finite Element Method was developed in the past in order to analyze the stresses in composite materials. Although the mechanical behavior of composite materials can be analyzed by such a developed computer program, the component construction of laminates can not be obtained because it is very difficult to optimize the computational results by using an ordinary F.E.M.. On the other hand, the ratio of layer components can be calculated by the method of optimization, but not the lay-up sequence of laminates.In this paper, the personal computer program of intelligent F.E.M. with a new concept has been developed in order to analyze the component and lay-up sequence of laminates which satisfy the design objects. As an example of analysis, the material for each layer of a laminated panel under bending condition was selected and the thickness of laminae under combined loads of bending and tension was determined. The computational results were very reasonable for the composite structure. Therefore, it was recognized that the proposed intelligent F.E.M. is very useful for the structure design of composite materials.