JOURNAL OF NEW APPROACHES IN CIVIL ENGINEERING
Year:2020 | Volume:4 | Issue:3|Papers Count:5

Nowadays, using FRP materials as reinforcing rebars in concrete structures, bridge decks and roads is common to prevent rusting of steel rebars. The purpose of this study was to strengthen the flexural strength of the concrete beams with FRP rebars and also to improve the weak beams that were reinforced with these rebars and reinforced by attaching the CFRP Laminates in the lower part of the beam along its length. For this purpose, two main parameters of ductility and flexural strength of sections reinforced with FRP rebars, designed in 12 models and subjected to nonlinear static analysis (pushover) in ABAQUS software and then the GFRP sample is also subjected to cyclic loading. The results show that to reinforce the beams if these rebars are used in the absence of steel bars, it is better to use the AFRP rebar because it provides flexural strength of beam sections about 8 to 18% more than the sections reinforced with CFRP and GFRP rebars and if the ductility is considered, It is advisable to use GFRP rebar which has about 7-15% more ductility than AFRP and CFRP sections, and if the weak section is strengthened with CFRP Laminates under cyclic loading, the flexural capacity can be more than 2. 28 times to the nonlinear static analysis (pushover).

The distance between two buildings in urban areas is called expansion joint. The lack of this distance or lack of proper noticing about this distance makes the clash of two buildings when a terrible earthquake happens. In such cases, using viscous dampers are effective. Two 8-4floor frames with normal concrete moment system were chosen. The left-hand structure is usually modeled with two insets and the right – hand structure is modeled with 3, 4, 5 insets. Models were designed with existing regulations. Once, all models are modeled with expansion joint and next time with viscose dampers in the middle of expansion joint. Then non-linear dynamic analysis with seven accelerometers is achieved on all structures and acquired results from this analysis were compared with each other. Finally, it was cleared that the existing of dampers caused the reduction of answers like movement and drift of floors.

Landslides are one of the most common natural phenomena that cause subsidence as well as deformation and displacement. Due to this point, the importance of detecting displacement in sensitive areas such as the dam and the surrounding area increases. Radar interferometry is currently one of the best techniques for assessing ground deformation. But this method alone is not suitable for structures that have horizontal deformation and displacement. In this study, in order to increase the accuracy and efficiency in detecting unstable points, we have used a combination of radar images and GPS satellite observations on the Givi Dam area in the period 2017 to 2019. Using Small Baseline Subset (SBAS) analyses, point stability analysis by Iterative Weighted Similarity Transformation (IWST) method and classical adjustment method were found to be two excellent methods for detecting displaced points and validating the results. So that both methods identified the same points on the dam and the points outside the dam. Among these points in the area around dam GR4 has the highest displacement of 5. 57 mm and in the direction of the satellite line of view obtained from radar interference-1. 61 mm per year and point P9 on the dam has the highest displacement of 9. 06 mm and in line with the line of sight of the satellite obtained from radar interferometry is 1. 96 mm per year. Also, as the distance between GPS stations and pixel points decreases, accuracy increases dramatically.

Today, the used method by most researchers to design new structures and retrofitting the existing structures is to reduce the movements and forces resulting from the earthquake in the structure. Accordingly, control of the structural behavior through the application of controlling forces on the structure by means of appropriate tools and separating the structure from the ground motion has been formed. The passive energy dissipation devices are grouped by seismic protection, which are quickly categorized into two groups of dependent velocity and non-dependent velocity devices. In structural control systems, damping has a crucial role in controlling seismic responses. On the other hand, nonlinear behavior of structures and the amount of hysteresis energy that is known as the structural hysteresis damping has a very important effect on the amount of structural damage and controls the collapse prevention state of the structure. By varying the damping values of the structure, the nonlinear behavior of the resistant elements of structure changes and the amount of hysteresis energy is affected. In this study, to investigate this topic, the structures with a number of different stories have been modelled in SeismoStruct software and dampers have been applied to the structure. By observing the results, the damping causes decreasing the seismic response of the structures, but the relationship between the increasing the damping and lowering the responses is not linear. But in general, the amount of damping value reduces displacement, drift, and base shear and increasing the performance level of the structures. The highest internal force reduction for the damping ratio 10, 20 and 30% has been 35, 39 and 43%, respectively. Also, the maximum reduction of the base shear for the damping ratio 10, 20 and 30 is 55, 59 and 64%, respectively.

According to the statistical data of the Iranian Seismological Center in the first three months of 1398, a total of around 2880 earthquakes were recorded and determined in Iran and borderline regions. The largest earthquakes with the Richter magnitude scales of 4-5. 1 occurred in Kermanshah province, Iran, and its suburbs. In addition, a severe earthquake occurs in Iran every 7 years on average which leads to dramatically high financial loss and casualties. According to earthquake induced losses and damages, the building industry has intended to lighten and provide industrial construction of structures to facilitate better support against seismic forces. In this respect, light-weight steel structures have been applied by engineers as one of the excellent industrialization and lightening approaches. This modern building system has greatly welcomed in developed countries and has used as an alternative to traditional systems. This system can be employed for rebuilding in earthquake-stricken areas and construction in prone-to earthquake regions. This study was conducted aiming at reviewing features of light-weight steel structure to be used in prone-to-earthquake and earthquake-stricken areas.