Force Distribution Ratio Research Articles

Optimum Strut-and-Tie Models for Reinforced Concrete Beams

In this study, the authors suggested three optimum strut-and-tie models (STMs), which consider all reinforced concrete (RC) beams' failure behavior characteristics. The recommended models are valid for the RC beams with a shear span ratio (a/d) of less than 4.5. For each model, the authors also proposed a force distribution ratio, described by the portion of force carried by a truss mechanism, to assist structural designers in conducting the appropriate design using the current design codes' STM methods. In determining the force distribution ratios, the authors incorporated the influences of the main design variables, such as the a/d ratio, flexural rebar ratio, and concrete strength. The authors verified the appropriateness of the suggested STMs and force distribution ratios by using them for the strength verification of 758 RC beams tested to failure. The proposed STMs and force distribution ratios predicted the RC beams' failure strength quite well. The average test-to-predicted strength ratios (and coefficient of variations) by the present study and conventional STM models of design codes were 1.07 (21.3%) and 1.75 – 1.82 (27.6 – 45.7%), respectively.

The Vertical Behaviors of Dissimilar Pile Composite Foundations over Inclined Bedrock

Pile composite foundations (PCFs) have been commonly applied in reinforcement engineering to adjust the vertical stiffness of foundations, due to the displacement control design criteria for foundations. PCFs that have dissimilar pile lengths, located over inclined bedrock, have shown significantly different vertical behaviors from PCFs with equal pile lengths, placed over a semi-infinite medium. However, the vertical behaviors of dissimilar PCFs over inclined bedrock cannot be predicted with the current theoretical methods, although they have been widely adopted in engineering. An analytical method is proposed in this investigation to analyze the vertical bearing characteristics of dissimilar PCFs over inclined bedrock. A pile–soil system is decomposed into fictitious piles and extended soil, and then a control equation to determine the axial force along the fictitious piles is established, stemming from the compatibility conditions between them. The vertical behaviors of dissimilar PCFs can be obtained by solving the control equation with iterative procedures, and the equation is verified by two field load tests of single piles from the Honghe bridge and a numerical case. Then, the settlement and load transfer behaviors of 3 × 1 dissimilar PCFs and their influence factors are analyzed, and the results are as follows. (1) Obvious differences can be observed concerning the axial force distribution, settlement w, and load-sharing ratio (LSR) of each pile element for different pile–soil stiffness ratios (Ep/Es). (2) The LSR of pile 1 increases from 0.074 to 0.253 for the rigid pile and from 0.062 to 0.161 for the flexible pile condition when the cushion stiffness Kc changes from 1 × 104 kN/m to 3 × 108 kN/m. The non-dimensional vertical stiffness of the foundation, N0/wdEs, increases from 10.21 to 28.95 for the rigid pile condition and increases from 8.69 to 14.44 for the flexible pile condition, when Kc increases from 1 × 104 kN/m to 4 × 105 kN/m. (3) The neutral layer depth of the pile zn, the average settlement w, and the differential settlement wd of each element head decrease with Kc, and no negative friction zone exists (zn = 0 m) for all the pile elements when Kc> 2 × 105 kN/m. (4) The N0/wdEs decreases with the distance between the pile bottom and the inclined bedrock Δ. For the rigid and flexible pile conditions, the N0/wdEs is 22.16 and 13.48 for Δ = 1 m, and 13.13 and 10.10 for Δ = 8 m. The wd reaches 16.7 mm and 4.0 mm for Δ = 1 m and Δ = 8 m, respectively. (5) The N0/wdEs increases almost linearly with an increase in l/d for the rigid pile condition, and it gradually decreases for the flexible pile condition. The developed model can improve the design and analysis of PCFs located over inclined bedrock under vertical loading.

Finding a generic fixed brake force distribution through optimizing hydraulic brake system parameters to prevent wheel lock

Purpose The paper aims to identify a suitable generic brake force distribution ratio (β) corresponding to optimal brake design attributes in a diminutive driving range, where road conditions do not exhibit excessive variations. This will intend for an appropriate allocation of brake force distribution (BFD) to provide dynamic stability to the vehicle during braking. Design/methodology/approach Two techniques are presented (with and without wheel slip) to satisfy both brake stability and performance while accommodating variations in load sharing and road friction coefficient. Based on parametric optimization of the design variables of hydraulic brake using evolutionary algorithm, taking into account both the laden and unladen circumstances simultaneously, this research develops an improved model for computing and simulating the BFD applied to commercial and passenger vehicles. Findings The optimal parameter values defining the braking system have been identified, resulting in effective β = 0.695 which enhances the brake forces at respective axles. Nominal slip of 3.42% is achieved with maximum deceleration of 5.72 m/s2 maintaining directional stability during braking. The results obtained from both the methodologies are juxtaposed and assessed governing the vehicle stability in straight line motion to prevent wheel lock. Originality/value Optimization results establish the practicality, efficacy and applicability of the proposed approaches. The findings provide valuable insights for the design and optimization of hydraulic drum brake systems in modern automobiles, which can lead to safer and more efficient braking systems.

Horizontal and Uplift Bearing Characteristics of a Cast-In-Place Micropile Group Foundation in a Plateau Mountainous Area

Micropile groups have been progressively more frequently adopted in the construction of transmission tower bases due to their compact size and flexible construction advantages. However, the load-bearing characteristics and deformation mechanisms of micropile groups are complex, and the study of their coupling effects under combined loads remains unclear. Consequently, this paper presents a field static load test of micropile groups in a highland mountainous area. The analysis encompasses the axial force distribution and load-sharing ratio of micropiles. With a focus on micropile groups subjected to both uplift and horizontal combined loads, the coupled effects under different load combination ratios are examined using numerical simulation methods. The key findings are as follows: During the uplift loading process, the load distribution among individual piles is relatively uniform, with lower side friction resistance gradually coming into play to counterbalance the top load. The load–uplift displacement curve exhibits a steep characteristic, making it susceptible to sudden failure in practical engineering applications. Under the simultaneous action of uplift (V) and horizontal (H) loads, the unbalanced lateral frictional resistance on both sides of the pile segment induces additional bending moments, which is an important part affecting the load-coupling mechanisms. The uplift resistance capacity of micropile groups decreases with an increase in horizontal load, while the horizontal load-carrying capacity initially decreases and then increases with an increase in uplift load. The space enclosed by the yield envelope under combined load, and the vertical line of the ultimate load, is divided into a ‘failure zone’ and a ‘safety zone.’ In the design of the pile foundation, the uplift bearing capacity reduced by the ‘failure zone’ should be taken into account.

Research on the Updating Method of Vehicle Frame Finite Element Model

First, the strain gauges were pasted on the front and back tie rods of the vehicle for the sake of calibration. Under the designated working conditions, the strain data of the tie rods were collected via a data acquisition unit (DEWESoft). Meanwhile, the pressure of suspension cylinder was measured, the force distribution ratio of front axle and back axle was respectively calculated through the strain data and cylinder pressure data, and the calculation formula of the distribution ratio was obtained. The calculation results were verified through a traction test of the complete vehicle. In the end, the finite element model was updated according to the test data, followed by the analysis of the structural stiffness and strength. The method proposed in this paper will considerably contribute to the improvement of finite element analysis accuracy of the complete vehicle, and moreover, it can be promoted in the design of other similar structures, with a certain reference significance.

Regenerative Braking Control Strategy of Electric Vehicles Based on Braking Stability Requirements

Electric vehicles are effective way to solve energy and environmental problems, but the promotion and application of electric vehicles are suppressed by their limited endurance range seriously. The regenerative braking technology is an important method to increase the endurance range of the electric vehicle. During the braking process, the kinetic energy of the electric vehicle can be converted into electric energy and stored in the energy source device with the regenerative braking system, so the endurance range of the electric vehicle can be increased accordingly. In order to increase the efficiency of energy recovery, a regenerative braking strategy with the optimization distribution algorithm is proposed in this paper, and the braking forces of the front and rear axles are distributed optimally with variable ratios based on the braking strength. With the optimal braking force distribution ratio and related constraint conditions, the regenerative braking control strategy was designed to meet the braking stability and the maximum braking energy recovery. And then a simulation model of the braking control strategy was built with MATLAB/Simulink software, and the simulation tests on UDDS and NEDC cycle conditions were done to verify the effectiveness of the designed regenerative braking control strategy. Compared with the control strategy of ADVISOR software, the braking energy recovery efficiency was improved more than 51.9 % while maintaining the braking stability.

Performance‐based seismic design of the outrigger of a high‐rise overrun building with asymmetric vertical setback in a strong earthquake area

SummaryOutriggers, which should be systematically analyzed and designed based on seismic performance methods in the different seismic level actions, can improve the lateral stiffness of irregular high‐rise structures. In this paper, a concrete‐filled steel frame‐core tube‐outrigger structural system is adopted for a practical overrun high‐rise building with an obviously asymmetrical vertical setback in a high‐intensity seismic region. To ensure the seismic safety of irregular high‐rise building structures, the members of the outrigger are designed based on the seismic performance analysis method, and the complex joint region and slab of the outrigger floor are also refined and analyzed. In addition, the effect of outrigger on the damage states of the structural and member is evaluated using the elastic–plastic analysis method in the rare earthquake action. Finally, the seismic mitigation efficiency of the high‐rise structure with the viscous dampers installed on the outrigger floor is analyzed. The results indicate that the member size of the outrigger should be determined based on the performance objectives of the moderate earthquake action rather than the frequent earthquake action. The shear force distribution ratio of the outer frame located at the outrigger floor is obviously amplified, which shows that the cooperative bearing ability of the outer frame and the core tube is improved because of the outrigger action. The stress in the complex joint region of the outrigger, which satisfies the material strength requirement, is analyzed by the refined finite element analysis method. The slab of the outrigger floor, which should be strengthened to effectively transfer larger horizontal seismic shear force, has obvious damage in the rare earthquake action. The region of the structure with an outrigger that experiences significant damage in the rare earthquake action is located at the outrigger floor and adjacent upper domains rather than the bottom domains, which is different from that of a structure without an outrigger. The internal force of the outrigger member can be reduced by considering viscous damper action, but the seismic mitigation efficiency is not significant because of the limited number of dampers.

Hydrodynamic performance of a newly designed biplane-type hyper-lift trawl door for otter trawling

A biplane-type hyper-lift trawl door is newly designed to achieve stable handling while maneuvering, deploying, and stowing with excellent hydrodynamic performances for both bottom and midwater trawling. Flume-tank experiments were carried out to investigate the effect of the aspect ratio (λ, defined as the span b divided by chord c) on the hydrodynamic characteristics of the biplane-type hyper-lift trawl door with a camber ratio of 20% within a wide range of angles of attack (α). The maximum lift coefficients (CLmax) were 2.10 (λ = 1.0, α = 42°), 2.11 (λ = 1.6, α = 37°), and 2.06 (λ = 2.0, α = 28°). With a decreasing stall angle, the maximum lift coefficient remained constant (greater than 2). Considering the compactness and maneuverability of the biplane-type hyper-lift trawl door, an aspect ratio of 2 was adopted for the following experiments. The gap-chord ratio (G/c, G the gap between the fore and rear wings perpendicular to the chord direction) and stagger angle (θ, the included angle between the gap and the line connecting the leading edges of the fore and rear wings) expressing the positional relationship between the fore and rear wings of the biplane-type hyper-lift trawl door were set as 0.75, 0.9, and 1.0 and 20°, 30°, and 40°, respectively, to investigate the hydrodynamic characteristics further. The maximum lift coefficients and stall angles for the five biplane-type models were approximately 2.05 and 30°, respectively. Interestingly, these values were larger than the maximum lift coefficient and stall angle for a monoplane hyper-lift trawl door with the same aspect ratio (= 2) (CLmax = 1.78, α = 22°). This implies that the biplane-type structure contributes to enhancing the lift force and increasing the stall angle. The hydrodynamic forces of the fore and rear wings of the biplane-type hyper-lift trawl door were then calculated using a computational fluid dynamics approach. The lift coefficient for the rear wing was significantly higher than that for the fore wing before an angle of attack of 30° was reached. Nevertheless, the lift force distribution ratio for both the fore wing and the rear wing relative to the entire otter board approached 50%. On the other hand, the stall angle for the rear wing was approximately 30°, and that of the fore wing was around 38°. The fluid between the fore and rear wings tended to flow downstream and to successfully inhibit flow separation on the suction side of the fore wing.

Modeling and dynamics analyzing of a torsional-bending-pendular face-gear drive system considering multi-state engagements

A face-gear drive system has been extensively used in important transmission devices with strict requirements for size and weight such as helicopter reducer and so on. Its dynamic characteristics directly affect the stability and reliability of the equipment. A piecewise torsional-bending-pendular nonlinear dynamics model of the face-gear drive system is established to study its nonlinear dynamics and dynamic characteristics. The multi-state engagements including drive-side teeth engaging, teeth disengagement, back-side teeth engaging, and alternate engaging between single-teeth pair and double-teeth pairs caused by the couple of the backlash and the contact ratio being greater than 1.0 is considered. The change of the dynamic engaging force and load distribution ratio for the system is analyzed by numerical results under three different states engagement. The effects of the load coefficient, meshing frequency and the comprehensive transmission error on the dynamic characteristics and nonlinear dynamics of the system are studied based on three different Poincaré mappings defined by bifurcation diagrams, top Lyapunov exponent diagrams, phase portraits and variation curve of the dynamic engaging force. Results show that the complex phenomena such as teeth disengagement, drive-side and back-side impact occur with alternating meshing of the single and double pair teeth via the change of studied parameters. The research is helpful for the optimization of the face-gear drives.

Sequential Trajectory Generation for Dynamic Multi-Contact Locomotion Synchronizing Contact

This paper proposes a new framework to generate 3D multi-contact locomotion with low computation cost. The proposed framework consists of (a) the derivation of the prospect centroidal dynamics by introducing a force distribution ratio, where it can be represented with a formulation similar to the inverted pendulum’s one, and (b) the development of a fast computation method for generating a 3D center-of-mass (CoM) trajectory. Then (c) the ZMP reference is modified so that feasible contact wrench can be generated by a force distribution using the centroidal dynamics with the approximated friction cone. The proposed method allows to generate a trajectory sequentially and to change the locomotion parameters at any time even under variable CoM height. Then, the contact timing of each end-effector can be adjusted to synchronize with the actual contact with the environment by shortening or extending the desired duration of the support phase. This can be used to improve the robustness of the locomotion. The validity of the proposed method is confirmed by several numerical results in dynamic simulator: a CoM motion while changing the contact timing, a multi-contact locomotion considering a transition between biped and quadruped walking on an horizontal floor to move below obstacles. Finally, we also show a climbing stairs using handrail which requires dynamic changes of unilateral and bilateral contacts.

Accurate Brake Torque Estimation With Adaptive Uncertainty Compensation Using a Brake Force Distribution Characteristic

This paper presents an adaptive individual brake torque estimation method based on the characteristic of front-to-rear brake force distribution ratio. Most previous studies on tire force estimation have assumed that brake torques can be calculated out of brake pressure and given fixed brake gains. However, brake gains are proportional to brake pad friction coefficients, which are influenced significantly by operating or weather conditions. In this paper, it is assumed that the pad friction coefficients are the only uncertainties of the wheel dynamics model since they vary significantly according to the driving conditions. Furthermore, the vehicle specific brake force distribution is used to obtain the additional information. Thus, more practical aspects can be considered when calculating the brake torque. The developed algorithm is verified through simulations and experiments using a production vehicle, and it confirms that the estimation performance is improved significantly compared with that without uncertainty compensation.

Research on seismic behavior and shear strength of SRHC frame columns

The seismic behavior of steel reinforced high strength and high performance concrete (SRHC) frame columns was investigated through pseudo-static experiments of 16 frame columns with various shear span ratios, axial compression ratios, concrete strengths, steel ratios and stirrup ratios. Three kinds of failure mechanisms are presented and the characteristics of experimental hysteretic curves and skeleton curves with different design parameters are discussed. The columns’ ductility and energy dissipation were quantitatively evaluated based on seismic resistance. The research results indicate that SRHC frame columns can withstand extreme bearing capacity, but the abilities of ductility and energy dissipation are inferior because of SRHC’s natural brittleness. As a result, the axial load ratio should be restricted and some construction measures adopted, such as increasing the stirrup ratio. This research established effect factors on the bearing capacity of SPHC columns. Finally, an algorithm for obtaining ultimate bearing capacity using the flexural failure mode is established based on a modified plane-section assumption. The authors also established equations to determine shearing baroclinic failure and shear bond failure based on the accumulation of the axial load force distribution ratio. The calculated results of shear bearing capacity for different failure modes were in good agreement with the experimental results.

T-scan III 시스템을 이용한 하악 측방운동 시 교합접촉 양상의 분석

이 논문의 목적은 시간에 따른 교합의 변화를 측정할 수 있는 T-scan system을 이용하여 젊은 성인 남성(33명)정상교합에서의 하악골 측방운동 시 교합접촉 양상을 분석하는 것이다. 정해진 하악 위치에서의 교합접촉이 아닌, 기능적 범위 내에서 비작업측 교합이개 시점에서의 교합접촉 양상을 분류하고 분류된 군 간에 교합이개 시간, 측방유도 시 견치가 담당하는 교합력의 비율, 측방운동 시 가해지는 교합력 등을 비교하였다. 연구 결과 기존의 분류와는 다른 측방접촉들이 존재하였고 군기능 유도가 우세하게 나타났다. 교합이개 시간, 측방유도 시 견치가 담당하는 교합력의 비율, 측방운동 시 가해지는 교합력 등에서 군 간의 유의한 차이를 나타내었다. T-scan system은 교합접촉 양상을 분류하고 교합력, 교합이개 시간, 견치가 담당하는 교합력 비율 등의 항목을 비교 분석하는데 있어서 유용한 도구이다. The objective of this study was to analyze occlusal contact pattern of 33 young adult males with normal occlusion during lateral excursion using T-scan III system which can measure the dynamic occlusion. Occlusal contact patterns were examined and categorized in non-working side disclusion point(more functionally acceptable position) not canine-to-canine position. Disclusion time, occlusal force, and occlusal force distribution ratio of upper canine at disclusion point during lateral excursion movement was also measured and compared among the groups divided according to contact patterns. The results showed that group function was clearly more dominant than canine guidance and other occlusal contact patterns different with existing patterns were found. There were significantly difference between groups in variables of T-scan measurement. T-scan III system is effective tools to analyze and evaluate occlusal contact patterns, disclusion time, occlusal force, and occlusal force distribution ratio of upper canine at disclusion point.

3301 電気自動車における前後輪制駆動力配分による航続距離延長制御の実走行試験および台上評価(OS3-1 自動車の制御,OS3 交通・物流システムの制御,オーガナイズド・セッション(OS))

Recently, researches on cruising range extension for electric vehicles (EVs) have been conducted in the world. In this paper, proposal and evaluation of a range extension control system (RECS) are demonstrated. The proposed method optimizes front and rear driving-braking force distribution ratio. The effectiveness of the proposed method is verified by field and bench test.

The Dowel Group Action in Jointed Concrete Pavement

The wheel load transfer across a joints in concrete pavement is accomplished mainly by dowel bar system, dowels are installed in order to allow shear load transfer across slab joints. The dowel group action has been examined in this paper via from using of 3-D FE mode. Numerical model results are presented in four formats in this study, including shear force diagram, load transfer ratio by shear force, dowel shear force distribution and dowel shear ratio. The relationships between applied wheel load and dowel group action will be useful in the design and evaluation of dowel jointed concrete pavements.

Longitudinal study on occlusal force distribution in lower distal‐extension removable partial dentures with conus crown telescopic system

The purpose of this study was to examine longitudinal changes of the occlusal force distribution in lower distal-extension removable partial dentures with the conus crown telescopic system. Occlusal force applied to the denture and forces transmitted to the retainers were measured on several separate occasions from the insertion of new dentures to about 3 months after. The occlusal force distribution ratio to the retainers was calculated when a load of 20 N was applied to the denture. The results are summarized as follows: (i) The more posterior the loading point of occlusal force, the smaller was the ratio. When the occlusal force was applied to the most anterior artificial tooth, the ratio was 65-100% of the occlusal force. (ii) As the denture wearing time proceeded, the ratio was decreased. The smaller the ratio, the greater was the rate of its decrease.

Longitudinal study on occlusal force distribution in lower distal-extension removable partial dentures with circumferential clasps.

In this study, longitudinal changes of the occlusal force distribution ratio were examined in lower distal extension removable partial dentures with cast circumferential clasps. Occlusal force applied to the denture base and forces transmitted to the retainers were measured on several separate occasions from the insertion of new dentures to about 4 months after. Two rates of loading were chosen. One was simulated mastication (fast loading rate) and the other was 10 Ns-1 (slow loading rate). Location of the loading points were first premolar (P1), second premolar (P2) and first molar (P3) of the denture. The occlusal force distribution ratio to the retainers was calculated when a load of 20N was applied to the loading point. The results are summarized as follows: (1) The occlusal force distribution ratio at fast loading rate on P1 and P2 was changed until 1 or 1 1/2 months after the insertion of the new dentures, and then became constant. This constant value was 30% on P1, 20% on P2 and 10% on P3. (2) Slow loading rate produced a greater ratio than the fast loading rate on P2 and P3 while there were no remarkable differences in the ratio between both loading rates on P1.

小型三次元こう合力トランスデューサならびにモニターシステムの開発

To measure the occusal force three dimensionally on the tooth surface with the minimum jaw separation, we developed a miniature three dimensional transducer system utilizing force sensitive resin material and the computer program and tested its reliability.The transducer has 10.0mm diameter with 0.3mm thickness and a cone shape metal loading tip was attached on its top (3.0mm in height). Loads applied at the loading tip which could distributed through the metal cone to the sensing surface which is divided into four equal segments. By calculating the force distribution ratio among four segments, the vector of the load could be determined.1. Each section of the sensing surface showed fairly linear relation between load and output up to 5kg, so the sensor as a whole was capable for up to around 20kg force measurements.2. With the A/D and the computer program, the direction and amount of the applied force was calculated and visualized on the display.