Journal of Rehabilitation in Civil Engineering
Volume:11 Issue: 3, Summer 2023

Today, with the expansion of transportation, several road construction projects have been implemented in several parts of the world. The aim of this study is to stabilize and test sand using cement and drainage wastewater from the ceramic industry. Use of drained wastewater is to reduce the environmental pollution caused by drainage wastewater and reduced consumption of natural resources. In the first stage, the potential of off-site production by the factories and the advantages of using it were investigated. The optimal mixing plan was then obtained by performing a UCS test on samples that were made with different amounts of cement and wastewater. Other specifications of the desired mixture were: single gravity resistance, elasticity modulus, UCS, loss of resistance in saturation and microscopic structure of the particles. In the final stage, the efficiency of the mixture was studied using numerical modeling by finite element method. According to the results obtained from the experiments, it was found that adding 7.5% cement and 12.5% of dried wastewater, the UCS of sand increase from 0.005 MPa to 0.3 MPa and the sand elasticity modulus increase from MPa 5 to 65MPa. The specimen resistance did not increase significantly since the tenth day, and its saturation caused the resistance of the specimens to be reduced by 50%. The results of EDX and XRF tests revealed that the desired water included heavy metals. in addition use of wastewater reducing the consumption of natural resources, reduces the entry of heavy metals into the environment and urban environments. The level of surface treatment was obtained using sand-shaped modeling; which was considered as a substrate stabilizing element, and other pavement layers. The sum of the summands obtained from the modeling with the maximum allowed values was compared which provided satisfactory results. Finally, the processed sand could be used by deep mixing method to stabilize the subgrade of roads.

Masonry infill walls are commonly used as partitions and exterior walls in many countries. Generally, the masonry wall is executed without any gap from the frame, which leads to the interaction between the structural frame and the infill wall. Interaction between the structural frame and the masonry infill wall can damage the frame and the infill wall. Therefore, it is necessary to find a solution to improve the performance of masonry infill walls in the structural frame. Isolation of the masonry infill wall from the surrounding frame by polymeric material is the idea of this paper to decrease the damage to the structure and masonry infill. In this essay, Finite element models of steel infill frame and isolated infill frame subjected to In-Plane cyclic loading are developed in ABAQUS. For this purpose, three one-bay, one-story masonry-infilled steel frames with different frame ratios of height to the length (H/B) isolated by different polymeric materials with various thicknesses were investigated. Isolation of masonry infill can reduce the base reaction about 25%. In the Isolated Infill wall, the drift’s amount increases about two times compared with the unseparated infill wall. Therefore, it damages the masonry infills up to moderate drifts, while full interaction is still in place drifts are large. Also, infill walls isolated by a softer polymer, have better performance. In brief, isolation of infill wall using polymeric materials improves the behavior of the infill and frame.

Recent years have seen a significant increase in structural engineers' interest in the assessment of reliability and structural safety. The Reliability-Based Design Optimization (RBDO) method has been utilized to create the most efficient and safe design of structures. Although there have been several theoretical advances in reliability analysis, computational barriers still occur in realistic problems. The purpose of this paper is to provide a process for the optimization of dome truss structures based on reliability. For this purpose, a flowchart including the process of Deterministic Design Optimization (DDO) and RBDO was presented. An evaluation of the reliability of the structure is made by using random variables to represent uncertain parameters. Throughout this study, random variables such as the module of elasticity, material density, and the cross-sectional area of the elements are considered. The deterministic constraints for DDO are the vertical displacement of free nodes and the demand-capacity ratio of all members. Also, reliability index 3 is set as the minimum target reliability index. Meta-heuristic algorithms can be used to achieve optimal design and appropriate safety since mathematical calculations are time-consuming. As part of this study, the Enhanced Vibration Particle System (EVPS) and Vibration Particle System (VPS) have been applied to DDO (incorporating reliability assessment) and RBDO of three dome trusses. The results were obtained using the processes of RBDO and DDO without any deviation in the acceptable space. The solution of RBDO will increase the weight and safety of structures.

Using bolt shear connectors in Steel-Concrete-Steel (SCS) slabs is very important due to producing a complete steel plates connection and adjusting the sandwich thickness desirably. Therefore, in the present research, a numerical study is conducted on the flexural behavior of SCS sandwich slabs with stud-bolt shear connectors under the effect of the quasi-static concentrated load. For this purpose, first, the experimental specimens extracted from the previously published study were numerically modeled and quasi-statically analyzed using explicit dynamic analysis. Then based on the tests, the models were validated. Subsequently, the effect of the parameters, including the thickness of steel plates, stud-bolts diameter, the concrete core thickness, center-to-center distance of stud-bolt connectors, and the concrete core strength was evaluated based on the numerical models on the failure modes and the force-displacement curve. Finally, using the experimental setup and gene expression programming (GEP) algorithm, several numerical models were planned to predict the maximum strength of the slabs and a simple relation was proposed. The maximum strength resulting from the proposed relation and numerical models had an acceptable agreement with an error of 11% based on mean absolute percentage error (MAPE).

Corrosion is one of the most important and common factors in the destruction of structures. Among all kinds of structures, corrosion of submerged structures is of great importance and prevalence due to the impossibility of direct visibility, high reconstruction cost and special environmental conditions. The work done in the field of corrosion of these structures has mainly dealt with modeling the problem in the form of mathematical formulation or using soft computing methods. The work that has established the connection between these two methods has not been done, to the best of our knowledge. This article aims to develop a model in order to estimate the chloride diffusion coefficient in rebar corrosion in submerged concrete structures. Present study seeks to address the estimation of chloride diffusion coefficient, which is one of the determinant factors in computing the corrosion time/rate of rebar’s. In this article, using the Monte Carlo sampling method and the formulas available for chloride diffusion coefficient, we produced 2000 artificial data samples. A variety of methods such as support vector machines (e.g., linear, quadratic, cubic, Gaussian), K-nearest neighbors (fine, medium, coarse KNN), and two methods of ensemble learning (bagged tree, subspace discriminant) are applied to predict the chloride diffusion coefficient. The results indicated that the quadratic support vector method (with 93.5% accuracy) is the best technique in estimating the chloride diffusion coefficient. Best KNN model (medium KNN) and best ensemble method (bagged tree) have accuracy of 59.9% and 81.3%, resp.

In the recent development of synthetic and natural fiber in the industry of cement materials, polypropylene fiber become cheap and globally available. Due to its high mixability with soil and high tensile strength, it has been used for strengthening the soil. In the current investigation, cyclic triaxial experiments were performed to examine the dynamic response of fiber reinforcement in a poorly graded sand subjected to cyclic loading. Fiber reinforced sand (FR) mixtures are prepared by short polypropylene fiber of 6 mm length with different percentages of fibers (0.25%, 0.5%, and 1.0%) and compared with unreinforced sand (UR) All the samples were tested at confining pressure of 50 kPa. All samples were tested at three different axial strains 0.075%, 0.5%, and 1.125%, respectively under no drainage condition. Maximum shear modulus is found at 18.16 MPa for sand with 0.5% fiber and the damping ratio found decreased with increasing fiber content and reduced to 15% for sand with 1.0% fiber content. Also, the effect of shear strain and repetitive loading cycle on damping and shear modulus behavior is presented in this study.

One of the most widely used and applicable solutions for limiting the damages of earthquakes to steel structures is using Metallic Yielding Dampers as a type of passive devices to dissipate the received energy. Maintaining a proper balance in the design of these devices is a delicate matter as each of the different types have advantages and disadvantages. In this research, different types of metallic dampers are compared using finite element simulation which is performed by means of ABAQUS package. Modeling process is described and verified by comparing the results to a previously published experimental paper on the subject. For assuring more accuracy a mesh convergence analysis is performed to determine the suitable mesh size. Afterwards, cyclic and pushover analysis are performed on each damper and results are presented and discussed. Effective stiffness and damping of each damper, both general and average, is extracted using proper equations and finite element results. Finally, for deeper understanding of dampers behavior, internal forces of the dampers are derived and compared. It was shown that design equations are fairly accurate. As the height of the dampers increases, their effective stiffness and damping reduces and the dampers behavior leans towards flexural behavior. Based on cyclic and pushover analysis, Steel Plate Dampers (SPD) have the highest stiffness and energy dissipation. Also, SPD and Double Pipe Dampers (DPD) are the most suitable to reach a demanded stiffness, damping and have the most stable performance. At the end of the paper, a list of conclusions is presented.

Evaluating the efficacy of Nano CaCO3 particles on amelioration of fatigue and rutting behavior of asphalt binder is the principal aim of this article. To this end, asphalt binder specimens are fabricated by incorporating various amounts of Nano CaCO3 (0.3%, 0.6%, 0.9%, and 1.2%) with asphalt binder 60-70. Fatigue and rutting performance of the asphalt binder specimens are examined by implementing linear amplitude sweep and multiple stress creep recovery experiments. Results indicated that incorporating Nano CaCO3 with the asphalt binder specimens enhanced their resistance to rutting. Asphalt binder samples containing Nano CaCO3 showed higher potential for compensating the induced strains than unmodified samples. Also, by adding Nano CaCO3, the asphalt binder specimens showed improved fatigue behavior. Asphalt binder samples modified with Nano CaCO3 exhibited better behavior when subjected to cyclic loads than unmodified ones. Also in all cases, the asphalt binder specimens containing 0.9% Nano CaCO3 demonstrated the best performance.

The process in which response of soil influences the motion of foundation and vice-versa, is known as Soil-Foundation Interaction (SFI). This paper deals with the different types of soil-foundation interaction models useful for structural as well as geotechnical engineers and researchers for safe and economical raft design. The study offers a gist of all the models in literature and their applications. Several approaches for analysis which include analytical methods and numerical methods have been described here. Analytical models based on Winklerian and Continuum approach have been discussed. Moreover, modified forms of such approaches have also been discussed. In general, all the models make use of a parameter known as Modulus of Subgrade Reaction to model soil interaction. This parameter can be calculated either through experiments or empirical formulas. Different numerical methods have also been presented along with a few literatures. Further, some of the studies on raft foundation are also included.