The tensile strengths of geomaterials such as rocks, ceramics, concretes, gypsum, and mortars are obtained based on the direct and indirect tensile strength tests. In this research work, the Brazilian tensile strength tests are used to study the effects of length and inclination angle of T-shaped non-persistent joints on the mechanical and tensile behaviors of the geomaterial specimens prepared from concrete. These specimens have a thickness of 40 mm and a diameter of 100 mm, and are prepared in the laboratory. Two T-shaped non-persistent joints are made within each Brazilian disc specimen. The Brazilian disc specimens with T-shaped non-persistent joints are tested experimentally in the laboratory under axial compression. Then these tests are simulated in the two-dimensional particle flow code (PFC2D) considering various notch lengths of 6, 4, 3, 2, and 1 cm. However, different notch inclination angles of 0, 30, 60, 90, 120, and 150 degrees are also considered. In this research work, 12 specimens with different configurations are provided for the experimental tests, and 18 PFC2D models are made for the numerical studies of these tests. The loading rate is 0.016 mm/s. The results obtained from these experiments and their simulated models are compared, and it is concluded that the mechanical behavior and failure process of these geomaterial specimens are mainly governed by the inclination angles and lengths of the T-shape non-persistent joints presented in the samples. The fracture mechanism and failure behavior of the specimens are governed by the discontinuities, and the number of induced cracks when the joint inclination angles and joint lengths are increased.  For larger joints when the inclination angle of the T-shaped non-persistent joint is around 60 degrees, the tensile strength is minimum but as it is closed to 90 degrees, the compressive strengths are maximum. However, an increase in the notch length increase the overall tensile strength of the specimens. The strength of samples decreases by increasing the joint length. The strain at the failure point decreases by increasing the joint length. It is also observed that the strength and failure process of the two sets of specimens and the corresponding numerical simulations are consistence.

The aim of this study was to investigate the withdrawal resistance of T-shaped joints, shear strength and bending moment capacity in the diagonal tensile loading of L-shaped joints made of wooden biscuits.The type of joint members including medium density fiberboard (MDF) and particleboard and the size of biscuits 10 and 20 (one biscuit per joint) were the variables of this study. After constructing the specimens using polyvinyl acetate (PVAc) adhesive, the withdrawal resistance test of T-shaped joints and shear strength and bending moment capacity tests of L-shaped joints were carried out. The results of analysis of variance showed that the effects of independent variables namely, the composite type (Joint members) and the biscuit size on the the withdrawal resistance was significant in the 95% confidence level, also the effects of these independent variables on the shear strength and the bending moment capacity in diagonal tensile loading of the biscuit joints, was significant in the 95% confidence level. According to the results, T-shaped joints made of wood biscuits of MDF members have a higher withdrawal resistance than joints made of particleboard members. the withdrawal resistance of T-shaped joints made of Biscuit size of 20 was higher than that of joints made of Biscuit size of 10.The Shear strength and bending moment capacity in diagonal tensile loading of L-shaped joints made of MDF members were higher than those made of particleboard members. The L-shaped joints made of biscuit size of 20 showed higher shear strength and bending moment capacity in tensile loading, than joints made of biscuit size of 10. generally, the highest amount of tensile and shear strengths and bending moment capacity in tensile loading were observed in the joints made of MDF and biscuit size of 20.

In this paper, the failure pattern of non-persistent joint under U shape cutter was studied by experimental test and numerical simulation. For this purpose, 4 gypsum sample with dimension of 5cm*10cm*10cm containing perpendicular non-persistent joint were prepared.  Samples have 2 vertical non-persistent joint with lengths of 1cm and 2 cm. the angle of small joint related to horizontal axis was 0°, 45°, 90° and 135°. This sample was subjected to U shape cutter loading. Concurrent with experimental test, numerical simulation was performed using Franc2d on the non-persistent joint. Totally 12 numerical model was built that some of them have similar configuration with experimental specimens. The results show that perpendicular non-persistent joint configuration has important effect on the failure pattern.  The compressive strengths have minimum value when small joint angle were 45° and 135°. The comparison between experimental results and numerical output shows that the good accordance was established between experimental tests and numerical simulation.

The aim of this paper is to study the effect of spacing of the joint from ‘u’ shape cutter on the fracture mechanism and to investigate the effect of joint angularity under ‘u’ shape cutter loading on the shear failure mechanism. For this purpose nine sample with dimension of 5 cm *10 cm*10cm consisting non-persistent joints were prepared. The first sets of three specimens have one non-persistent joint with length of 2cm and angularity of 0, 45 and 90. The spacing between joint and top of the sample was 2cm. The second sets of three specimens have one non-persistent joint with length of 2cm and angularity of 0, 45 and 90. The spacing between joint and top of the sample was 4cm. The third sets of three specimens have two non-persistent joint with length of 2cm and angularity of 0, 45 and 90. The spacing between upper joint and top of the sample was 2cm and the spacing between lower joint and upper joint was 2cm. the samples were tested under loading rate of 0.01 mm/s. concurrent with experimental investigation, numerical simulation were performed on the non-persistent joint using FRANC2D. the results shows that the spacing between joint and specimen edge and joint angularity have important effect on the crack growth mechanism. Also, failure mode and failure pattern in experimental test and numerical simulation are similar.

The ecosystem and equilibrium of rivers can be significantly affected by the river bank erosion which can also limit the human access to the rivers. Groyne is an important river restoration structure that prevents bank erosion through deviation of flow from the river banks to the main channel. From the permeability aspect, these structures can be classified into three types of permeable, impermeable, and bandal-like ( hybrid type which includes permeable and impermeable types ). Moreover, these structures can be categorized to straight, T-shaped, and L-shaped configurations. This research aims to investigate the local scour around a new type T-shaped bandal like groyne. The total number of 66 experiments were conducted through a straight flume ( 12 m length, 0.6 m width, and 0.6 m depth ) under non-submerged and clear water conditions. T-shaped bandal like and T-shaped impermeable groyne structures were fabricated in three web to wing length ratios of 0.5, 0.75, and 1. Also, three upstream to downstream wing ratios of 0.5, 1, and 2 and the permeabilities of 33%, 50%, and 60% were selected for the T-shaped banal like structure. The experiments were carried out at the flow discharge of 6 Ls-1, 9Ls-1, 12 Ls-1 and 15 Ls-1 in the presence of the T-shaped impermeable groynes and the T-shaped bandal-like groynes. It was revealed that, increasing the structure permeability resulted in decreasing of the maximum relative scour depth. Under 33%, 50%, and 60% permeabilities of the T-shaped bandal-like groynes, the maximum scour depth was decreased by 63%, 78%, and 83%, respectively compared to the T-shaped impermeable groynes. Moreover, it was observed that the maximum relative scour depth was increased by the average of 46% as for the greater values of structure length. The maximum relative scour depth was also increased for the greater values of flow discharge. It was found that there is no relationship between the maximum scour depth and the ratio of upstream wing length to the downstream wing length of groyne. Based on the results, the permeability and length of the groynes and the flow discharge are among the factors affecting local scouring around T-shaped bandal-like groyne. The significant decrease in the relative scour depth in T-shaped bandal-like groynes compared to T-shaped impermeable groynes indicates that the T-shaped bandal-like groynes have better performance than the impermeable ones in scouring control, structural stability and river bank protection.

The aim of this research was investigating the effect of fiber reinforced polymer (FRP) on the strength of T-shaped wooden joints under tension load. In this regard, T-shaped joints were constructed with beech and poplar species and were reinforced with 1 and 2 layer of carbon and glass fibers reinforced epoxy and vinylester polymers of composite. Joint members were assembled by used of wooden dowels and polyvinyl acetate adhesive and then withdrawal resistance of reinforced joints were studied. Results of variance analysis showed that the independent effect of species of joint members, resin type and number of fiber layers at FRPs was significant at 5% level. Results have indicated that withdrawal resistance of joints constructed with beech species was more than the poplar species. The investigation of the effect of number of layers showed that the withdrawal resistance of the joints reinforced by two layers of carbon and glass fibers was more than one layer. Results of FRPs investigation indicated that use of epoxy matrix in comparison with vinyl ester matrix exhibited better results. In addition, carbon fibers have shown better performance than glass fiber as reinforcing agents. According to the results the best treatment was the joints of beech wood and reinforced by composites with epoxy matrix and reinforced with two layers of carbon fibers.

The rock block volumes are formed due to the intersection of discontinuities in the jointed rock mass. The block dimensions affected by joint spacing, joint orientation, joint sets, are taken to be the most important parameters determining the rock mass behavior, strength parameters, and deformations. In the numerical modeling using distinct element method, the creation of the discontinuities can affect the final results very much. Using 3DEC software, it is possible to create joint sets in four conditions: regular and persistent, regular and non-persistent, non-regular and persistent, irregular and non-persistent. As an important point to consider, the major effect of block dimensions on rock mass behavior, strength parameters and deformation modulus can help to decide which one is most suitable to indicate the real conditions of rock mass. As explained in the previous studies, the use of persistent joints leads to the block dimensions being considered as small ones. In this way, due to the high strength of intact rock compared to the joints, the possibility of instability increases.
Material and In this research, from quantitative point of view, Geological Strength Index (GSI) is calculated, based on block dimensions as an influential parameter, to consider the most appropriate case for creating joints in the numerical method. In this regard, according to valuable studies in Bakhtiari dam structure, the characteristics of discontinuities system and GSI of rock mass are utilized to come up with real conditions. Then, the modeling is done with different conditions of joints, block volume distribution, GSI for each case, and the results are compared with quantitative ones. And then the most suitable case for creation of joints in numerical modeling is suggested by using 3 DEC software, regarding the blocks volumes, type of distribution function, and GSI value. Also, the accuracy of this finding is investigated for other structures, independently of input parameters, by making changes in spacing, and joints persistence as two effective parameters in rock blocks dimensions. Owing to the difficulty in the accurate definition of joints persistence, which is related to dimensions of the location, the numerical models for joint persistence are done in an acceptable level in order to create blocks with high conformity in terms of the dimensions. Then, the comparison is made between block dimensions from perspectives of numerical models and GSI values, to choose the best ones showing high conformity with real conditions.
The comparison of the modeling results using creation of joints in different cases with quantitative results obtained according to geological strength shows that the created block volumes are not properly distributed due to the creation of joints as irregular ones in the two cases of persistent and non-persistent. In this case, the blocks volume changes from a few centimeter to cubic meter, and as the block dimensions increase, the created blocks become bigger. Thus, according to the created blocks volume and the obtained GSI range, the creation of joints is not a suitable method as an irregular one. The creation of regular and persistent joints is not an appropriate method either, as the most created blocks are small, and blocks volume distributions do not comply with quantitative distribution. But with creation of joints as regular and persistent ones, the distribution function of blocks volume in numerical method and quantitative method is log normal. Therefore, according to the created blocks dimensions and GSI range using 3DEC software, the most suitable case is the creation of joints as regular and non-persistent ones.
According to the obtained results in the four cases, when the joints are considered only as regular and non-persistent ones, the blocks volume range is more compatible with real conditions and follows log normal distribution. Thus it can be concluded that the suggested method for creation of joints in the numerical modeling using 3DEC software is more suitable than others considering the rock blocks dimensions and their distributions. This method can be utilized in any structure to accurately define the persistence of joints regarding created blocks dimension.

In nature, rocks contain non persistent joints and in rock slope stability analyses it is assumed that discontinuity is persistent, while stress intensity is centralized attips of non-persistent joints and this stress intensity affects the size and orientation of joint growth in rock and also stability of structures created in it such as rock slope. Fracture mechanics is a science that discusses the probability of joints growth and also fracture propagation path. The development of this science provides the possibility of using actual non persistent joints modeling in rock slope stability as well as controlling mechanical behavior of discontinuities especially in crack tips. By creating rock slopes and changing the matrix of regional stress, intensity of stress occurs in joints tips. If this stress overcomes strength parameters of the joint, it will grow and joint propagation will result. One type of failure that occurs in rocky environments due to crack propagation is toppling whose analysis is one of the most difficult problems in aeromechanics. The aim of this study is to model joint propagation by using the principles of rock fracture mechanics, growth and publication ofnon -persistent and random joints in rock slope with potential of toppling failure. An acceptable numerical method for joint propagation modeling that is boundary element method as displacement discontinuity method (DDM) was selected. As a case study tectonic block IV-2 of Choghart open pit mine was selected and3D geometrical model by random disk method by 3DGMMathematica program was simulated and also 2D cross section was prepared. The amount and direction of joint propagation were calculated by applying boundary conditions, in-situ stresses and stiffness matrix. The mechanical model was created according to geomechanical characteristics reported in stability analysis of this wall. Length of linear elements in joints was considered 3m and propagation step applied was 0.2 over the joint length and the model was run typically in four stages of crack growth. Obtained geometrical model contains early and propagation joints can be used in softwares that geometrical model of joints is essential I analysis but the propagation of joint is not available. So the program code can be used as a complementary method for analysis method as key-groups method and distinct element method (UDEC) to analyze the jointed rock mass

T-shaped joints are one type of beam-column connections in steel structures. Ease of construction, transportation, and installation, as well as suitable ductility, economy, and durability, are the advantages of this type of connection. However, bolting of the T-shaped flange to tubular columns is very challenging due to limited access. In this research, by using through bolts for connecting the T-shaped flanges and the column, the transfer of forces and the rigidity of the panel zone have been provided. This is especially effective in concrete filled tubular (CFT) columns where the passage of concrete through the panel zone is important. On the other hand, the direct transfer of stresses to the column, the stretch of through bolts under cyclic loads, which reduces their performance level, as well as accumulation of bolts, which is caused by large diameter, and four-way connection, especially at a long opening that interferes with the passage of concrete through the panel zone are controversial. Therefore, to provide a suitable solution, in an innovative action, the external diaphragm of the column with through bolts was used simultaneously and the performance of the connection was examined.
In this study, using ABAQUS software, one connection sample with a through bolt and another with an external diaphragm were investigated. The results show that the overall performance of both kinds of connection is quite good.

Structural walls are used extensively in moderate- and high-rise buildings to resist lateral loads induced by earthquakes. The seismic performance of many buildings is, therefore, closely linked to the behavior of the reinforced concrete walls. The analytical models used in this paper are developed to study the push-over response of T-shaped reinforced concrete walls andinvestigate the influence of the flange walls on laterally loaded walls and nonlinear behavior of shear walls, namely strength, ductility and failure mechanisms. A layered nonlinear finite element method is used to study the behavior of T-shaped and rectangular (barbell) shear walls. This paper introduces a computer program to practically study three-dimensional characteristics of reinforced concrete wall response by utilizing layered modeling. The program is first verified bysimulated and reported experimental response of 3-D reinforced concrete shear walls. Subsequently, a study considering eighteen analytical test specimens of T-shaped and barbell shear walls is carried out. Finally, based on analytical results, a new equation for minimum ratio of shear wall area to floor-plan area is proposed.