Annual about 150 thousand tons of old tire is produced in Iran. There is no possibility to dispose of the waste in the environment. Because tire is decomposition with low speed and makes mush pollution in the environment, thus optimal use of these wastes has become a necessary. In this study, tensile, flexural and compressive strength of 28-day and 70-day compressive strength of concrete is studied in the environment of the acid and alkaline. Thus, it is considered the percentage of ash tire by weight relative to the weight of the cement equivalent to 1%, 2%, 3%, and the water – cement ratio equal to 40%, 45% and 50%. Experimental results show that the addition of tire powder, concretes SHOTCRETE improved mechanical properties including compressive strength, tensile strength and bending strength. Also, the mechanical strength of SHOTCRETE containing tire powder is much more than the corresponding conventional SHOTCRETE containing Nano-silica.

As part of the stabilization systems for excavations and slopes, SHOTCRETE today plays an extensive role in civil and mining engineering practices. A great number of efforts have been made during recent years to improve the strength and ductility of SHOTCRETEs. Fiber incorporation can be named as one of these efforts. Based on the type and characteristics of fibers, reinforced SHOTCRETEs display different properties. As a result, advantages and disadvantages of each type of fiber are being studied. This study presents the results obtained from experimental investigations of the influence of waste tire textile fiber addition on strength, ductility, and energy absorption capacity of SHOTCRETEs. After preparing specimens reinforced at fiber contents of 0. 5%, 1%, 1. 5%, and 2%, unconfined compressive strength, Brazilian tensile strength, and three-point bending strength were conducted on all samples. The results show that using the fibers inhibits the brittle behavior of specimens and increases energy absorption capacity. Several advantages of using this fiber can be named such as high entanglement in the matrix, low specific weight of the fibers as compared with mesh and steel fibers, easy pumping, and high durability in damp and acidic environments. Moreover, due to the fact of being waste materials, using these fibers leads to lowering the costs of projects as well as tackling the environmental hazards ensued by burying or burning them.

Extensive damages in a large number of existing buildings under inplane shear has shown the need of structural strengthening techniques for masonry structures. FRP and SHOTCRETE are strengthening techniques which can be used to repair or strengthen masonry structures. Masonry walls strengthened with FRP and SHOTCRETE can greatly increase some behaviour parameters such as strength, energy absorption and stiffness, but the comparison and effect of single-faced FRP and SHOTCRETE layers on shear behavior of masonry walls under lateral loads have not been studied so far. In this research in order to evaluate and validate numerical modelling approaches, two kinds of experimental masonry wall models made by clay bricks and concrete blocks strengthened by FRP and SHOTCRETE were introduced. At the end, modelling and analysis of six walls under lateral loads using the nonlinear analysis of pushover in Abaqus software has been investigated. The results of the analysis show the feasible effect of strengthening unreinforced walls with singlefaced SHOTCRETE and FRP, so that the stiffness and strength of the wall increases significantly due to the addition of SHOTCRETE to one side of the wall. Also, amount of energy absorption increase for FRP is 60-70% and for SHOTCRETEs 70 to 90%. Therefore strengthening by single-faced SHOTCRETE has a more feasible effect.

Summary In this paper, Probability Density Function (PDF) for thickness of the SHOTCRETE cover in tunnel temporary support is investigated. Based on collected data from a recently constructed tunnel in Iran, the proper PDF is suggested. To achieve this, three goodness of fit statistical methods are considered to find the appropriate distribution function. The results show that the Generalized Extreme Value distribution function has the best rank with respect to other distribution functions. Introduction One of the most important issues in the reliability analysis of the structures is proper selection of the distribution function for existing random variables. In tunnels, the problem of temporary supporting system involves many random variables including thickness of the SHOTCRETE. In this research, based on the data obtained from an existing tunnel in Iran, the probability distribution function for the SHOTCRETE thickness is determined by using curve fitting techniques. Methodology and Approaches Different distribution functions have been studied and compared based on three well-known goodness of fit tests, called Chi-Squared, Kolmogorov Smirnov and Anderson Darling. For this purpose, nine points in each section and 43 individual sections are considered in the tunnel route. It is reasonable an individual point in all sections is considered to obtain a distribution function. Also, 15 types of distribution functions are chosen to have an appropriate fit over the data. The EasyFit software is utilized for assessment and finding the appropriate distribution function using the three mentioned goodness of fit tests. Results and Conclusions According to the results, the Generalized Extreme Value Distribution is recommended for PDF of SHOTCRETE thickness in tunnel supporting systems. It is noted that this distribution function has the best rank in all three goodness of fit tests. Although the results are obtained by using data from a specific tunnel project, they can be improved by considering more data from other projects. The distribution function can be used to obtain uncertainties of thickness of SHOTCRETE in reliability analysis of tunnels.

Unreinforced masonry buildings are quite popular in many countries such as Iran, even though they are prone to significant damage against even moderate seismic excitations. In 2003, 26000 people lost their lives and 30000 were injured in southeastern Iran during Bam earthquak. The regional investigations showed an almost total overall collapse of all adobe and masonry buildings. Even to this day, notable number of buildings in Iran is masonry buildings due to low costs, especially in rural areas. Hence, the popularity despite the poor performance has sought researchers to study efficient ways to improve the URM buildings. Generally speaking, masonry buildings are classifed into unreinforced and reinforced,the latter usually beneft from horizontal and vertical steel bars which signifcantly improve strength, ductility and energy dissipation capacity of such walls. Masonry buildings can also be categorized as confned and unconfned. Using horizontal and/or vertical ties usually in the form of lightly reinforced concrete members at the perimeter of walls, their intersection with perpendicular walls and if necessary, around large openings can considerably enhance their ductility and in some cases their strength. Unlike other masonry construction types, the behavior of Confned unreinforced Masonry (referred to CM hereafter) buildings has not yet been fully formulated. This is mainly because of more sophisticated behavioral characteristics of CM walls compared to unconfned Unreinforced Masonry (referred to URM hereafter) buildings. CM is the only masonry system that has been allowed practicing by the Iranian Code of Practice for Seismic Resistant Design of Buildings (Standard 2800) in seismic-prone areas. When it comes to seismic retrofitting of masonry buildings, there are a rather wide variety of available options, e. g. SHOTCRETE, adding steel or FRP sheets on the wall, adding Reinforced Concrete (RC) ties, changing the arrangement and size of the openings, and using Near Surface Mounted (NSM) rods on the walls. Considering the significant number of two-story URM school ‎‎buildings in Iran, there is a need to provide instructions for ‎the ‎type of improvement plan of these buildings. In response ‎to this ‎need, the Organization of Renovation, Development ‎and ‎Equipping of Schools of Iran developed a guideline for ‎the ‎purpose of typifying the improvement plan of these ‎buildings ‎with the SHOTCRETE method in 2021. ‎ In this research, based on the results obtained from five two-‎‎story URM schools, the accuracy of this guideline is ‎evaluated. ‎For this purpose, the investigated buildings in the ‎two cases of ‎flexible roof without ties and rigid roof with ties ‎in ETABS ‎software using shell elements and spectral dynamic ‎analysis ‎method, once based on the requirements of the ‎guideline and ‎once based on the Code 360 was evaluated and ‎retrofitted using ‎SHOTCRETE. ‎ The results of this research show that the guideline ‎in the case ‎‎of flexible roofs leads to ‎minimum vulnerability of the walls of ‎‎the studied buildings. In the case of a rigid roof, the ‎results ‎‎show that according to this guideline, some of improved and ‎‎unimproved walls are ‎vulnerable in both direction,In such a ‎‎way that the ‎average percentage of vulnerable walls in terms ‎of ‎‎relative length for the first floor is 63% in the ‎longitudinal ‎‎direction and 38% in the transverse ‎direction, and for the ‎‎ground floor in the ‎longitudinal direction is 56% and in the ‎‎transverse ‎direction is 17%. ‎

An effective approach for strengthening masonry building is to apply SHOTCRETE  reinforced with mesh on the surface of the wall. It is not possible to assess behaviour of coated walls solely using analytical approaches based on simple equations of theory of elasticity without the use of numerical methods. Unreinforcced masonry wall is modeled in this study using the finite element software "ANSYS" to assess the behavior of walls strengthened with reinforced jacket. The accuracy of the models is ensured by calibrating the model against results from laboratory tests. Then the calibrated model is generalized to model the strengthen wall and finally, the analytical results obtained from masonry walls and strengthen walls and strengthed walls are compared and evaluated.

In many practical measurements, the compressive strength, fc, of standard cubic or cylindrical specimens are considered as actual strength of concrete used in structural elements. However, there are numerous parameters which cause the standard compressive test not to represent actual strength of castled materials, e.g. concrete casting, environment and curing conditions, vibrations and so on. The mentioned difference is, more remarkable in shot Crete which is used in 3D light weight sandwich panels. In this system the thickness of shot Crete wythe is about 50 mm which is minimum based on ACI recommendation for provision of core specimens. The presented work tries to show the estimation of compressive strength of standard cylinder and concrete cores taken from 3D standard elements in 60 specimens and, also, to manipulate experimental relations between these two methods. The current study is concluded with a reduction factor, which shall apply to the standard cylinders strength, fc , as to achieve the actual compressive strength.

Iran is located on Alpine-himalayan earthquake belt. Every few years destructive earthquakes happen in Various region of Iran which causes significant amount of material and human losses. Therefore seismic strengthening of buildings especially historical and old religious building, because of their cultural, historical, heritage and touristic values are of great national importance. The objective of this paper is to study the seismic behavior of a special method of retrofit of Urchin domes. This type of semi-conical masonry dome which are found in southern regions of Iran has not been structurally investigated before. As a model for this study the damaged Urchin dome of Imamzade Jafar shrine in Borujird under 2006 A. D (1385 A. H) Silakhor-Lorestan earthquake was investigated. The strengthening method used is by applying a layer of reinforced concrete (Shot-Crete) to the interior surface of the Urchin dome which was evaluated in this study. After sufficient field studies and measurement, the composite structure of the: Urchin dome, lower double layer spherical dome and the masonry supporting walls and pears were modeled using ABAQUS FEM software. The models were analysed and their frequency and dynamic behavior using time-history analysis (THA) were obtained and compared before and after the application of strengthening Shot-Crete layer. Finally by evaluating the results obtained from these studies, the causes of the failure of the tip of this dome was found to be the excessive acceleration at the tip of the dome and weakness and brittleness of the masonry material due to shearing forces. After strengthening the interior of the dome by a Shot-Crete layer the weakness and vulnerability of the dome under the applied earthquake will be significantly reduced.