Load Distribution Ratio Research Articles

Estimation of axial stiffness on existing and reinforcing piles in vertical extension remodeled buildings

In this study, the load distribution ratio (LDR) and axial stiffness of reinforcing piles in vertical extension remodeling structure will be investigated through numerical calculation and case studies. By comparing the results between existing and reinforcing piles, the efficiency of the reinforcing piles will be observed. To further understand the LDR of piles, the effect of elastic modulus of raft, pile end-bearing condition, raft rigidity, and the relative position of reinforcing pile in a group were investigated by using 3D FE analysis. The numerical model was validated based on actual field measurements. In addition, the method in estimating the axial stiffness of reinforcing piles (Kvr) was presented which is based on (1) the axial stiffness of existing piles (Kve) by using the 3D computer-based method, YSPR (Yonsei Piled Raft), and (2) by reducing the axial stiffness of existing piles by considering the aging and the deterioration process. The results of this can justify the necessity for settlement-based design and improvement of piled-raft foundation of vertical extension remodeling. The conclusions in this paper will significantly contribute to ensuring the safety and integrity of the structure during vertical extension remodeling process and throughout the service period.

Comparative study of load distribution ratio of various piled raft foundations based on coupled stiffness matrix

SummaryLoad distribution ratio of piled raft foundation was investigated based on an interactive foundation analytical method that considers the coupling effect between the stiffness of the superstructure, the piled raft, and the soil. Series of numerical analysis was performed to verify the proposed analytical routine in comparison with various methods and field measurements. Through the comparative studies between various piled rafts with different aspects, it was found that the proposed analytical method derived accurate results in structural response compared with actual field data, in settlement, load distribution ratio, and raft bending moment. And it was also found that the proposed analytical method was capable of considering interaction between superstructure and foundation in predicting the behavior of building structures. As a result, it was found that in most cases, the pile in the piled raft foundation supports a majority portion of the structural load. However, for cases where the length of the pile was short and acts as a short column, the load distribution ratio between raft and pile may be overturned and shows significantly different behavior and load distribution ratio.

Static electronic baropodometry in patients with metatarsalgia

Objective: To analyze the values obtained by electronic baropodometry in patients with metatarsalgia. Methods: A retrospective observational study of medical data (gender, height, weight, body mass index, foot laterality, shoe size and clinical diagnosis) and values obtained by static electronic baropodometry (load distribution and maximum and mean pressure) was performed. A total of 39 patients with clinical complaints of metatarsalgia were selected and subjected to static electronic baropodometry. Results: Female gender was more prevalent (58.9%) among patients, and 61.53% of the patients were overweight or obese. The mean maximum pressure was 1.76kgf/cm2, and the forefoot-to rearfoot load distribution ratio was 0.86. There was a significant correlation between body mass index and maximum pressure. No correlation was found with shoe size. Conclusion: The baropodometry values measured in this study were similar to those reported in the literature. Obese and overweight patients had a higher maximum pressure value, which suggests a higher risk of metatarsal pain in this population. Level of Evidence III; Diagnostic Studies; Study of non consecutive patients; Without consistently applied reference “gold” standard.

An optimum indeterminate strut-and-tie model for reinforced concrete corbels

The failure behavior of a reinforced concrete corbel is complicated due to the shear span-to-effective depth ratio, reinforcement patterns, load conditions, and material properties. In this study, an optimum first-order indeterminate strut-and-tie model that reflects all characteristics of the failure behavior is proposed for the rational design of reinforced concrete corbels with a shear span-to-effective depth ratio of less than 1.0. A load distribution ratio that transforms the indeterminate strut-and-tie model into a determinate model is also developed to help structural designers design reinforced concrete corbels using the strut-and-tie model methods of current design codes. For the development of the load distribution ratio, a material nonlinear finite element analysis of the proposed first-order indeterminate strut-and-tie model was conducted repeatedly by changing the combination of primary design variables of the corbels. To examine the validity of our results, the ultimate strengths of 294 reinforced concrete corbels tested to failure by other investigators were predicted using the proposed strut-and-tie model with the load distribution ratio, the existing determinate strut-and-tie models representing arch and truss load transfer mechanisms, and the American Concrete Institute 318 conventional design method based on a shear friction theory. The ultimate strengths predicted by the proposed strut-and-tie model agreed fairly well with the experimental results. The ratio of the experimental strength to the predicted strength (and coefficient of variation) was 1.09 (28.0%), implying that the proposed strut-and-tie model can represent the load transfer mechanisms of corbels most appropriately.

Investigation of the effect of load distribution along the face width and load sharing between the pairs in contact on the fracture parameters of the spur gear tooth with root crack

Abstract The magnitude and location of stress intensity factor (SIF) in mode I (KI), mode II (KII), mode III (KIII) relies mainly on the geometry and location of the crack tip, variation in magnitude of load due to multiple pair contact along the active profile and the distribution of the load along the face width of a spur gear drive. Mostly, in literature the calculation of SIF in gear were carried out either by using a two dimensional (2D) Finite element model (FEM) with point load for unit width or a three dimensional (3D) FEM with uniform / parabolic load distribution along the face width without considering load sharing effect between the multiple pairs in contact. In the present study, an attempt has been made to explore the significance of the load distribution along the face width and the load sharing between the pairs when the contact moves from the highest point of tooth contact (HPTC) to the lowest point of tooth contact (LPTC) on the SIF calculation. A comparative study has been made by using a validated 3D single tooth spur gear FEM with four different load cases such as case 1: Uniform load distribution along face width without considering load sharing between the pairs, case 2: Uniform load distribution along face width by including the effect of load sharing between the pairs, case 3: Actual load distribution along the face width without considering load sharing between the pairs, case 4: Actual load distribution along the face width by including the effect of load sharing between the pairs. The stiffness based approach was used to calculate the load distribution ratio (LDR) of a contact point along the contact line and the load sharing ratio (LSR) between the pairs in contact. The detailed analysis showed that case 1, case 2 and case 3 load cases overestimate the SIFs comparing to the case 4. The first three load cases overestimate the KI by 39%, 2.5%, and 45% and KII by 390%, 36%, and 129% and KIII by 282%, 47%, and 132% respectively when compared to load case 4. The results of this study provide valuable guidelines for the crack propagation as well as life prediction calculations for spur gear drives.

A Study on the Load Distribution Ratio and Axial Stiffness on Existing and Reinforcing-Pile in Vertical Extension Remodeling

A Study on the Load Distribution Ratio and Axial Stiffness on Existing and Reinforcing-Pile in Vertical Extension Remodeling

Seismic Performance Evaluation of Steel Moment Frame Factory Building with Slender Braces

'Seismic Performance Evaluation Method for Existing Buildings (2013)' developed in accordance with the overseas guidelines ASCE 41 - 06 is the most widely used procedure among domestic seismic performance evaluation guidelines in Korea. However, unlike ASCE 41 - 06, it stipulates that the final performance should be derived as the gravity load distribution ratio of the lateral force resistance system in the guideline. Therefore, in the case of a dual steel structure system with slender braces, where the internal moment frame is mostly responsible for the gravity load, the evaluation of slender braces based on gravity load distribution ratio is difficult to be achieved. In this research, we propose an objective evaluation process for such system by evaluating seismic performance for large-scale factory facilities as an example.

Measurement of the Moment of Inertia for a Zero Turning Radius Mower

<abstract> The moment of inertia (MI) is one of the important factors that affect the continuous roll behavior of a zero turning radius (ZTR) mower, and therefore, an accurate measurement or calculation of the MI is required. Previous research focused on the estimation techniques for vehicle MIs, and the measurements included a car, pickup truck, sport utility vehicle, and van, all of which have a small front/rear axle load distribution difference (i.e., the front/rear axle load distribution ratio ranges from 0.67 to 1). However, little research has investigated the MI of a ZTR mower, which has a large front/rear axle load distribution difference (i.e., the front/rear axle load distribution ratio is approximately 0.33); thus, the load distribution of a ZTR mower is more nonhomogeneous than that of the other vehicles. The primary objectives of this research were to investigate a mathematical model and a suitable MI measurement method for the ZTR mower, which is a difference in front/rear axle load distribution. A mathematical model was developed based on the principle of the pendulum method for measuring the MI in the x-, y-, and z-axes. Three ZTR mowers were used as test vehicles: a mower without a deck, a 1.2 m swath mower, and a 1.8 m swath mower. The test results were compared with the results obtained using the empirical formulas. Based on the comparison of the MIs, the results of the tests were within the range of 6.7% to 16.5% of the relative error from the values calculated using the empirical formulas. The test results indicated that the relative errors increased for mowers with a large difference in the front/rear axle load distribution.

Strut-tie model for two-span continuous RC deep beams

In this study, a simple indeterminate strut-tie model which reflects complicated characteristics of the ultimate structural behavior of continuous reinforced concrete deep beams was proposed. In addition, the load distribution ratio, defined as the fraction of applied load transferred by a vertical tie of truss load transfer mechanism, was proposed to help structural designers perform the analysis and design of continuous reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of the load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie was introduced to ensure the ductile shear failure of reinforced concrete deep beams, and the primary design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete were reflected upon. To verify the appropriateness of the present study, the ultimate strength of 58 continuous reinforced concrete deep beams tested to shear failure was evaluated by the ACI 318M-11\'s strut-tie model approach associated with the presented indeterminate strut-tie model and load distribution ratio. The ultimate strength of the continuous deep beams was also estimated by the experimental shear equations, conventional design codes that were based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the proposed strut-tie model and load distribution ratio was examined through the comparison of the strength analysis results classified according to the primary design variables. The present study associated with the indeterminate strut-tie model and load distribution ratio evaluated the ultimate strength of the continuous deep beams fairly well compared with those by other approaches. In addition, the present approach reflected the effects of the primary design variables on the ultimate strength of the continuous deep beams consistently and reasonably. The present study may provide an opportunity to help structural designers conduct the rational and practical strut-tie model design of continuous deep beams.

프리스트레스트 콘크리트 보의 부정정 스트럿-타이 모델

이 논문에서는 스트럿-타이 모델을 이용한 프리스트레스트 콘크리트 보의 해석 및 설계 시 프리스트레스트 콘크리트 보의 비선형 파괴거동 특성 및 복잡한 하중전달 메커니즘을 합리적인 방법으로 반영할 수 있는 단순한 형태의 부정정 스트럿-타이 모델을 제안하였다. 또한 현행 설계기준서의 스트럿-타이 모델 규정을 이 연구에서 제안한 부정정 스트럿-타이 모델에 접목시켜 프리스트레스트 콘크리트 보의 해석 및 설계를 수행할 수 있는 부정정 스트럿-타이 모델의 하중분배율을 제안하였다. 이 연구에서 제안한 부정정 스트럿-타이 모델 및 하중분배율의 적합성을 검증하기 위해 파괴실험이 수행된 47개의 프리스트레스트 콘크리트 보의 극한강도를 평가하였으며, 그 결과를 현행 설계기준서의 스트럿-타이 모델 방법에 의한 평가결과와 비교분석 하였다. In this study, a statically simple indeterminate strut-tie model is proposed for the rational analysis and design of simply supported prestressed concrete beams by reflecting all characteristics of nonlinear structural behavior and load transfer mechanisms. In addition, a load distribution ratio that allows to transform the proposed indeterminate strut-tie model to a determinate model is also suggested to help structural designers conduct the structural analysis and design of simply supported prestressed concrete beams by using the strut-tie model method of current design codes. For verifying of the validity of the proposed model and load distribution ratio, the ultimate strengths of 47 simply supported prestressted concrete beams tested to failure were estimated and the results were compared with those by the strut-tie model methods of current design codes.

기존말뚝과 보강말뚝의 하중분담 특성에 관한 실험적 연구

최근 공동주택 수직증축 리모델링 사업 등 기초구조물을 보강하기 위한 기술적 수요가 증가하고 있다. 본 논문에서는 기존 구조물을 지지하는 기존말뚝에 보강말뚝을 추가로 설치할 경우 추가하중에 의한 기존말뚝과 보강말뚝의 하중분담 특성을 연구하였다. 정사각형의 기초판에 설치된 기존말뚝 4본에 허용하중을 재하한 후, 기초판 중앙에 보강말뚝 1본을 추가로 설치하고 추가하중을 재하하였다. 실험결과로부터 기존말뚝에 재하되는 하중이 허용지지력을 초과한 이후에 기존말뚝과 보강말뚝이 하중을 균등하게 분담하는 것으로 분석되었다. 기존말뚝에 허용하중 재하 후, 허용하중 대비 60 %, 80 %, 100 %까지 제하(unloading)하고, 보강말뚝을 설치한 후 추가하중을 재재하(reloading)하는 실험을 수행하였다. 연구 결과 제하 하중의 양이 증가함에 따라 재재하 시 기존말뚝과 보강말뚝이 하중을 균등하게 분담하는 재재하 하중이 감소하는 경향을 파악하였다. Recently, there are increasing technical needs for foundation retrofit project such as vertical extension of apartment building. This paper focuses on the load distribution characteristics of existing and reinforcing piles when reinforcing pile is installed to the existing foundation. Allowable bearing load was initially applied on the foundation slab supported with four existing piles and then, one reinforcing pile was installed at the center of foundation slab and additional load was applied. The experimental results showed the Load Distribution Ratio (LDR) between existing and reinforcing piles converged after the applied load exceeded allowable bearing capacity of all piles. Laboratory tests were also performed for the cases of 60 %, 80 %, 100 % unloading level of allowable bearing load. After unloading step, one reinforcing pile was installed at the center of foundation slab and additional load was applied. The results showed that reloading load level at which LDR between existing and reinforcing piles converged decreased as the amount of unloading load increased.

Avoiding Energy Holes Problem using Load Balancing Approach in Wireless Sensor Network

Clustering wireless sensor network is an efficient way to reduce the energy consumption of individual nodes in a cluster. In clustering, multihop routing techniques increase the load of the Cluster head near the sink. This unbalanced load on the Cluster head increases its energy consumption, thereby Cluster heads die faster and create an energy hole problem. In this paper, we propose an Energy Balancing Cluster Head (EBCH) in wireless sensor network. At First, we balance the intra cluster load among the cluster heads, which results in nonuniform distribution of nodes over an unequal cluster size. The load received by the Cluster head in the cluster distributes their traffic towards direct and multihop transmission based on the load distribution ratio. Also, we balance the energy consumption among the cluster heads to design an optimum load distribution ratio. Simulation result shows that this approach guarantees to increase the network lifetime, thereby balancing cluster head energy.

An Indeterminate Strut-Tie Model and Load Distribution Ratio for Reinforced Concrete Corbels

철근콘크리트 코벨의 파괴거동은 코벨의 전단경간비 및 주인장 철근비를 포함한 여러 변수들로 인해 복잡하다. 이 논문에서는 철근콘크리트 코벨의 강도 및 거동 특성을 논리적이고 합리적인 방법으로 반영하여 전단경간비가 1.0 이하인 철근콘크리트 코벨을 설계할 수 있는 단순한 형태의 1차 부정정 트러스 구조의 스트럿-타이 모델을 제안하였다. 또한 부정정 스트럿-타이 모델을 정정 트러스 구조의 스트럿-타이 모델로 변환시켜 현행 스트럿-타이 모델 설계기준에 의한 코벨의 설계를 가능하게 하는 하중분배율을 제안하였다. 하중분배율 결정 시 스트럿과 타이의 재료적 비선형 거동을 고려할 수 있는 부정정 스트럿-타이 모델의 비탄성 구조해석을 통해 철근콘크리트 코벨의 강도 및 거동을 지배하는 전단경간비, 주인장 철근비, 수직하중에 대한 수평하중의 비, 그리고 콘크리트의 압축강도 등의 주요설계변수들의 영향을 반영하였다. 이 연구에서 제안한 부정정 스트럿-타이 모델 및 하중분배율의 적합성을 검증하기 위해 파괴실험이 수행된 다수의 철근콘크리트 코벨의 극한강도를 평가하였으며, 그 결과를 ACI 318-11의 전통적인 설계기준 및 정정 트러스 구조의 스트럿-타이 모델을 기반으로 하는 현행 주요 설계기준의 스트럿-타이모델 방법에 의한 평가결과와 비교분석하였다. The ultimate behavior of reinforced concrete corbel is complicated due to the primary design variables including the shear span-to-effective depth ratio a/d, flexural reinforcement ratio, load condition, and material properties. In this study, a simple indeterminate strut-tie model reflecting all characteristics of the ultimate strength and complicated structural behavior is proposed for the design of the reinforced concrete corbels with shear span-to-effective depth ratio of <TEX>$a/d{\leq}1$</TEX>. A load distribution ratio, defined as the fraction of applied load transferred by horizontal truss mechanism, is also proposed to help structural designers perform the design of reinforced concrete corbels by using the strut-tie model approaches of current design codes. For the development of the load distribution ratio, numerous material nonlinear finite element analyses of the proposed indeterminate strut-tie model were conducted by changing primary design variables. The ultimate strengths of reinforced concrete corbels tested to failure were evaluated by incorporating the proposed strut-tie model and load distribution ratio into the ACI 318-11's strut-tie model method. The validity of the proposed model and load distribution ratio was examined by comparing the strength analysis results with those by the ACI 318-11's conventional design method and strut-tie model methods of current design codes.

Energy Consumption Modelling for Air-Cushion Vehicles

Air-cushion vehicles (ACVs) provide a solution to transportation on soft terrain, whereas they also bring a new problem of excessive energy consumption to be solved. The prerequisite for energy consumption optimization is its modelling and simplification with respect to vehicle independent operating parameters. In a scenario of steady-state longitudinal drive condition, by employing slip ratio and load distribution ratio as independent parameters, dependent parameters and energy consumption are inferred and finally expressed as functions of the independent parameters. The method and result can be taken reference by studies of energy consumption modelling for air-cushion vehicles in different structures and also extensively for common electric vehicles.

Progressive collapse analysis of steel truss bridges and evaluation of ductility

Deteriorated steel truss bridges have caused catastrophes in the USA and Japan. Progressive collapse analysis is carried out for three continuous steel truss bridge models with a total length of 230.0m using large deformation and elastic plastic analysis. The analysis is to clarify how the live load intensity and distribution affect ultimate strength and ductility of two steel truss bridge models, Bridge Model A with a span ratio of 1:2:1 and Bridge Model B with a span ratio of 1:1.3:1. Sizes and steel grades of the truss members are determined so that they are within the allowable stress for the design dead and live loads. After the design load is applied, the live load is increased until the bridge model collapses. Although the collapse process differs depending on live load distribution and span length ratio, both steel truss bridge models collapse due to buckling of compression members. When the live load is fully applied in the center span, the span ratio does not affect the ultimate strength which is sufficiently high and the model bridge is safe. When the live load is applied in the side span, the model bridge with a longer side span has higher ultimate strength. When the live load is applied near the intermediate support, the model bridge with a longer center span has higher ultimate strength. As for the ductility factor which is defined by the ultimate load over the yield load, Bridge Model B is in general more ductile than Bridge Model A. This leads to the fact that the center and side span length ratio of Bridge Model B with more commonly used dimensions is rational. This study clarifies the collapse process, buckling strength, and influences of live load distribution and the span ratio on a steel truss bridge.

Interference-Aware Bandwidth Reservation in multi-radio multi-channel mesh networks

In this paper, we propose the Interference-Aware Bandwidth Reservation (IABR) scheme for providing flow admission control and bandwidth reservation for end-to-end flows in 802.11 multi-radio multi-channel wireless mesh networks. The effects of inter-flow and intra-flow interference have often been neglected in existing solutions, which can lead to inaccurate bandwidth estimation and reservation. IABR models both the current inter-flow interference from existing flows and the expected intra-flow interference of the incoming flow to make accurate estimation of the available bandwidth and perform admission control. Moreover, IABR exploits wireless link diversity between neighboring nodes in multi-radio multi-channel mesh networks to improve flow admission ratio and ensure efficient load-balancing. Simulation results show that IABR provides accurate bandwidth estimation, excellent load distribution and high flow admission ratio.

An Indeterminate Strut-Tie Model and Load Distribution Ratio for RC Deep Beams - (I) Model &amp; Load Distribution Ratio

The ultimate strength of simply supported reinforced concrete deep beams is governed by the capacity of the shear resistance mechanism. The structural behavior of the deep beams is controlled mainly by the mechanical relationships between the primary design variables including shear span-to-effective depth ratio, flexural reinforcement ratio, and the compressive strength of concrete. In this study, a simple indeterminate strut-tie model which reflects all characteristics of the ultimate strength and behavior of the deep beams was presented. A load distribution ratio, defined as the fraction of load transferred by a truss mechanism, was also proposed to help structural designers perform the rational design of deep beams by using the strut-tie model approaches of current design codes. In the determination of the load distribution ratio, a concept of balanced shear reinforcement ratio which ensures the ductile shear design of the deep beams was introduced, and the effect of the primary design variables was reflected through numerous numerical analyses of the presented indeterminate strut-tie model. In the companion paper, the validity of the presented model and load distribution ratio was examined by applying them to the evaluation of ultimate strength of 234 simply supported reinforced concrete deep beams tested to failure.

An Indeterminate Strut-Tie Model and Load Distribution Ratio for RC Deep Beams- (II) Validity Evaluation

In this study, the ultimate strength of 234 simply supported reinforced concrete deep beams tested to shear failure was evaluated by the ACI 318M-08's strut-tie model approach implemented with the indeterminate strut-tie model and load distribution ratio of the companion paper. The ultimate strength of the deep beams was also estimated by using the experimental shear strength models, the theoretical shear strength models, and the current strut-tie model design codes. The validity of the presented indeterminate 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 compressive strength of concrete. The present study associated with the indeterminate strut-tie model and load distribution ratio evaluated the ultimate strength of 234 deep beams fairly accurately compared with those by other approaches. In addition, the present approach reflected the effects of the primary design variables on the ultimate strength of deep beams consistently and accurately.

Dynamic Modeling of Intelligent Air-Cushion Tracked Vehicle for Swamp Peat

Modeling of the dynamic behavior and motion are renewed interest in the improved tractive performance of an intelligent air-cushion tracked vehicle (IACTV). This paper presents a new dynamical model for the forces on the developed small scale intelligent air-cushion tracked vehicle moving over swamp peat. The air cushion system partially supports the 25 % of vehicle total weight in order to make the vehicle ground contact pressure 7 kN/m2. As the air-cushion support system can adjust automatically on the terrain, so the vehicle can move over the terrain without any risks. The springdamper system is used with the vehicle body to control the aircushion support system on any undulating terrain by making the system sinusoidal form. Experiments have been carried out to investigate the relationships among tractive efficiency, slippage, traction coefficient, load distribution ratio, tractive effort, motion resistance and power consumption in given terrain conditions. Experiment and simulation results show that air-cushion system improves the vehicle performance by keeping traction coefficient of 71% and tractive efficiency of 62% and the developed model can meet the demand of transport efficiency with the optimal power consumption.

연속지지 RC 깊은 보의 부정정 스트럿-타이 모델 및 하중분배율 (I) 모델 및 하중분배율의 제안

The structural behavior of continuous reinforced concrete deep beams is mainly controlled by the mechanical relationships associated with the shear span-to-effective depth ratio, flexural reinforcement ratio, load and support conditions, and material properties. In this study, a simple indeterminate strut-tie model which reflects characteristics of the complicated structural behavior of the continuous deep beams is presented. In addition, the reaction and load distribution ratios defined as the fraction of load carried by an exterior support of continuous deep beam and the fraction of load transferred by a vertical truss mechanism, respectively, are proposed to help structural designers for the analysis and design of continuous reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of the load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie is introduced to ensure a ductile shear failure of reinforced concrete deep beams, and the primary design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and concrete compressive strength are implemented after thorough parametric numerical analyses. In the companion paper, the validity of the presented model and load distribution ratio was examined by applying them in the evaluation of the ultimate strength of multiple continuous reinforced concrete deep beams, which were tested to failure.