Evaluating the impact of excavator bucket capacity on the output of a haul truck in different variants of their positioning

When studying the influence of excavator bucket capacity on haul truck loading time, it is necessary to assess the technical and economic performance of the complex. If the cost of the machine shift of the complex will not cover the increase in productivity, then it is inexpedient to use this complex. This issue requires further, more detailed study and performance of detailed technical and economic analysis. Also, it is necessary to consider classical recommendations about ratio of excavator bucket capacity and haul truck body. It should be noted that at present, there is a significant divergence in the size range of excavators: powerful, with a large capacity bucket, rope shovels are used for mining the coalless zone; small maneuverable hydraulic shovels – for mining the coal-bearing zone. In this paper, we will try to combine the first and the second: consider hydraulic excavators with maximum bucket capacity, which is reasonable to use when mining overburden. In addition, a detailed study of the options of mutual arrangement of excavator and haul truck has not been performed until recently, this work is intended to fill this gap.

Probability-Based Static Truck Loading Model for Rural Bridges in Saskatchewan

A study was conducted to establish a new truck load model intended for the evaluation and design of bridges with simple spans of 20m or less located on rural roads in Saskatchewan. Monte Carlo simulation was used to generate truck data sets based on site-specific traffic conditions determined from a traffic count program conducted between 2008 and 2012 across all 296 rural municipalities, and data collected from six weigh-in-motion stations in the province from January to December 2013. All axle weights and spacings were modelled as probabilistic parameters. The critical truck configuration featured a truck tractor with a steering axle and tandem axle group, and a truck trailer with a tridem axle group. Truck models with a common axle configuration but varying weights were developed for various reference periods that reliably reproduced extreme nominal load effects over those periods. The use of other data sets may lead to different results.

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.

Research on innovative reinforcement of prestressed T-beam bridge

PurposeIn order to understand the status of the bridge reinforcement process, the construction process monitoring of the reinforced bridge is carried out. The T-beam bridge was tested using the truck loading test. The displacements and concrete strains of the bridge at mid-span were measured during the test.Design/methodology/approachThis paper describes an innovative technique, external prestressing, used to strengthen a 36-year-old prestressed T-beam bridge. This paper introduces the construction process of the prestressed reinforcement method, and makes a theoretical analysis of the reinforced bridge through the establishment of the reinforcement model.FindingsThis study showed that the structural capacity and performance of the bridge were enhanced with externally prestressed steel strand strengthening.Originality/valueThe innovative reinforcement method of prestressed T-shaped bridge is put forward, which has guiding significance for similar bridge reinforcement and maintenance.

Development Of A Quick Design Method For Composite Concrete Slab-Over Steel I-Girder Bridges For Project Bidding

In bridge analysis, designers calculate maximum bending moment, MT, and shear force, VT, of a bridge girder under truck loading, then use available truck fraction, FT to generate the longitudinal live load effects. This Thesis presents structural analysis of different girder configurations subjected to CL-W truck loading. Girder geometries include single-, two-, three- and four-span girders. The maximum shear, deflection and moments were plotted and then used to develop equations to represent their values. Furthermore, a software was developed to perform composite steel I-girder design. The software optimizes the I-girder size based on CHBDC design procedure. Using the developed software, a parametric study was conducted to determine the required composite moment of inertia, moment of inertia of the bare steel section and steel web area to satisfy all design requirements. Empirical equations for these three properties were developed to assist bridge designers in estimating steel I-section sizes for contract bidding.

Curved Concrete Slab-On-Steel I-Girder Bridges

A parametric study was conducted, using the finite-element method, to study the load distribution characteristics of curved composite I-girder bridges under truck loading. The influence of several geometric parameters on the moment, and deflection distribution factors, as well as warping stresses in straight and curved composite I-girder bridges was examined. For straight bridges, the moment distribution factors were correlated with those specified in the Canadian Highway Bridge Design Code of 2000, CHBDC. Also the magnitudes of warping stresses in the steel bottom flanges were correlated with the specified limits in bridge codes. The results showed that the CHBDC moment distribution factors significantly overestimate the structural response of straight bridges considered in this study. It was also observed that the curvature limitation specified in the CHBDC to treat a curved bridge of low curvature as a straight one underestimate the structural response.