Influence Of Vertical Load Research Articles

Influence of Vertical Load, Inflation Pressure, and Driving Speed on the Emission of Tire–Road Particulate Matter and Its Size Distribution

As fleet electrification progresses, vehicles are continuously becoming heavier, while the used electric motors, with their high torques, enable longitudinal dynamics to be maintained or even increased. This raises the question of what effect electric vehicles have on the emission of tire–road particulate matter (PM). To answer this question, investigations were carried out in this study on a tire internal drum test bench with real road surfaces. In addition to the vertical load, the tire inflation pressure and the driving speed were varied. PM emissions were recorded in real time, resulting in emission factors (emission per kilometer driven) for different load conditions. This allows statements to be made about both the effect on the total emission and on the particle size distribution. It was shown that the PM emission increases linearly with the vertical load at constant longitudinal dynamics. If the tire inflation pressure is increased, the emission also increases linearly, and the increases in emission are equally large for both influences. A clear influence of the driving speed on the emission factor could not be determined. With regard to the particle size distribution, the following correlations were found: higher vertical load and higher tire inflation pressure result in a larger mean particle diameter, while a higher driving speed reduces it. Thus, this study contributes to a better understanding of the expected changes in tire-road PM emissions as a result of electrification.

Experimental studies on the response of single-finned pile under combined vertical-torsional loads in sand

ABSTRACT Pile foundations may be exposed to torsional loads caused by horizontal eccentric loads brought on waves, wind and earthquakes, as well as axial load brought on by supporting superstructures. This paper highlights a recent strategy to modify piles known as the finned pile. A series of experimental tests were conducted to increase the torsional capacity of a single pile with/without fins in sand under the influence of vertical loads (V), torsional loads (T) and combined loads (T → V), these experiments involved altering fins’ length, width, shape, and number and knowing the effect of these variables on the piles’ maximum torsional capacity. The vertical load-displacement response and the torsion-rotation response have been observed. The results showed that fins improve piles’ torsional capacity. It also showed that on piles’ maximum vertical capacity for independent vertical or torsional loads is different from that of piles under combined loading. It was found that fins’ optimum geometry is that their length equal to 0.6 of the embedded pile’s length and their width equal to the pile’s diameter, where piles’ maximum torsional capacity was (4.12 and 7.36) N.m for regular and finned piles, respectively. Fins increased piles’ maximum torsional capacity by about 79%.

Influence of Vertical Load on the Lateral Response of Piles in Normally Consolidated and Over-Consolidated Clay: Centrifuge and Numerical Modelling

Although pile foundations are usually subjected to both lateral and vertical loads, there have been few studies on the pile response under the combined loadings. Moreover, those few studies led to inconsistent conclusions concerning the influence of vertical load on the lateral pile response. This study aims to investigate the effect of vertical load on the monotonic and cyclic lateral response of piles in normally consolidated (NC) and over-consolidated (OC) clay through a series of centrifuge tests. Three-dimensional finite element analyses using an advanced hypoplastic clay model were also performed to gain deep insight into the mechanism. It is revealed that after applying the vertical load and allowing the dissipation of the induced excess pore pressure, the lateral initial stiffness and ultimate capacity of the pile in the NC clay increased by 10.0 and 49.4%, respectively. However, in the OC clay, the application of the vertical load resulted in a 12.6 and 32.4% reduction in the lateral pile initial stiffness and ultimate capacity, respectively, showing a distinct response from that in the NC clay. The above-mentioned distinct influence of vertical load for piles can be attributed to the different evolutions of stress ratio (q/p’) of the soil around the pile in the NC and OC clay, which determines the soil mobilisable shear strength and consequently the lateral pile responses.

Unidirectional Geosynthetic Reinforcement Design for Bridging Localized Sinkholes in Transport Embankments

The durability of foundations with localized sinkholes can be improved by geosynthetic-reinforced soil. Current design methods for geosynthetic-reinforced structures are based on the assumptions that the vertical load is distributed uniformly on the geosynthetic above the sinkhole and it corresponds to the geostatic stress in the anchorage area. In this study, a new analytical method is proposed to consider the ‘secondary arching effect’ and the vertical load distribution in the anchorage area due to the ‘arching effect.’ The influence of vertical load acting on the geosynthetic is analyzed based on three different cases. Results indicate that the increment of vertical load on the geosynthetic in the anchorage area has little effect on the maximum tensile force and surface settlement. Compared to a uniform load distribution on the geosynthetic above the sinkhole, the assumption of an inverse triangular load distribution can reduce the maximum tensile force and surface settlement. A new design method is proposed to determine the minimum geosynthetic stiffness to meet design standards. The obtained results verify the method as an applicable tool to meet the serviceability limit state and the ultimate limit state criteria.

A numerical technique for modeling the behavior of single piles in unsaturated soils

Pile foundations are widely used in both saturated and unsaturated soils. In certain scenarios, these foundations are subjected to combined vertical and lateral loads. Conventionally, saturated soil mechanics principles are routinely used for the design of pile foundations in unsaturated soils. Such approaches contribute to unreliable estimates of the behavior of piles due to ignoring the influence of matric suction. In this paper, a comprehensive numerical technique is proposed for simulating the behavior of single piles subjected to combined vertical and lateral loads in unsaturated soils by taking account of the nonlinear behavior of shear strength and the elastic modulus of unsaturated soils. This is achieved through a subroutine that was developed for use in the ABAQUS software. The proposed numerical method provided reliable prediction of the vertical load-displacement behavior of a published model pile tested in saturated and unsaturated sands. In addition, 3D finite element analysis was extended to simulate the influence of variations in ground water table (GWT) on the vertical bearing capacity and the influence of vertical loads on lateral response of piles. The proposed numerical technique is a promising tool for implementing the state-of-the-art understanding of the mechanics of unsaturated soils into conventional engineering practice.

Assessment of out-of-plane strength of masonry infills through a FE augmented dataset

Evaluation of the out-of-plane strength of infilled frames is a matter of fundamental importance. In fact, by observing post-earthquake damage, it has been noted that infills subject to in-plane and out-of-plane inertial forces may achieve collapse due to out-of-plane actions. This mode of collapse may result quite dangerous to the people in the proximity of a building subjected an earthquake. The possibility to perform an accurate safety assessment is fundamental to prevent this type of failure. Different expressions for evaluating the out-of-plane resistance of infilled frames are available in the literature. These are based on analytical formulations validated on the basis of too limited or too large experimental datasets. This implies that these expressions are often conflicting, showing good reliability in some cases and less in others. In order to overcome this drawback, this paper provides the definition of a hybrid database obtained by merging existing experimental test data with additional ones obtained from numerical simulations by means of a refined FE micro-model. A new data-driven empirical expression for estimating the OOP resistance of infilled frames has been developed based on the hybrid database so developed. The new expression has the advantage of taking into account the aspect ratio of the filled frame, the influence of vertical loads, and the influence of the out-of-plane load application mode. Finally, validation tests are performed against experimental and numerical samples.

Research on dual-wheel-independent-drive control of electric forklift based on optimal slip ratio.

As an important transportation, the research on the control strategy of forklift has not been widely carried out. This article proposes a turning slip regulation control strategy, which includes the improved electronic differential velocity control and turning slip regulation control, to track the optimal slip ratio. First, combined with the basic structure and characteristics of dual-wheel-independent-drive electric forklift, the vehicle model, Ackermann-Jeantand steering model, tire-ground model, and tire model of the driving wheel are established respectively. Second, according to these models, an improved electronic differential control strategy considering the influence of vertical load on tire force is proposed and it can reasonably allocate the driving torque of the two driving wheels of electric forklift. Moreover, the optimal slip ratio is given out and the turning slip regulation control strategy, which can track the optimal slip ratio of electric forklift under the conditions of different road surfaces is designed. The simulation result and vehicle test show that the control strategy can optimize the slip ratio of electric forklift and greatly improve the stability of electric forklift. The turning slip regulation control strategy can be implemented on the TFC35 forklift to improve the safety and stability.

A Review on Interaction Effect of Pile under Vertical Compression

The present theories and methods for design of the vertically loaded pile foundations generally provides the overall values of bearing capacity and settlement characteristics for the pile groups. In every design criteria for vertically loaded pile system, there are some factors affecting on major scale such as bearing capacity, Settlement, skin friction etc. This review paper shows that the consequences of vertical load on pile foundation done by various researchers and from their results help in predicting the load–settlement behavior of vertically loaded pile and pile groups. It is observed, when the group efficiency is close to unity, the variation between expected and observed behavior of piles proves to be a positive approach towards the ultimate load. Hence, various researchers have tested and published their laboratory and theoretical values on load-settlement characteristics under the influence of vertical load on pile foundation. This paper illustrates about comparison of various test results and their research gap on consequences of vertically loaded pile foundation.

Comparative Analysis of Static Loading Performance of Rigid and Flexible Road Wheel based on Finite Element Method

To overcome the shortcomings of traditional rigid road wheel, such as poor damping effect and low load-bearing efficiency, a new type of flexible road wheel, having a unique suspension-bearing mode, was introduced. The three-dimensional nonlinear finite element model of rigid and flexible road wheel, considering the triple nonlinear characteristics of geometry, material and contact, is established for numerical investigation of static loading performance. The accuracy of the finite element model of the rigid and flexible road wheel is verified by static loading experiment. The static loading performance of the rigid and flexible road wheels is numerically analyzed. The influence of vertical load on maximum stress and deformation of the rigid and flexible wheels is also studied. The results show that the contact pressure uniformity of the flexible road wheel is better than that of the rigid road wheel under the static vertical load, but the maximum stress and deformation of the flexible road wheel are greater than that of the rigid road wheel. However, this problem can be solved by increasing the number of hinge sets and optimising the joints. The research results provide theoretical basis for replacing rigid road wheel with flexible road wheel, and also provide reference for structural optimisation of flexible road wheel.

The Effect of Vertical Loads and the Pile Shape on Pile Group Response under Lateral Two-Way Cyclic Loading

This paper is presented the lateral dynamic response of pile groups embedded in dry sand under influence of vertical loads and the pile shape in-group, which are subjected to the lateral two-way cyclic loads. The laboratory typical tests with pile groups (2×1) have an aluminum-pipe (i.e. circular, square) pile, embedded length to diameter of pile ratio (L/D=40) and spacing to diameter ratio (S/D) of 3, 5, 7 and 9 are used with different cyclic-load ratio (CLR) 0.4, 0.6 and 0.8. The experimental results are revealed that both the vertical and lateral pile capacity and displacement is significantly affected by the cyclic-loading factors i.e. (number of cycles, cyclic load ratio, and shape of pile) .In this study, important design references are presented. Which are explained that the response of the pile groups under cyclic lateral loading are clear affected by the attendance of vertical load and pile shape. Where, it is reduction the lateral displacement of group piles head and increase lateral capacity about (50) % compared without vertical loads. On the other side, the pile shape is a well affected to the pile response where the level of decline in lateral displacement at the pile groups head in the square pile is more than circular pile about 20 % at the same load intensity.

INFLUENCE OF VERTICAL LOAD ON BRAKING FORCE AND TYRE ADHESION COEFFICIENT OF VEHICLE WHEEL

Influence of vertical load on the adhesion coefficient of automobile wheel in the braking mode on the basis of experimental researches is analyzed. Research results of different authors concerning the degree of the influence of various factors on the adhesion coefficient are presented. It is known that the fundamental basis of vehicle active safety is its braking properties, and the nature of braking depends on the interaction of motorcar tires with road surfaces. Such interaction in the theory of a car is usually described by the adhesion coefficient, which can be implemented both in the longitudinal and transverse directions relative to the rotation area of the vehicle wheels. Experimental researches on rolling car wheel of locking border have demonstrated that a high change of filling speed of the brake chamber does not contribute to increasing the braking efficiency and consequently, the work of the modulator in the mode of intensive filling of brake chamber makes no sense. Vice versa, as experimental researches have demonstrated, the reduction of filling rate of the brake chamber increases the efficiency of braking, although at the initial moment of time, due to the low braking torque, the efficiency is slightly underestimated. Considering the inconsistency of the adhesion coefficient in automotive practice will allow modeling dynamics of vehicle inhibition with automatic regulation systems at a higher level and with greater reliability. Increasing the vehicle mass leads to a decrease in the coupling properties of its tires and consequently to reduce the amount of deceleration, reducing its mass, vice versa increases the coupling properties between the tire and support surface, which positively affects the performance of the vehicle braking (its slowing increases).

Key parameters influencing performance and failure modes for interaction soil–pile–structure system under lateral loading

The behavior of the interaction soil–pile–structure under lateral loads is a topic not fully investigated in the literature. However, soil–pile–superstructure interaction largely affects the design forces in columns and piles. In contrast, fixed base assumption cannot capture soil structure interaction effect. In this study, the effects of the lateral capacity of interaction soil–pile–structure (ISPS) system under lateral loads have been investigated. The lateral capacity of ISPS system can be obtained by pushover analysis. The influence of vertical loads, pile diameter, longitudinal steel ratio, length of pile and type of soil on the lateral response of piles installed in three types of sandy soil are brought out in this paper through nonlinear static analysis and pile behavior in these conditions is investigated and characterized via: lateral capacity, spectral capacity, performance point, position of plastic hinge, over-strength factor, ductility and the response modification factors. The results indicate that the lateral capacity and spectral capacity are affected.

Study on mechanical behaviors of column foot joint in traditional timber structure

Column is usually floating on the stone base directly with or without positioning tenon in traditional Chinese timber structure. Vertical load originated by the heavy upper structure would induce large friction force and compression force between interfaces of column foot and stone base. This study focused on the mechanical behaviors of column foot joint with consideration of the influence of vertical load. Mechanism of column rocking and stress state of column foot has been explored by theoretical analysis. A nonlinear finite element model of column foot joint has been built and verified using the full-scale test. The verified model is then used to investigate the mechanical behaviors of the joint subjected to cyclic loading with different static vertical loads. Column rocking mechanism and stress distributions of column foot were studied in detail, showing good agreement with the theoretical analysis. Mechanical behaviors of column foot joint and the effects of the vertical load on the seismic behavior of column foot were studied. Result showed that compression stress, restoring moment and stiffness increased with the increase of vertical load. An appropriate vertical load originated by the heavy upper structure would produce certain restoring moment and reset the rocking columns, ensuring the stability of the whole frame.

Influence of Vertical Loads on Quasi-constant Rotational Stiffness of The Cross-spring Flexure Pivot

Influence of Vertical Loads on Quasi-constant Rotational Stiffness of The Cross-spring Flexure Pivot

Influence of vertical loads on lateral behaviour of monopiles in sand

The monopiles are always subjected to both vertical loads and lateral loads. However, the designs for the piles under the vertical loads and the lateral loads are carried out separately in practice because the interaction between those two loads is still unclear. A series of model tests are carried out to investigate the influence of the vertical loads on the lateral responses of the monopile in sandy soil. The results show that the presence of the vertical load improves the lateral behaviour of the monopile. The influence of the vertical load on p–y curve around the monopile is also investigated to look for a useful suggestion for the design of monopile. In order to calculate the lateral responses of the monopile based on traditional design method, several equations are proposed to evaluate the degree of improvements.

Influence of vertical load on in-plane behavior of masonry infilled steel frames

Results of an experimental program are presented in this paper for the influence of vertical load on the in-plane behavior of masonry infilled steel frames. Five half-scaled single-story, single-bay steel frame specimens were tested under cyclic lateral loading. The specimens included four infilled frames and one bare frame. Two similar specimens as well as the bare frame had moment-resisting steel frames, while the remaining two specimens had pinned steel frames. For each frame type, one specimen was tested under simultaneous vertical and lateral loading, whereas the other was subjected only to lateral loading. The experimental results show that the vertical load changes the cracking patterns and failure modes of the infill panels. It improves dissipated hysteresis energy and equivalent viscous damping. Global responses of specimens, including stiffness and maximum strength, do no change by vertical loading considerably. Regarding the ductility, the presence of vertical load is ignorable in the specimen with moment-resisting frame. However, it increases the ductility of the infilled pinned frame specimen, leading to an enhancement in the m-factor by at least 2.5 times. In summary, it is concluded that the influence of the vertical load on the lateral response of infilled frames can be conservatively ignored.

Numerical investigation of the lateral response of battered pile foundations

Three-dimensional finite difference parametric analyses have been carried out to investigate the influence of vertical loads on the lateral performance of battered piles in both sandy and clayey soils. Different batter angles and soil stiffness were considered to examine the salient features of this complex soil–structure interaction problem. Numerical results show that the lateral response of battered piles embedded in sands is influenced by the value and the direction of the pile inclination, the presence of vertical loads as well as the soil state of density. When the lateral load acts in the opposite direction of the pile inclination (negative batter angle), the lateral response of the piles increases substantially with the batter angle as well as the sand packing. The response of piles at positive batter angles, however, does not appear to vary considerably with the batter angle or the sand density. The effect of the vertical loads on lateral response of battered piles in sands is found to be very pronounced. On the other hand, the lateral response of piles embedded in a clayey soil at negative batter angles increases greatly with the inclination angle and does not vary with its undrained shear strength. The lateral response of the piles with positive inclination angles is independent of the batter angle and the soil stiffness. Moreover, the presence of a vertical load prior to the application of a lateral load to a battered pile does not alter its lateral capacity.

Seismic analysis of laterally loaded pile under influence of vertical loading using finite element method

An efficient analytical approach using the finite element (FE) method, is proposed to calculate the bending moment and deflection response of a single pile under the combined influence of lateral and axial compressive loading during an earthquake, in both saturated and dry homogenous soil, and in a typical layered soil. Applying a pseudo-static method, seismic loads are calculated using the maximum horizontal acceleration (MHA) obtained from a seismic ground response analysis and a lateral load coefficient (a) for both liquefying and non-liquefying soils. It is observed that for a pile having l/d ratio 40 and embedded in dry dense sand, the normalized moment and displacement increase when the input motion becomes more severe, as expected. Further increasing of a from 0.1 to 0.3 leads to increase in the normalized moment and displacement from 0.033 to 0.042, and 0.009 to 0.035, respectively. The validity of the proposed FE based solution for estimating seismic response of pile is also assessed through dynamic centrifuge test results.

On the influence of vertical loads on the lateral response of pile foundation

The influence of vertical loads on the lateral response of group piles installed in sandy soil and connected together by a concrete cap is studied through finite elements analyses. The analyses focus on the five piles in the middle row of 3×5 pile groups. The vertical load is applied by enforcing a vertical displacement equivalent to 2% of the pile diameter through the pile cap prior to the application of the lateral loads. The results have shown that the lateral resistance of the leading pile (pile 1) does not appear to vary considerably with the vertical load. However, the vertical load leads to 23%, 36%, 64%, and 82% increase in the lateral resistance of piles 2–5, respectively. The increase in the lateral pressures in the sand deposit is the major driving factor to contribute the change in the lateral resistance of piles, depending on the position of the pile in the group. The distribution of lateral loads among piles in the group tends to be more uniform when vertical loads were considered leading to a more economical pile foundation design.

The Influence of Vertical Loads on Lateral Deformation of Steel Reinforced Concrete Column

The influence of vertical loads on steel reinforced concrete column is analyzed, based on the maximum lateral displacement of 2 different steel reinforced concrete columns under different vertical loads. The vertical loads, the section properties of the steel reinforced concrete column and horizontal loads are the influencing factors.