Load Distribution Ratio Research Articles

연속지지 RC 깊은 보의 부정정 스트럿-타이 모델 및 하중분배율 (II) 적합성 평가

In this study, ultimate strengths of 51 continuous reinforced concrete deep beams were evaluated by the ACI 318M-08`s strut-tie model approach implemented with the presented indeterminate strut-tie model and load distribution ratio of the companion paper. The ultimate strengths of the continuous deep beams were also estimated by the shear equations derived based on experimental results, conventional design codes based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the presented strut-tie model and load distribution ratio was examined through the comparison of the strength analysis results classified according to the primary design variables of shear span-to-effective depth ratio, flexural reinforcement ratio, and concrete compressive strength. The present study results of ultimate strengths obtained using the indeterminate strut-tie model and load distribution ratio of the continuous deep beams agree fairly well with those obtained using other approaches. In addition, the present approach reflected the effect of the primary design variables on the ultimate strengths of the continuous deep beams consistently and accurately. Therefore, the present study will help structural designers to conduct rational and practical strut-tie model designs of continuous deep beams.

Predicting the effect of tray malalignment on risk for bone damage and implant subsidence after total knee arthroplasty

Tibial tray malalignment has been associated with increased subsidence and failure. We constructed a finite element model of knee arthroplasty to determine the biomechanical factors involved in increasing the risk of subsidence with malalignment. Four fresh-frozen human knees were implanted with a tibial tray and subjected to forces representative of walking for up to 100,000 cycles. Cyclic displacement was measured between the tray and proximal tibia. The vertical load was shifted medially to generate a load distribution ratio of 55:45 (medial/lateral) to represent neutral alignment or 75:25 to represent varus alignment. Subjected specific geometry and material properties were obtained from qCT scans of tibia to construct a finite element model. The tray was subjected to a single load cycle representing experimental conditions. Tray displacement computed by the model matched that measured experimentally. Forces representing varus tray alignment generated greater strains in the proximal tibia and a greater volume of bone was subjected to strains higher than the fatigue threshold. Local compressive strains directly correlated with experimental subsidence and failure. Our results indicate that failure after tray malalignment is likely due to fatigue damage to the proximal tibia rather than shear across the implant-bone interface or failure of the cement mantle.

VERTICAL LOADING TEST OF SMALL BUILDING FOUNDATIONS USING TAPERED PILE

Long term loading test of the decreasing effect of settlement about small building foundations using tapered pile were conducted. We used basis reinforced with tapered pile and straight pile. This paper presents the outline of the loading tests and results of the tests and so on. From the studies, analyzes about settlement of foundation and the load distribution ratio of base slab and pile.

A 4WD Omnidirectional Wheelchair with Enhanced Step Climbing Capability

In developing an omnidirectional wheelchair tilted to climb single high steps, we enhanced standard step climbing by introducing a four-wheel drive (4WD). One pair of front and back wheels is connected by transmission belts to rotate in unison with a drive motor, i.e., synchrodrive transmission. To avoid wheel slippage as the mechanism turns, two omniwheels are installed in front and two regular tires in back, enabling the front wheels to slide freely sideways while the two back wheels continuously contact the ground. A third motor on the 4WD platform rotates the chair at the center of the mobile base around the vertical axis. The 4WD enhances step climbing over that of standard wheelchairs, but back wheels limit the step height climbed, meaning that front wheels climb higher steps than back wheels. We analyzed 4WD statics to clarify differences in front and back wheel step climbing, finding that drive torque caused the difference and that this influence depends on the wheelbase and vehicle weight distribution ratio of the front and back wheel axes. We varied the load distribution ratio among wheels to maximize back wheel step climbing. To do so, we developed chair tilting with a linear drive and an inclination sensor. The linear drive changes the chair's tilt angle for keeping the wheelchair statics and to vary positioning of the center of gravity (COG) to enable back wheels to climb steps more efficiently. To confirm the effectiveness of chair tilting in this scheme, we tested step climbing in experiments in which a prototype wheelchair carrying a user climbed a 90 mm step, but the back wheels failed when chair tilting was disabled.

Design of a novel semi-tracked air-cushion vehicle for soft terrain

In order to improve the crossing ability and the tractive performance of a vehicle operating on soft and wet terrain, the travelling mechanism must be properly designed and the adaptation ability to the changes of prevailing operation conditions is obviously needed. Based on the previous researches and developments of a wheeled air-cushion vehicle and a semi-walking wheeled air-cushion vehicle, a new hybrid vehicle that combines air-cushion technology with a travelling mechanism, i.e. a semi-tracked air-cushion (STAC) vehicle, has been developed. This paper proposed a new design principle for the semi-track air-cushion vehicle. A novel structure, i.e. a flexible joint mechanism as the prototype suspension system, is particularly described. Based on theoretical analysis, an optimisation model is established for minimising total power consumption. Experiments have been carried out to investigate the relationships among load distribution ratio, slip ratio, clearance height, vehicle speeds, resistances and power consumption in given terrain conditions. Experiment and simulation results showed that the developed vehicle can meet the demand of tractive and transport efficiency with its optimal state of using minimum total power consumption, and also satisfactory directional stability and ride comfort performances can be obtained.

Dynamic load distribution and tractive performance of a model tractor

The effect of dynamic load distribution on the tractive efficiency, torque ratio, traction ratio and power distribution of a 1 4 scaled model tractor was studied under two different soil conditions. The effects of the interactions of dynamic load distribution with slip and total dynamic load were investigated. A relationship between tractive coefficients and dynamic load distribution ratio was proposed.

Stress Analysis of Spur Gears in Consideration of the Ratio of Contact

This paper shows a new method for calculating the load distribution ratios and stress in spur gears by using the finite element models with many gear teeth. The results about the ratios of load taken by meshing gear tooth to the full load and the stress distribution show a noticeable difference between the analysis assuming that the load is shared between 2 pairs of teeth and the one assuming that it is carried by a single pair of teeth. This method makes it possible to clarify the effects of the ratio of contact and the addendum modification coefficience upon the load distribution ratio, stress distribution in gears and the stress concentration in the fillet at the base of the tooth.

Correlations between cone resistance and vane shear strength in some Scandinavian soft to medium stiff clays: Discussion

The writers thank Ladanyi and Vogan for their interesting discussions, and in particular for adding their field measurements to the data given in the paper. The results reported by Ladanyi are important since they present reasonably long term measurements of socket base stresses. The results show that even in fractured rock the load distribution ratio between the end bearing and bond components of stress support the findings of Osterberg and Gill (1973) as shown on their Figs. 1 and 2. Vogan raises the possibility that load transfer to the socket base may be stress dependent;

歯車かみあい試験機の試作研究

When a pair of gears are in mesh, the transmission torque will vary due to the friction of the tooth flank. Through measuring, recording and analyzing of this torque variation, we shall be able to know the coefficient of friction of the tooth flank and the load distribution ratio. Furthermore if we use a gear with a true involute tooth profile for one gear, we can find tooth profile error of its mate gear. Making use of the method of measurement and analysis of torque variation, we have made a new type gear rolling tester. This tester can test the transmission efficiency of the gear and such defects as burrs and flaws of tooth flank in addition to the before mentioned tests. This report was also made on the results obtained by using this gear rolling tester to measure and analyze the torque variations in a few gears.