Abstract: Assessment of the behavior of damaged structures as well as determination of the locations and the depths of cracks in multiple cracked structures are very important and attractive for many researchers. This article presents some results on the determination of the vibration shape function of a multiple cracked elastic beam element, which is modeled as an assembly of intact sub-segments connected by massless rotational springs. Algorithms and computer programs to analyse changes of natural mode shapes of multiple cracked beams have been determined. Numerical analysis of natural mode shapes of cracked simple support beams using the obtained expression shows a good agreement in comparison with the well-known analytical methods. The methodology approach and results presented in this article are new and the basis for building an efficient method to identify cracks in frame structures using wavelet analysis of mode shapes.

Abstract: One of the most important problems that the river engineers have long been faced with lateral intake from rivers is sedimentation in intakes. Formation of the saddle point nearby the intake entrance is one of the main reasons for entry of the sediments into the intake channel. Using the structures in the rivers causes change of the flow pattern and consequently changing of the formation location of the saddle point. The submerged vanes are one of the structures that are installed with different dimensions and configuration in front of the intake channel to control the sediment issues,. In this study the impact of the submerged vanes dimensions and configuration on the formation location of saddle point has been investigated. The FLUENT mathematical model has been used for the simulation. Various range of the parameters has been considered for them based on the recommended range, and the simulations have been performed in three intake ratios of 0.11, 0.16 and 0.21. The results showed that increasing the vanes height has a positive effect on intake conditions, and results in formation of the saddle point in a distance farther from the intake entrance and omission of the return flows. Utilization of submerged vanes with larger transverse distance is better for intake from rivers as no flow from downstream side of the intake channel returns to it. As the intake ratio increases the saddle point forms at a distance closer to the intake entrance, and the return flows are entered into the intake from the downstream corner of the intake entrance. Formation location of the saddle point is independent from other parameters.

Abstract: It is understandable that recycled materials and clean energy technologies have a lot to do with green sustainable architecture. Therefore, it may be expected that nowadays, contemporary architects emphasize on the use of recycled materials, smart grids and clean energy technologies more than ever. Suggesting a guideline for the optimum usage of recycled materials, considering the required materials in construction industry is the purpose of this research. Therefore, the most crucial questions of this research are: 1- What are the most important energy saving criteria regarding to environmental sustainability in future sustecture? 2- How reuses of recycled materials affect environmental aspects? The method in this research is a combination of quantitative and qualitative methods in which the approach is to solve the problem and answer the questions of construction industry and especially saving clean energy technology. The results of the paper show that usage of recycled materials is not competitive in market-price although it is so fruitful for achieving goals and objectives of green architecture. The results indicate that future sustecture is in need of reuse of recycled materials especially in contemporary architecture of developing countries.

Abstract: Once the behaviour of reinforced concrete moment resisting frame structures is investigated, it is concluded that the performance of beam column connections is not satisfactory. In order to understand the complex mechanisms and satisfactory behaviour of beam column connections, lots of investigations have been done. The most critical zone in reinforced concrete moment resisting frames would be the beam column connection. The behaviour of beam column connection once it is subjected to large forces during earthquakes has a great impact on the response of the structure. The shear failure has a brittle nature which is not a desirable structural performance during earthquakes. Two new types of shear reinforcements design are introduced in this study for the purpose of reaching a higher performance and material capacity for the connection and hence, the structure. These two shear reinforcement designs working simultaneously with other reinforcement systems and concrete have a better performance compared to that of conventional methods. The first specimen is made according to conventional method of design as control specimens in conformance with Euro code EC2 & EC8. The second specimen introduces a continued shear resistance system against discontinued conventional shear resistance system (stirrups) which is called “Single Square Spring Shear Resistance System” (SSSSRS). The third specimen possesses two continued square spring systems twisting together and making a parallel system called “Double Square Spring Shear Resistance System” (DSSSRS). A comparison was made between the performances of the improved shear reinforcement systems of beam-column connections against the control specimens. It was concluded that a lower deflection along with higher energy absorption was achieved for “Single Square Spring Shear Resistance System” (SSSSRS) and “Double Square Spring Shear Resistance System” (DSSSRS) compared to control specimens.

Abstract: The most commonly accepted method in evaluation of the mechanical properties of metals would be the tension test. Its main objective would be to determine the properties relevant to the elastic design of machines and structures. Investigation of the engineering and true Stress-strain relationships of three specimens in conformance with ASTM E 8 – 04 is the aim of this paper. For the purpose of achieving this aim, evaluation of values such as ultimate tensile strength, yield strength, percentage of elongation and area reduction, fracture strain and Young's Modulus was done once the specimens were subjected to uniaxial tensile loading. The results indicate that the properties of steel materials are independent from their thickness and they generally yield and fail at the same stress and strain values. Also, it is concluded that the maximum true stress values are almost 15% higher than that of the maximum engineering stress values while the maximum true strain failure values are 1.5% smaller than the maximum engineering strain failure values.