فصلنامه رویکردهای نوین در مهندسی عمران
سال چهارم شماره 1 (بهار 1399)

The elastic behavior analysis of post-buckling of the frames is complex. When a frame is exerted force over critical load, it begins large deformations. In this case, the theory of small deformations is not valid for the structure, and it must be used the theory of large deformations. Post-buckling analysis of the elastic structures always requires solving method with a set of nonlinear differential equations based on equilibrium equations. In designing the members under the axial force or the axial force and the bending moment in the structure, in addition to the yielding criterion, the buckling criterion is important too. However, if the length of the member is too much or the member is slender, before yielding, buckling occurs in the member, which requires the member to be checked for possible buckling. In this research, the post-buckling behavior of the lateral unbraced frame is analyzed with the help of Elastica theory. For this purpose, the first step is to analyses a cantilever column by the Maclaurin Series method. By examining the results of the post-buckling behavior of this column with the previous research, the verification of this method has been evaluated. In the following, due to the verification of the method, the large deformations and post-buckling behavior L-shaped frame are investigated. To analyses the frame, it is necessary to solve a nonlinear equation system. The Maclaurin Series method has been used to obtain nonlinear equations. With the help of the equations, the frame deformations diagrams have been plotted. Mathematica software is used to draw charts and solve nonlinear equations. In the following, with the modelling of the frame in Finite Element ABAQUS software, the comparison of the accuracy of the software results with this analysis has been checked and the convergence of the responses has been examined.

Given that in refineries typically account for about third of the total investment cost of building sedimentary ponds, increasing the efficiency of these ponds, in addition to increasing the useful life of other parts of the treatment plant, is very important economically and the environmently. The main purpose of this study is to study 16 models of urban sewage sedimentary basins and to evaluate their efficiency with the help of data analysis. Matlab software was used in this evaluation, and in the end, the average efficiency of the two methods, CCR and BCC, was calculated to have a general result. The first place went to model number two and the last place went to model number nine. Comparisons between performance ratios have been used to compare results. The correlation coefficient between CCR and BCC results is 0.754.

Accurate river discharge estimation is one of the most important pillars in the management of surface water resources, especially for appropriate measures in flood situations, droughts, and drinking, agricultural and industrial applications. In this research, to estimate the discharge of the Zarrineh River, daily data and data of the Zarrineh River with a statistical period of 10 years at the site of the Sari Station of Qomish were used using the NeuroSolutions software. In this research, 60% of the data for training, 20% of data for validation and 20% for the rest were also used for testing. Various networks have been compared with multi-layered perceptron neural network (MLP), general predictor and radial base function. And the results indicate that the Multilevel Perceptron Neural Model (MLP) with the lowest mean square error was the best neural model. In this study, several networks with different transmission functions (TanhAxon, SigmoidAxon, LinearTanhAxon, and LinearSigmoidAxon) were compared. And the results indicate that the LinearTanhAxon transmission function with the lowest mean square error was the best transfer function. Also, networks with one and two hidden layers were compared and the results showed that the network with a hidden layer was better than the hidden two-layer network.

Due to the importance of concrete structures in today's life and the use of concrete at different levels, the repair of damaged parts of concrete surfaces, especially in the cracks section is very important. In repairing cracks, the cause of the crack must first be determined. If the crack is caused by structural factors such as subsidence, shear force, frame displacement, etc., the reasons must first be investigated and then repaired. Cracks caused by it, but if the cracks are caused by non-structural and surface factors, it is easier to fix the defects. In repairing deep cracks, it is necessary to inject appropriate restorative materials into the cracks, which requires effort and It has high accuracy. Crack repair includes steps such as cleaning the inside of the crack from debris, installing special hose heads to inject restorative materials, creating a cover layer for deep cracks, injecting restorative materials with pressure and sometimes with the help of a device, removing the cover layer and removing headgear and Finally, the final leveling of the repaired surfaces is smooth and uniform. Restorative materials can include a variety of epoxy materials, concrete adhesives, cement mortar, grout, etc.

The use of a variety of bridge improvement and reinforcement methods has made significant progress in recent decades. Before strengthening, a study of the bridge should be done on how and in what way the useful life of the bridge can be extended. In this study, the seismic behavior of reinforced reinforced concrete columns was evaluated and compared with the distance of metal jacket and concrete jacket with dimensions of 3.5 x 3.5 m with reinforcement network. Models for estimating its seismic parameters were analyzed non-linearly geometric and materials. Use of concrete jacket box with dimensions of 3.5 x 3.5, increase energy absorption, final strength and ductility by 38, 14, 13 percent. Therefore, it can be concluded that by using a concrete jacket, the amount of items mentioned in the concrete column system can be increased.