Semnan University PressJournal of Rehabilitation in Civil Engineering2345-441511220230501Material Effects on Tangent Modulus of Steel Square Hollow Section117642310.22075/jrce.2018.1741.1152ENSeyed Mohammad RezaMortazaviDepartment of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, IranMiladShakibaDepartment of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, IranBehrouzZaeimdarDepartment
of Civil
Engineering,
Shahid
Rajaee
Teacher
Training
University,
Tehran, IranJournal Article20161115The kind of mild steel, the Bauschinger effect because of strain reversal and strain ageing are indicated to affect significantly the tangent modulus of elasticity. Stub column specimens made from a material that has been pre-stretched in tension have a significantly lower tangent modulus of elasticity than those specimens made from as-received material; the reduction is caused by the Bauschinger effect and a resulting reduction in tangent modulus and yield strength. The reduction happens despite increases in material yield strength due to strain ageing after application of the tensile stretching. This paper has shown great reductions of tangent modulus of elasticity when specimens are made from material pre-stretched in tension compared with as-received specimens. Strain ageing has a great influence in minimizing the tangent modulus of elasticity reductions resulting from prior tensile prestretching. The initial tensile pre-strain of stress-relief-annealed specimens does not affect the tangent modulus of elasticity. No reduction was observed in the tangent modulus of elasticity of specimens prestrained in tension and stress-relief-annealed. The FE analysis according to the ABAQUS code was applied to simulate the stress-strain curves. The numerical and the experimental curves were reasonably similar to each other.https://civiljournal.semnan.ac.ir/article_6423_3f0566d91f89e1e5f529d85efa7884e8.pdfSemnan University PressJournal of Rehabilitation in Civil Engineering2345-441511220230501Control of Road Settlement around Stone-Arch Bridges by Material Modification and Embankment1832665710.22075/jrce.2022.26292.1613ENSajadTavakoliAssistant Professor of Civil Engineering, Ilam Branch, Islamic Azad University, Ilam, IranMohammad HoseinAminfarProfessor of Geotechnical Engineering, Civil Engineering Faculty, University of Tabriz, Tabriz IranSaeedToulabiCivil Engineering Department, Engineering Faculty, University of Ilam, Ilam, IranJournal Article20220212Occurrence of road settlement around bridges is considered as one of the common problems of road operations. In buried bridges, especially in deep valleys, where it is not possible to use soil compaction machinery, significant settlement is observed after road operation. Such settlement mainly reduces the ride quality as well as the safety of the crossing. Based on experience, the deeper the valley and the weaker the soil, the greater the settlement created in these embankments. In this paper, in addition to field assessment of settlement in buried bridges, a suitable method has been presented for embankment around these bridges. In this regard, by finite element method, a sample of bridges buried in deep valleys has been modeled in which the settlement was calculated. The results of the finite element method were compared with the field values of the settlement at one of the studied bridges. The results showed that the settlement was directly related to the width and depth of the valley, the volume of the embankment and the soil type. Also, the results of numerical studies by finite element method showed that the created settlement was strongly affected by the modulus of elasticity of the soil compared to other parameters. If the modulus of elasticity of the materials reduces, the settlement will increase significantly. In this study, a suitable method for embankment around buried bridges in deep valleys has been presented. The results of using this method showed a significant reduction in settlement around buried bridges.https://civiljournal.semnan.ac.ir/article_6657_f5f0d608edd96511ec158d2eff17d46f.pdfSemnan University PressJournal of Rehabilitation in Civil Engineering2345-441511220230501Determining the Dynamic Settlement of the Foundation Adjacent to Slope Using Analytical Method3342665910.22075/jrce.2022.22290.1471ENMohammad JavadShabaniTechnical College of Imam Sadiq, Technical and Vocational University, Babol, IranAliGhanbariDepartment of Civil Engineering, Kharazmi University, Tehran, IranJournal Article20210102Based on field studies, the topographic slope effects worsen the structural damage in an earthquake. It is very vital to determine the amount of foundation settlement adjacent to the slope. In this study, a new analytical model is proposed to determine the amount of vertical settlement of the shallow foundation near the slope. In this analytical model, the inertia force due to the sliding zone mass is considered in the dynamic equilibrium equations. Moreover, it was assumed that stiffness and damping under the foundation linearly increased as the distance from the slope edge increased. In this case, the maximum stiffness and damping at a distance five times as large as the foundation width from the slope edge were considered to be the same as maximum stiffness and damping in the non-slope scenario. The foundation was loaded harmonically by changing the frequency. Comparing the results of this study with the laboratory results leads to this observation that the offered analytical model can well determine the settlement located near the slope. Furthermore, the results showed that the settlement of the foundation near the slope edge was twice as large as the settlement in the absence of a slope. Also, the settlement of the foundation became equal to that of the non-slope foundation at a distance of 4 times as large as the foundation width from the slope edge. Furthermore, with increasing slope angle and declining the foundation distance from the slope edge, due to vertical harmonic load, the foundation settlement amount increases.https://civiljournal.semnan.ac.ir/article_6659_fae52e0c80d421365e9f3ee77753f146.pdfSemnan University PressJournal of Rehabilitation in Civil Engineering2345-441511220230501A Modeling Strategy for Predicting the Response of Steel Plate-Concrete Composite Walls4363666010.22075/jrce.2022.26725.1632ENMohammad SadeghBarkhordariPhD, Department of Civil & Environmental Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, IranJournal Article20220330Shear walls are among lateral load resisting systems which are used to provide adequate stiffness, strength, and nonlinear deformation capacity to withstand strong ground motion. Usually at the base of the wall, these structures tolerate inelastic deformations subjected to strong ground motions. Researchers have offered composite walls to solve these problems. Steel plate-concrete composite (SCC) walls have been regarded as an alternative to reinforced concrete walls in terms of seismic performance and constructability. In this study, a new semi-macro modified fixed strut angle finite element model is proposed to predict the nonlinear response of SCC walls using OpenSees. A new modified fixed strut angle model and a quadrilateral flat shell element are adapted to the analysis of SCC shear walls. The numerical model is validated using the results of a set of experimental data reported in the literature. Comprehensive comparisons between analytical-model-predictions and experimental data suggest that the numerical model can accurately simulate the steel plate-concrete composite wall responses.https://civiljournal.semnan.ac.ir/article_6660_34b46af2f4a03b79621082f37ae38bdf.pdfSemnan University PressJournal of Rehabilitation in Civil Engineering2345-441511220230501Macro Modeling of Column Removal in RC Frames with Consideration of Importance Factor and Infill Walls6493670910.22075/jrce.2022.24267.1539ENSeyed AliHassanzadehTeacher at Building Cluster, Ministry of Education, Lorestan, IranHamid RezaAshrafiAssistant Professor, Department of Civil Engineering, Razi University, Kermanshah, IranMehdiKomasiAssociate Professor, Department of Civil Engineering, Ayatollah Ozma Borujerdi University, Borujerd, IranJournal Article20210820In this study, the effect of importance factor (IF) on RC frames with and without infill walls, in both with and without opening conditions, is evaluated against progressive collapse. For this purpose, RC building with the intermediate moment frame system for three levels of importance factor that these levels are intermediate, high, and very high IF is designed. OpenSees program is utilized for modeling RC frames. For this aim, the accuracy of modeling of column removal and infill walls are compared with experimental researches. In the present study, nonlinear dynamic analysis (NDA) and push-down analysis (PDA) were used for evaluating RC frames against progressive collapse in each column removal scenario. Analysis results showed that the effect of the importance factors in NDA and PDA are reduced to less than 24% and 13% when the infill walls are modeled in the frames. In the frame without infill walls, the influence of the importance factor is increased up to 36.1%. Also, in this study, it was found that the role of importance factors depends on the place of the removed column, which the effect of middle column removal is relatively twice than the corner column removal due to more redundancy. Other results about infill walls effects and opening in infill walls are presented in the paper. Finally, a proposed approach for column removal in NDA via OpenSees program is introduced, and its high accuracy is shown. This developed algorithm can remove any element of structure in different time intervals.https://civiljournal.semnan.ac.ir/article_6709_b55a012be2f1cdf85b83a0fccdf94bb2.pdfSemnan University PressJournal of Rehabilitation in Civil Engineering2345-441511220230501Numerical Analysis of J-Hook Connectors’ Effect on the Performance of Steel-Concrete Composite Shear Walls94112693110.22075/jrce.2022.23015.1494ENSeyed MohammadFarnamAssistant Professor, Department of Civil and Architect Engineering, Faculty of Engineering, Raja University, Qazvin, IranMohsenKhorshidiMaster of Civil-Structural Engineering, Daneshestan Institute of Higher Education, Saveh, IranJournal Article20210330The use of shear walls is one of the diverse approaches to deal with lateral forces, and composite shear walls are among the different types of these walls. Composite walls consist of two steel sheets and a concrete core between them joined by shear connectors. In this system, the concrete cover can also participate in the load-bearing of the section. Shear connectors are used for bonding concrete to the steel sheet in the wall. Due to the necessity of creating a composite functionality, these connectors play an important role in the behavior of the system. Moreover, the effect of J-hook connectors on steel-concrete composite shear walls is investigated. For this aim, an experimental model is simulated and validated in the ABAQUS software. After verifying the accuracy of the model, a parametric analysis is defined and further studies are performed by using a nonlinear in-crescent static method (pushover method). The results of this study show that the J-Hook connector positively affects increasing load capacity and reducing the out-of-plane displacement of the composite shear wall. Additionally, the number and location of the connectors have a great impact on the both load and buckling capacity of the steel plate. Above all, adding concrete to the steel shear wall which consists of two steel sheets, not only rise the wall's bearing capacity by 14 percent, but improve the performance of the interaction between materials by about 17%.https://civiljournal.semnan.ac.ir/article_6931_a08de725f5567fe99932a52fcff4d00d.pdfSemnan University PressJournal of Rehabilitation in Civil Engineering2345-441511220230501Bond Strength of Fiber-Reinforced Mortar and Concrete Interface under Pre-Stress113130694910.22075/jrce.2022.25326.1572ENAliSaberi VarzanehPhD in Structural Engineering, Department of Civil Engineering, Engineering Faculty, Imam Khomeini International University, Qazvin, IranMahmoudNaderiProfessor, Department of Civil Engineering, Engineering Faculty, Imam Khomeini International University, Qazvin, IranJournal Article20211122Shrinkage and improper compaction of the repair layer are among the main reasons for the adhesion drop. Shrinkage results in cracking and improper compaction causes fine pores in the interface. Due to the fact that shrinkage and non-compacting are the main reasons for reducing strength and adhesion, therefore, in this paper, research has been done in this regard. The present study aimed to investigate the effect of polypropylene fibers on the shrinkage of mortars and bond of mortar/concrete interface. Moreover, the impact of diverse pre-stresses on the adhesion between mortar and concrete was evaluated by imposing pre-stresses on fiber-reinforced mortars. Adhesion was assessed by the “twist-off” and “pull-off” tests. Furthermore, the effect of fibers and pre-stress on the adhesion examined using SEM images and X-ray diffraction. It is necessary to assess the compressive strength of concrete and mortar in the field. Therefore, the aforementioned semi-destructive methods were employed to investigate the in-situ compressive strength of mortars at different ages. For this purpose, the correlation coefficient between the in-situ and laboratory methods was defined and the scaling curves were plotted to convert the in-situ test results into compressive strengths of the mortars. The obtained findings indicated the positive effect of pre-stress on adhesion. In addition to their mechanical effect, the indirect effect of fibers on the chemical properties of the mortars reduces shrinkage and augments adhesion. Moreover, given the great relationship among the conclusion of “pull-off” and “twist-off” methods, the cost-efficient and available twist-off apparatus can be used for adhesion measurement instead of the costly and import pull-off apparatus. Adding 0.3% of polypropylene fibers to the mortars enhanced the bond strength by 76.8% and 41.7%, respectively and reduced the shrinkage of the mortars by 11%. An initial stress of 0.5 kg/cm<sup>2</sup> increased the shear and tensile bond strength at the age of 90 days by 12.8% and 13.3%, respectively.https://civiljournal.semnan.ac.ir/article_6949_c0a14c63812773bca6d70c883db5fd23.pdfSemnan University PressJournal of Rehabilitation in Civil Engineering2345-441511220230501Characteristics of Recycled Concrete Aggregate and its Implementation for Pavement Base Applications: A Review131152668210.22075/jrce.2022.23836.1523ENShravan KumarGanguResearch Scholar, Department of Civil Engineering, Transportation Division, National Institute of Technology, Warangal-506004, IndiaShankarSabavathAssistant Professor, Department of Civil Engineering, Transportation Division, National Institute of Technology, Warangal-506004, IndiaJournal Article20210630Significant amounts of Natural Aggregate (NA) materials are being used to meet the requirements of pavement structure. Simultaneously, enormous amounts of demolition waste, such as demolished concrete and reclaimed pavement materials, are dumped into landfills along roadsides, creating pressure on the environment. Therefore, the recycling of demolished materials and their utilization for pavement construction would result in conservation of natural aggregates, this would alleviate the problems related to geo-environment and bring several benefits for the environment and ensure sustainability. Several studies have been carried out to describe the mechanical properties of recycled concrete aggregate (RCA) with and without stabilization. A thorough understanding of performance-related engineering properties of unbound RCA and stabilized RCA is essential for mechanistic-empirical pavement design. This paper reviewed the mechanical properties such as compaction, California bearing ratio, resilient modulus, and permanent deformation in the case of unbound RCA, and unconfined compressive strength, flexural strength, and stiffness for stabilized RCA from accessible works of literature on the application of RCA for pavement base. The findings from the literature indicated that RCA is source-dependent, moisture sensitive, and subjected to particle breakdown under wheel load that results in reduced shear strength. Further, if RCA is treated with mechanical stabilization by geosynthetics, the interface shear strength properties improve, and permanent deformation is reduced. Chemically stabilized RCA is a promising technique as its strength and durability complied with stabilized NA. Therefore, this review will be helpful for pavement engineering practitioners to explore RCA use in pavement base or subbase layers.https://civiljournal.semnan.ac.ir/article_6682_07afc66bf4a224506b83a19be2f3ece2.pdfSemnan University PressJournal of Rehabilitation in Civil Engineering2345-441511220230501Seismic Improvement and Rehabilitation of Steel Concentric Braced Frames: A Framework-Based Review153177665810.22075/jrce.2022.26179.1611ENAtefehSoleymaniPh.D. Candidate of Structural Engineering, Department of Civil Engineering, Shahid Bahonar University of Kerman, Kerman, IranHamedSaffariProfessor, Department of Civil Engineering, Shahid Bahonar University of Kerman, Kerman, IranJournal Article20220205The ability of structures to withstand seismic loads is the most important feature of earthquake engineering. Because of their high stiffness and lateral strength, concentrically braced frames (CBF) are one of the most prevalent resisting methods in engineering structures. Under moderate seismic events, CBFs have limited lateral displacement capability, resulting in structural damage and substantial post-earthquake expenses. However, when these constructions are exposed to moderate to severe seismic events, their compression members start to buckle. Buckling these compression members in CBF also reduces ductility and causes hysteresis curve deterioration. As a result, they become brittle and have a limited capacity to dissipate seismic energy. On the other hand, conventional CBF constructions exposed to seismic hazards may display an unacceptable soft-story mechanism, in which drift and damage are localized in a single-story, while all the other stories are comparatively unscathed. Several research works have improved CBF seismic behavior, and different strategies have resulted in seismic improvement. This paper presented an overview of seismic improvement modifications of CBF, which have been studied in the literature. A review of current studies to better understand and analyze CBF behavior is presented.https://civiljournal.semnan.ac.ir/article_6658_2f97e4a4e54e04c583968494474367dd.pdf