Long-Term Performance of Jointed Plain Concrete Pavement with Rapid Strength Concrete On California Highways

Rapid Strength Concrete (RSC) slabs on six California jointed plain concrete pavement (JPCP) highway projects were surveyed. These projects had been previously surveyed in 2008 at 3-years of age and by 2018 had reached a service life of 13-years. Of the initial 5430 slabs examined in 2008, a total of 1493 RSC slabs, located on 12 traffic lanes, were observed and distress types recorded again in 2018. These slabs included both CTS and 4x4 RSC located in both inner and outer lanes. Only a small percentage (1.4%) of the 5,430 RSC slabs exhibited any distress in 2008 after 3-years' service and the increases were small over the next 10 years of service with the exception of transverse fatigue cracks. The transverse (top down fatigue) type of cracking had the highest percentage and largest increase of any distress type. The heavy truck outside lanes exhibited 21% transversely cracked RSC slabs and the inner passing lanes 3%. The outer truck lanes carried over 3 times more trucks than inner lanes. The RSC slabs were mostly 200-223 mm thick and thus susceptible to fatigue damage. The overall performance of the RSC slabs (both CTS and 4x4 RSC materials) were similar and considered to be outstanding over 13 years with a large majority expected to survive many more years.

Video Image Correlation-Based Method Used for the Study of the Torsional Vibrations of an Adder Gearbox

In this paper, a study of the vibrations that appear in the transmission shafts of an adder gearbox used for a heavy truck is made. The truck has two engines on only one chassis and the power offered by these engines is summated and transmitted to the truck or the working machine. This type of transmission is used for oil production installation for the army. During the transportation of the installation to the workplace, only one engine is running, after mounting installation, both engines are running. This paper studies the vibrations of the adder gearbox, a complex construction, subjected to multiple operating requirements. In this regard, the authors first performed accuracy (accuracy) tests of the VIC 3D system on an original experimental mini-stand. Measurements performed on a mini disc demonstrated the validity and accuracy of the method, even if the cameras used were not high resolution. The authors applied the same principle in the case of the adder box from the truck, obtaining useful results for those in the field. The experimental method uses the facilities of a contactless optical measurement method (VIC-3D), which provides a high-accuracy quantitative linear and angular vibration analysis. The VIC measurement method offers, based on a frontal viewing of the disk during the resonance phenomenon and by simple calculus on the monitored linear displacements, the corresponding angular amplitude.

Development of heavy truck models and their effects on girder bridges

The traffic on highway bridges has been increasing in both volume and magnitude, which even has become one of the main reasons leading to damages and collapse of bridges. Most of the existing regulations for overloading checking are carried out based on various limits of gross vehicle weights and axle loads. However, the results of relevant researches show that weight is only a potential factor but not the dominating factor in threatening the safety of bridges. In this study, the concept of load-effect-based heavy truck is proposed for overloading checking, and then three years of WIM data were collected and used to develop heavy truck models for each truck type, based on the understanding of the characteristics and configurations of heavy trucks as well as the distribution of their main parameters. Furthermore, the typical heavy truck models selected and their possible combinations are applied to a simply supported pre-stressed concrete T-beam bridge model with three loading levels, considering one-lane, two-lane and three-lane loaded respectively, then the induced load effect, deflection and stress are discussed for 20 loading cases. The results show the bending moment caused by heavy trucks moving on multiple lanes is 1.6 times the value of the standard truck model in Chinese specification, and the eccentric loading due to a very heavy vehicle moving on single lane usually lead to more severe effect.

Rollover Prevention and Motion Planning for an Intelligent Heavy Truck

It is very necessary for an intelligent heavy truck to have the ability to prevent rollover independently. However, it was rarely considered in intelligent vehicle motion planning. To improve rollover stability, a motion planning strategy with autonomous anti rollover ability for an intelligent heavy truck is put forward in this paper. Considering the influence of unsprung mass in the front axle and the rear axle and the body roll stiffness on vehicle rollover stability, a rollover dynamics model is built for the intelligent heavy truck. From the model, a novel rollover index is derived to evaluate vehicle rollover risk accurately, and a model predictive control algorithm is applicated to design the motion planning strategy for the intelligent heavy truck, which integrates the vehicle rollover stability, the artificial potential field for the obstacle avoidance, the path tracking and vehicle dynamics constrains. Then, the optimal path is obtained to meet the requirements that the intelligent heavy truck can avoid obstacles and drive stably without rollover. In addition, three typical scenarios are designed to numerically simulate the dynamic performance of the intelligent heavy truck. The results show that the proposed motion planning strategy can avoid collisions and improve vehicle rollover stability effectively even under the worst driving scenarios.

Use of a Hot-Mix Asphalt Plant to Produce a Cold Central Plant Recycled Mix: Production Method and Performance

Cold central plant recycling (CCPR) of asphalt mixtures continues to grow in interest among agencies and asphalt mixture suppliers. However, one implementation challenge has been the need to invest in new equipment to produce the mixture. In 2015, the National Center for Asphalt Technology (NCAT) worked with a local contractor to produce a CCPR mixture through a standard hot-mix asphalt (HMA) plant. The mix was then placed in a test section on the NCAT Pavement Test Track with a highly modified dense graded HMA overlay. The process used to produce the mixture in the HMA plant is outlined along with the performance of the mixture after heavy truck loading in comparison with a control section with a highly modified dense graded hot-mix asphalt in lieu of CCPR. After 17 million equivalent single axle loads the test section containing the CCPR mixture is performing as well as the control section. This shows that CCPR can be successfully produced using an HMA plant, which may encourage mix suppliers and agencies to conduct trial projects with CCPR, implement CCPR into standard practice, and further justify new CCPR equipment investments.

Vibration Analysis of the Drivetrain in Dependence on the Type of Gearbox Suspension Bushing

In the vast majority of technical applications, there is a necessity to transmit the torque from drive to driven machine together with the demand to overcome great distance between given devices. One of the solutions of this problem is the use of a cardan shaft. Operations of connecting shaft and drivetrain are accompanied by oscillations negatively influencing the driver comfort. Main subject of this article is the measurement of vibrations on different parts of a heavy truck and its evaluation by FFT analysis. Measurements are performed with two kinds of suspension bushing which are compared with to each other. Based on the previous measuring, influence of cardan shaft length was also investigated. First of all, dependency on the length of the cardan shaft on deflection angles for V arrangement was evaluated by analytical method. The theoretical introduction is followed by research of eigen frequency depending on the length of the cardan shaft. The results obtained by modal analysis in FEM are verified by experimental modal analysis [1].