Effect of aging on the physical-mechanical characteristics of an asphalt mixture with rubber

This paper evaluated the physical-mechanical characteristics of two asphalt mixtures. One mix with conventional asphalt and the other with asphalt modified with recycled rubber grain. For this purpose, the asphalt mix designs were made by means of the Marshall methodology. Subsequently, asphalt mixtures were manufactured to analyze the action of monotonic loads (indirect tensile strength) and dynamic loads (resilient modulus). Previously, each type of asphalt mix was subjected to short- and long-term aging conditions, following Aastho guidelines. It is concluded that the incorporation of recycled rubber grain makes the changes in mechanical properties with aging not very noticeable in relation to mixtures without this material.

Experimental study of fixed-ended RC deep beams under cyclic and monotonic loading

Reinforced Concrete (RC) deep beams are commonly used in structural design to transfer vertical loads when there is a vertical discontinuity in the load path. Much experimental research has been conducted on simply supported deep beams, yet only a few research is carried out using monotonic loads. In this paper, an experimental investigation is conducted to study fixed-ended reinforced concrete deep beams under cyclic and monotonic loads. Five specimens were experimentally tested. The specimens have similar geometry but different reinforcement details. Four specimens were tested under cyclic load and one specimen under monotonic load for observing the deflection of the mid-span where the load is applied, crack patterns, failure modes, and shear strengths. The results show that the web reinforcements are more effective than longitude bars in fixed-ended RC deep beams to increase their shear capacity.

Experimental Studies of an Asymmetric Multi-Bolted Connection under Monotonic Loads

This article describes the experimental studies of a preloaded asymmetric multi-bolted connection in the exploitation state. The construction of two stands were introduced: for bolt calibration and for evaluating the bolt forces in a multi-bolted connection. The bolts were tightened in a specific optimal sequence, in three passes, monitoring the force values in the bolts using a calibrated strain gauge measuring system. The studies were conducted for the selected multi-bolted connection on an Instron 8850 testing machine. The measurement data were saved in MATLAB R2018b Simulink. The measurement results were analysed statistically and are presented via charts showing the distributions of the normalised values of the bolt forces as a function of the linearly increasing and decreasing exploitation loads. We show that the forces in individual bolts, after unloading the multi-bolted connection, change in relation to the initial values of their preload.

Flexural capacity of RC beams strengthened with near-surface mounted steel bars

An experimental study carried out to observe the flexural capacity of reinforced concrete beams strengthened with Near Surface Mounted (NSM) steel bars is presented. The test was carried out on nine concrete beams. All tested beams were subjected to two-point monotonic loads. The ratio of longitudinal reinforcement (1%, 1.4%, and 2.4%) and NSM bars (1D16 and 2D16) were used as test variables. It was found from the test result that NSM steel bars significantly increase the flexural capacity of reinforced concrete beams. However, the strengthened beams failed in brittle mode, as indicated by a sudden drop of beams capacity. An analytical study was also conducted to obtain the flexural response of the specimens through all ranges of elastic and post-peak load. The prediction of the flexural capacity of the beams compares well with the test result.

Numerical analysis of the behavior of light concrete panels with variations of thickness and door opening position in resisting static monotonic loads

This study covered numerical analysis models of lightweight concrete panels with a variety of thicknesses and door opening positions. The objective of this study was to determine the influence of the dimension of lightweight concrete nonstructural panels with door openings in resisting static lateral loads. The lightweight concrete became generally used since its’ effectiveness in reducing gravity loads. Therefore, the lateral deformation of buildings due to the earthquake became smaller. However, the behavior of the lightweight concrete panels as non-structural elements still needed to be explored, especially under influence of structural elements when an earthquake occurred. There were three variations of the door opening positions on the panels. The varied thicknesses were 40 mm, 50 mm, and 60 mm with and without the addition of wire mesh reinforcement. The panels were subjected to increased static monotonic loads until the panels were collapsed. The analysis results were the relation curves of loads and deformations, and the shapes of deformation that occurred on each model. The analysis results of each panel showed different behaviors and values. In general, the variation of thickness resulted in the conclusion that the thickest panels were able to resist higher loads. The use of wire mesh affected significantly panel behavior. The panels with wire mesh became more rigid so that the resisted loads were higher, but the deformation became smaller, and vice versa while the panel without a wire mesh resisted lower loads but the deformation became larger.

Experimental and Numerical Study of Mechanical Behavior of Welded Steel Plate Joints

This paper describes a study of welded steel plate joints using experimental and numerical methods. The objectives of this study are to observe the mechanical behavior of welded plate joints under monotonic and cyclic loads, identify their damage degradation processes, and provide useful test data for future damage analysis of beam-column connections in steel frame structures. Six specimens were designed, of which three were tested under monotonic loads, and the other three were tested under cyclic loads. The test setup consisted of three plates arranged in a cruciform and connected by two groove welds. The monotonic and cyclic loads were applied to the free end of the two outstanding plates, inducing a pulling force on the welded joint. Because the only element studied in the present work is the weld, the sizes of the three plates were kept constant. The responses of these welded plate joints are discussed in terms of their experimentally and numerically obtained mechanical parameters, hysteretic behavior, strain variations, stiffness degradation, damage process, and failure modes. The results show that the energy damage model outperforms the displacement damage model in terms of indicating the degree of damage. Furthermore, if designed according to code, all these welded plate joints perform satisfactorily.

Performance of high-strength concrete one-way slabs with embedded BFRP bar reinforcement

In this paper, a theoretical study has been concluded using ANSYS-15 software to investigate the performance of reinforced concrete one-way slabs with embedded basalt fibre reinforced polymer (BFRP) bars under monotonic loads. Six slabs have been considered, two were simply supported, and four were continuous each with two-span. Several parameters have been studied, such as continuity condition, reinforcement ratio, the position of the reinforcement and the effect of replacement basalt bars by steel bars. It is found that the finite element analysis (FEA) agree with experimental results in a range of 1% - 9% in deflection compared with the maximum difference of ACI440 committee of 49%. For simply supported slabs, it is found that increasing the reinforcement from 0.2% to 0.5% resulted in increased capacity by 86%. For continuous slabs, it is observed that increasing the reinforcement for top and bottom from 0.2% to 0.5% resulted in increased capacity by 60% while the maximum deflection is reduced by 56%. Moreover, it is found that with an efficient distribution of bars a slab with a reinforcement ratio of 0.7%, the load capacity is improved by 12.5% and a reduction in maximum deflection 46%. Furthermore, it is found that for simply supported slabs, it is better to use higher ratios of BFRP reinforcement,0.5% instead of 0.2% due to a good improvement in capacity. Regarding dissipation in energy, it is found that the difference in predicting toughness by FEA by ANSYS was 1% - 15% for simply supported slabs while for continuous slabs the dissipation in energy was in the range of 20% - 50% compared with experimental results.