Not surprisingly, Garbage is an integral part of human life; subsequently its collection and burial are the major environmental problems. In this research, materials obtained from the wet waste of Tehran city have been used as a basic supplement material in the stabilization plan including: the soil (85-100%), lime (0.5-1.5%), Portland cement (0.25-0.75%), and this green material (2-15%) (85 samples in total) with the approach of optimizing the materials through the compressive test, Atterberg limits, the wet or dry granulation, a new proposed dissolution test, moisture sensitivity and density based on both the most economical method and environmental conditions. The best mix design was, therefore, opted to combine 5% of the green stabilizing materials incorporating optimized cement and lime because of the A4 classification, changing to a convenient grain size, compressive strength increases, modification on Atterberg limits, and the remarkable performance in terms of the durability test results. 

This research uses a nonlinear finite element analysis to evaluate and validate two experimental specimens. The Hognestad stress-strain model is used to express the uniaxial compressive behavior of concrete to define three-dimensional concrete in the ABAQUS software, and the linear model is utilized to introduce its tensile behavior. Furthermore, a bilinear model with kinematic hardening is used to simulate the behavior of the steel. Both corner and knee joints, including transverse beams and slabs, are investigated using experimental results from different aspects, including force-displacement hysteresis diagram, the effect of stiffness deterioration, fractural mode, energy absorption rate, and the contour of fracture, and von Mises stress. This study examines two different models which present the predictive modeling, so it is shown that the current model has remarkable power and high reliability by taking into account some important effective parameters in the modeling, such as vulnerable regions, design codes defects, the impact of concrete confinement in large plastic strains, and local buckling. To sum up, this research not only provides a reliable model with the lowest inaccuracy in the study of concrete corner beam-column under seismic load but also presents a simplification in the modeling process that highly reduces analysis time. 

Mode I crack propagation in prestressed concrete sleepers B70 is simulated by a fracture mechanics approach. The plastic damage model, which takes the non-linear behavior of concrete into account, is utilized to calculate crack length and crack mouth opening displacement (CMOD). Numerical data from prestressed concrete sleepers B70 under three-point bending load are compared with those of the proposed fracture mechanics model. In this study, fracture mechanics parameters of prestressed concrete sleepers are investigated. Sleepers with the length of initiation crack of 5 to 45 mm (with 10 mm steps) and the width of initiation crack of 2 to 8 mm (with 2 mm steps) are analyzed. Sleeper cracks are created in the notch and both of its sides. These analyses confirm that the structural behavior of prestressed concrete sleepers can be predicted by a simple fracture mechanics model provided that the related material properties like KIC, crack length and CMOD, are known.

B70 mono-block pre-stressed concrete sleepers are one of the most common sleepers in Iran's railways industry. They have been used in many of the country's railway transition lines. The B70 types of sleepers are classified as pre-stressed concrete beams; therefore the value of pre-stressing force is one of the most important parameters in the field of sleepers' structural designing. Selecting high pre-stressing force due to the fact that it increases the steel bars strength, could increase the possibility of longitudinal cracks formation before service loading, especially if the tensile strength is low. Therefore, pre-stressing force and tensile strength are two important factors for investigating the sensitivity of longitudinal crack formation and propagation in sleepers. Sensitivity analysis has been conducted for tensile strength of concrete and the pre-stressing force in the steel bars, by using finite element method. It could be clearly seen in the results that increasing the tensile strength of concrete, increases the cross section capacity. This increase in the capacity does not have a direct relationship with the increase of the tensile strength. Also the numerical model indicates a linear behavior between different pre-stressing forces and maximum tensile stress around the dowels. Applying higher pre-stressing force values can increase the possibility of longitudinal cracks prior to service loading of the sleepers and also long-term sleepers' service life.

This paper presents an investigation on pre-stressed concrete sleepers based on the principles of fracture mechanics in concrete material. To evaluate fracture mechanics parameters pre-stressed concrete sleepers with different initiation crack length varying between 0mm and 45mm increasing by 5mm steps are used. A three-point bending loading condition is considered. Finite element software is employed to model the sleepers and to calculate the parameters of fracture mechanics such as KIc and crack growth. Finally, in this study for validation, load-displacement diagram of 5 experimental samples is compared with numerical model of finite elements for validation of model. The paper shows that an expansion in crack instability follows from increasing crack-to-depth ratio, initial toughness, the crack stability and crack unstable toughness, the crack instability expansion begins. The paper also shows a good agreement between the numerical and experimental results via comparing the results of the 5 samples with the numerical model.

In the network of Iranian railways, pre-stressed concrete sleepers are more popular than the other types due to their high performance. One of the defects observed in these sleepers is longitudinal cracks caused by irregular and excessive pressure before and during the track operation. These cracks usually initiate from the rawlplug locations and propagate to the middle or even to the whole lengths of the sleeper. This excessive and additional pressure in rawlplug positions are due to the water freezing, existence of rock fines or fine aggregates in the fastening holes, deformation of the rawlplug or a combination this effects. This paper presents a test methodology named as Katrak test to exhibit failure planes in non-strengthened and strengthened (transversely reinforced) sleepers. In this study, the effects of the extra pressure in rawlplug positions are simulated by applying cylindrical pressure inside the rawlplug holes using a physical and numerical (FEM) models. The results show that the Katrak test and simulation performed could be an appropriate method for studying sleeper behaviour and formation of longitudinal cracks under excessive pressure.