The determination of tunnel support, required for tunnel stability and safety, is an important debate in tunnel engineering field. Q-system classification is a technique used to determine the support system of a tunnel in rock. The problem is that all required parameters of support system are not accessible. On the other hand, such accesses are very costly and time consuming. Therefore, it is impossible to determine the Q-value in all cases. This paper identifies the most influential parameters of Q-system using SPSS program. Then, it adopts multi-variable regression (MVR) and genetic algorithm (GA) methods to propose a relation for predicting the Q-value using three influential parameters. To this end, 140 experimental data are used. To assess the obtained models, 34 new experimental data, which are not in the primary dataset, are used. The innovation of this paper is that instead of six parameters, the Q-value is determined using three parameters with the highest impact on it instead of six parameters. In this study, the MVR model, with RMSE=2.68 and correlation coefficient=0.81 for train data and RMSE=2.55 and correlation coefficient=0.80 for test data, showed better performance than GA model, with RMSE=2.90 and correlation coefficient=0.82 for train data and RMSE=2.61 and correlation coefficient=0.84 for test data.

In this paper, the artificial intelligence is employed to design a Fault-Tolerant Controller (FTC) for structural vibrations. The FTC is designed to reduce the probability of damage considering sensor fault. For this purpose, Neural Networks (NNs) are used as fault detection and accommodation and fuzzy logic is used as a controller. This control strategy requires two groups of neural networks. The first group of neural networks finds the faulty sensor by estimating the structural responses and comparing them with the responses obtained from the sensors. The second group has the task of estimating the response of the faulty sensor using data obtained from healthy sensors. To evaluate this method, the time history analysis of a 3-story benchmark building equipped with accelerometers and active actuators has been used. This evaluation is based on determining the probability of structural damage and the generation of fragility curves under forty ground motions. To develop fragility curves, the criteria specified in the FIMA 356 (IO, LS and CP) for the moment frame based on the inter-story drift are used. This study show that in the absence of the neural networks, sensor fault reduces the performance of the fuzzy controller and it is even possible to increase the structural responses compared to the structure without the controller. In addition, results demonstrate that the proposed control strategy can rectify the deterioration of sensor faults and decrease the probability of failure.

The long-term effects of scour have been identified as one of the primary reasons for bridge failure. To evaluate the performance of the bridges against scour, it is essential to assess the conditions of the bridge foundation including the depth of the piles. Sonic Echo (SE) has been a favorable nondestructive method to evaluate the condition of unknown bridge foundations in the recent decades. Previous studies have shown that the results obtained from SE tests can be affected by a variety of factors such as the pile-to-soil stiffness ratio, length-to-diameter ratio of the pile, presence of defects and anomalies near the pile head, striking method, and hammer type. Although previous studies have discussed such affecting factors, there is a lack of comprehensive investigation regarding the effect of striking method and hammer tip type specific to wood piles supporting bridge decks. In the current study, the effect of striking method and hammer type on the success of SE tests conducted on wood piles has been scrutinized by investigating various options of striking methods and hammer tip types. After comparing different options, superior ones were identified and recommendations for better conducting the SE tests on unknown wood bridge foundations were presented. Numerical simulations were also performed to support some of the conclusions.

The production of ordinary Portland cement (OPC) as the most expensive constituent of concrete is associated with destructive environmental effects and significant energy consumption. Thus, the use of supplementary cementitious materials such as Natural or synthetic pozzolans is a fundamental solution that affects the kinetics of hydration of cementitious materials. In this article, to evaluate the effect of ball clay in the presence or absence of silica fume on the performance of cementitious materials, compressive strength and ultrasonic tests were performed at replacement weight percentages of 0, 10 and 20% for ball clay and 0 and 7% for silica fume. Also, thermodynamic modeling during hydration was carried out based on the Gibbs free energy minimization. The results showed that mere presence of ball clay does not have a positive effect, but it can improve the structure and strength of cement in the presence of silica fume, since it resulted in complete consumption of portlandite and consequently increasing C-S-H gel. In addition to examine the type and volume of phases formed during hydration, the optimum substitution of ball clay and silica fume was studied. Accordingly, the best overall performance of ball clay was observed in the 10% substitution in the presence of 7% silica fume.

Building industry as one of the greatest industries in Iran comprises a significant share of waste generation in the country. Since a large quantity of the generated construction waste is buried due to the lack of a recycling protocol, it leads to an undesired waste of resources and causes severe environmental issues. This paper provides a study on the problem of material loss/construction waste in the Iranian Building Industry regarding the impact of relevant shortcomings in the stages of design, construction and supervision as the main phases of construction process. This paper includes the case studies from Isfahan, Mazandaran, Qazvin and Zanjan provinces, with a focus on the most important elements underlying construction waste generation. It also presents the experts points of view on prefab and conventional construction methods considering construction waste generation through a questionnaire-based survey. In general, the results show that Iranian project managers, engineers, contractors and workers believe that from 40 to 100 percent of construction wastes can be reduced via application of prefab construction methods. The results indicate that prefabrication can be considered as a solution to waste reduction in the Iranian Building Industry, whereas there is a dominant conventional method application in the industry.

This paper evaluates the effect of slot existence with limited length between flanges and web junction of I-shaped beams at the region of moment connections on vertical force and shear stress distribution in beam flanges and web at connection section in comparison with classical theory of stress distribution. The main purpose of this research is to evaluate the efficiency of the slot in connections such as slotted web beam to column connection in modern age. The issue of the slot has many benefits but very little studies have been done on it. Accordingly, one hundred and twenty models with two moment connections under the concentrated static load in mid span have been made for doing parametric study in ANSYS Workbench finite element software. The linear static analysis was done on all constructed models. Variable parameters in these models for parametric study include slot length between flange and web junction in connection region (from 0 to 190 mm), beam length, beam section height and Poisson’s ratio of beam material. In all models the amount of shear stress in section height over the section vertical axis in connection region and also the devoted contribution from force which goes to flanges and web under the concentrated load on mid span have been calculated. Performed studies have shown that vertical shear stress distribution in beam to column connection section with moment connection differs a lot from what is stated in mechanics of materials equations. Practically the available equations in regulations which state that web receives the entire vertical shear and ignore the contribution of flanges are not reliable. In addition, studies have shown that the slot existence in junction of web and flanges in connection section with limited length can has great effect on the quality of vertical shear stress distribution over the section of connection and also the slot existence has great effect on the reduction of shear stress in flanges and increase in shear stress in web according to classical theory. As a total result, nowadays slotted web beam to column connection can be used as a fantastic and simple idea to improve modern connections behavior.

In the recent years, non-connected piled raft foundation has been considered as an economical and practical deep foundation in the situation that high shear and concentrated loads may occur at the connection of the raft and pile head. This paper was presented an experimental study of a square foundation on the effects of parameters such as S/D, L/D and etc. in two cases of connected or non-connected piled raft system under the eccentrically loaded raft. The results was showed that square raft in the case of S/D = 3 and L/D = 8, the bearing capacity of the non-connected piles is more than that of the connected piles. The results of the experiments was showed pile length is more effective than the pile spacing in connected pile raft system. However by decreasing pile spacing, bearing capacity is increased in non-connected pile raft and pile spacing is more effective than the pile spacing in non-connected pile raft system. Comparison of bearing capacity and settlement indicated in the non-connected piled raft system, the longer piles not only has not much effect in increasing bearing capacity significantly, but also has lower effect on the reduction of the settlement. Also in non-connected piled raft system by increasing the pile spacing reduced BPI (bearing pile index) wile in connected piled raft system increased.

The elements of the concrete structure are most frequently affected by cracking. Crack detection is essential to ensure safety and performance during its service life. Cracks do not have a regular shape, in order to achieve the exact dimensions of the crack; the general mathematical formulae are by no means applicable. The authors have proposed a new method which aims to measure the crack dimensions of the concrete by utilizing digital image processing technique. A new algorithm has been defined in MATLAB. The acquired data has been analyzed to obtain the most precise results. Here both the length and width of the crack are obtained from image processing by removing background noise for the accuracy of measurement. A semi-automatic methodology is adapted to measure the crack length and crack width. The applicability of the program is verified with the past literature works.

Stiffness matrix of the four-node quadrilateral plane stress element is decomposed into normal and shear components. A computer program is developed to obtain the straining modes using adequate and reduced integration. Then a solution for the problem of mixing straining modes is found. Accuracy of the computer program is validated by a closed-form stiffness matrix, derived for the plane rectangular as well as square element. It is shown that method of integration has no effect on the straining modes, but it influences the eigenvalues of the bending modes. This effect is intensified by increasing the element aspect ratio, confirming the occurrence of shear locking.

Various materials have been utilized for ground improvement techniques based on geoenvironmental compatibility. The application of lime mortar in soil has been catching the attention of researchers and engineers. However, there is a lack of research on the variation of moisture content in soil affecting the mechanical behavior of lime mortar. In this study, large-scale laboratory tests were conducted on approximately thirty specimens to evaluate the size effect on stiffness and load bearing capacity of compacted lime mortar (CLM) columns and clayey soil under different saturation conditions. In addition, approximately forty small-scale laboratory tests were carried out on dry clay, dry CLM column and lime mortar specimens to evaluate the unconfined compressive strength (UCS). According to results, UCS of CLM column under small-scale condition was higher than that of the large-scale. Moreover, high moisture content had a significant influence on the stiffness of improved ground and the bearing capacity of CLM columns. Finally, validation of results indicated that numerical model predictions are in agreement with experimental results.