Shear friction capacity of self-consolidating concrete

An experimental research was developed to evaluate shear transfer in self-consolidating. Three concrete mixes were prepared, one conventional and two self-consolidating, differing on the proportion of the coarse and fine aggregate used. Nine push-off specimens, containing steel reinforcement passing through the shear plane, were tested, to evaluate the ultimate shear stress and shear plane displacements. Shear strength of self-consolidating concrete specimens were higher than conventionally vibrated concrete. The experimental results were compared to the shear strength estimated by literature and code based equations, yielding conservative results of these equations for both types of concrete, especially the models that disregard the compressive strength of concretes.

Estimation of friction capacity of driven piles in clay using artificial Neural Network

The load capacity of driven piles is a crucial mechanical property, and correctly determine the corresponding value is important in geotechnical engineering. Concerning piles driven in clay, the load capacity is mainly associated with the side resistance of the pile. The soil load capacity of conventional piles is determined by different methods and then reassessed by the static load test. Nonetheless, this method is time-consuming and costly. Therefore, the development of an alternative approach using machine learning techniques to solve this problem has been investigated recently. In this work, the backpropagation network model (ANN) with a 4-layer structure [4-8-6-1] was introduced to predict the frictional resistance of pile driven in clay. The dataset for the development of the ANN model consisted of 65 instances, extracted from the available literature. The performance of the proposed ANN algorithm was assessed by two statistical measurements, such as the Pearson correlation coefficient (denoted as R), and Root Mean Square Error (RMSE). In addition to the original contribution, the present work conducted a step further toward a better knowledge of the role of inputs used in the prediction phase. Using partial independence plots (PDP), the results of this study showed that the effective vertical stress and the undrained shear strength were the prediction variables that had a significant influence on the friction capacity of driven piles.

Effect of edge distance on shear friction capacity of steel plates anchored with reinforcing bars in comparison with headed bolts

The shear friction capacity calculated using clauses 11.6.4 to 11.6.10 in ACI 318-14 or clauses 11.5.1 to 11.5.6 in CSA-A23.3-14 do not take into consideration the effect of edge distance on the shear friction capacity. The main objectives of this research are to study the effect of edge distance on the shear friction capacity by means of a specifically designed experimental program, to determine the minimum edge distance to develop the shear friction capacity, and to derive an expression for reduction of shear friction capacity for edge distances less than the minimum edge distance. The study involved testing eight specimens. In four specimens, a steel plate was anchored using welded reinforcing steel bars, and in the other four specimens the steel plate was anchored using headed concrete anchors (bolts) (HCA). The steel plates were tested under shear load at edge distances of 75, 150, 225, and 300 mm (3.0, 6.0, 9.0, and 12.0 in), for the two types of anchorage. The results were compared to design values according to ACI 318-14 and CAN/CSA-A23.3-14 standards. An equation is derived to compute the minimum edge distance after which the full shear friction capacity is developed. Another equation is derived to compute the proposed shear capacity for reinforcing bar anchors for edge distances less than the minimum edge distance.

An Evaluation of Relationship with Polished Stone Value and Skid Resistance Value Based on a Laboratory Investigation

Aggregates which are the main component of asphalt concrete play a major role in loading transfer and skid resistant performance of asphalt concrete. Therefore, reduction in friction resistance of aggregate would lead to a decrease in overall skid resistance of asphalt concrete which is a commonly used road pavement surface material. This research aims to evaluate relationship of aggregate friction capacity through the polished stone value and asphalt concrete skid resistance. In this study, a series of polished stone value tests on the study aggregate of limestone and sandy mudstone and British pendulum tests for skid resistance value of polished hot mix asphalt (HMA) slab. An accelerated polishing machine was used to create reduction of skid resistance of HMA slabs. Test results showed that reduction of polished stone value (PSV) of limestone 47.6% leads to a decrease of skid resistance value (SRV) approximately 43.8% of HMA slabs. Furthermore, 14.5% reduction of PSV of sandy mudstone causes a decrease of 20.3% SRV of HMA slabs. Finally, a relationship linear regression between PSV of aggregates and SRV of HMA slab was established.

Analysis of Side Friction on Urban Arterials

The influence of the side friction activities on the speed has been analyzed in the present study by conducting series of traffic field surveys. Pedestrian movements, parked vehicles and entry-exit of vehicles from surroundings, and wrong way movements are observed from videos and analyzed to estimate weighing factors. To examine the combined effects of all the activities the weighing factors are used to determine total value of side friction on the road. The study suggests model to estimate average speed of vehicular stream with the effect of side friction and volume on the roads section. It was found that the vehicular speed decreases as side friction increases at all the levels of traffic volume. However, no change in the speed was observed at lower level side friction. Capacity value obtained for combined data based on Greenshield’s theory that showed 9% reduction in the value considering with and without side friction.