AMIRKABIR JOURNAL OF CIVIL ENGINEERING (AMIRKABIR)
Year:2017 | Volume:48 | Issue:4|Papers Count:13

Groynes are one of the most prominent structures that used in shore protection to control the littoral sediment transportation. This structure can be used submerged and provide the necessary beach protection without negative aesthetic impact. Although, submerged structures adopt for beach protection, the shoreline response to these structures is not well understood at present. The objective of this study is to predict sediment transport in the vicinity of submerged groyne and comparison with non-submerged groyne with focus on a part of the coast at Dahane SAR Sefidrood, Guilan Province, Iran where serious coast erosion has occurred. The simulations were obtained using a one-line model, in this paper, a linear model is presented to estimate, shoreline deformation in the presence of these structures. The result of the present study show that using submerged groyne can have a good efficiency to control the sediment and beach erosion without causing severe environmental impact to the coast. The important outcome from this study may be employed in optimum design of groyne systems in marine projects. Comparison of the predicted results with those obtained through field measurements shows the efficiency of the proposed model.

Reinforced masonry buildings are technically and economically suitable options for earthquake-prone countries. Inadequate connections between the components of these structures cause damage and destruction in an earthquake. Percentage and connection type between wall and concrete slab are the most effective parameters on safety of these buildings. In this article a model for the seismic behavior of reinforced masonry (RM) building subjected to push-over analysis has been presented. The modeling of the RM structure with concrete slabs has done in ABAQUS, using explicit finite element model. The proposed finite element model has been verified by comparison with experimental data available in the literature and then five models including one, two and four story buildings in different situations have been modeled. Bending length, distance and diameter of joint bars between the walls and concrete slab have been investigated and some recommendations in this field have been presented.

The advantages of buckling restrained braces (BRB) attract the researches and engineers attension to use this bracing system. High ductility, high-energy dissipation capacity and symmetric hystresis behavior are the main advantages of this system that is the most effective system to resist the earthquake induced lateral forces. Disadvantages of conventional bracing system such as low ductility, low energy dissipating capacity and local as well as global buckling with unsymmetrical hysteresis performance in tension and compression are the main reason to rehabiliate and or replace this system with the new generation of braces. Buckling restrained brace (BRB) is an energy-dissipating member that inhances the structural stiffness, energy dissipation and ductility. There are few worldwide code of practices provide some recommendations about the bukling-restrained bracedframes where as most of them do not deal with such system. This paper illustrates the good performance of buckling restrained braces used for RC frames. This article determines the behavior factor for RC frames braced with buckling restrained braces. For this puepose RC frames with four, eight, twelve and sixteen stories (each having three and five bays) were considered in this study. All frames designed in accordance with Iranian Standard 2800 and P9-INBC for concrete structures. Analyses for all structural models were carriedout utilizing nonlinear static pushover method. The results indicate that the average value of behavior factor for all models corresponding to the ultimate limit state is around eight.

Vehicle Routing Problem (VRP) is an important issue that has much used for productivity and efficiency of transportation systems in recent decades. One of the most popular and widely used developments VRP is the vehicle routing problem with simultaneous delivery and pick-up (VRPSPD). In other words, each customer simultaneously receives and sends goods. The proposed procedure is a combination of the three heuristic, nearest neighbor algorithm, cheapest insertions, genetic algorithm. The first two algorithms with a random method provided the initial solution for the third algorithms. A probability function have been developed in the nearest neighbors and cheapest insertions, to construct better solutions; as well as operations proposed for the genetic algorithm to increase the search space and avoiding local optimizationis. The proposed algorithms has implemented on 40 different standard examples. After comparing the results by this algorithm and the best solutions by other algorithms, improvement is observed in 3 of the examples.

Iranian design code like any other design code increases the reliability of a structure by means of multiplying the partial safety factors by load and resistant. The reliability index can be evaluated in order to survey the reliability of structures. In this paper, the reliability index of a beam as an important member of a structure is considered and the effect of the values and coefficient of variation of design parameters on the reliability index is surveyed. Finally, the partial safety factors for different states are proposed. In this paper, a new method based on genetic algorithm (GA) is used to calculate the reliability index. This new method has more efficiency in comparison with the classic methods and the simulation methods such as Monte Carlo. This method does not require the mathematical form of the limit state function and on the other hand, this method takes less computational time in comparison with simulation methods. In structural construction, there are many different design parameters which are random variables. Probability distribution can be considered for each of these random variables. For different statistical data of design parameters, different partial safety factors are needed to optimum design of a beam. However, Iranian design code considers the constant partial safety factors for all different conditions. In case that the exact and specific statistical data of design parameters are available, the structural reliability analysis can be applied for reaching an optimum design. The statistical data of design parameters can be obtained by gathering the statistical data in any country and after that a reliable design code can be obtained based on these statistical data. Because of lack of statistical data of design parameters in Iran, five usual conditions were considered for data and then partial safety factors are calculated.

In dam construction industry, the safety of dam is one of the most important challenges that should be considered in design, construction and operation phase. Recently, use of quantitative risk analysis, as a useful tool in dam safety risk management, is rapidly increasing. In this paper, first, risk assessment methods in dam safety are investigated and ANCOLD guideline for dam safety risk assessment is detailed. Then, as a case study, safety of Goleastan dam, in northeast of Iran, is assessed considering risk analysis approach for upstream flood hazard. For calculating the probability of failure of dam, the various methods were assessed and finally Event Tree Analysis (ETA), as most commonly method in dam safety risk analysis, was used. The number of life losses due to flooding of Golestan dam break is estimated based on USBR methodology, known as DSO-99-06. Finally, according to calculated risk and comparing with different criteria for acceptable risk, it is obvious that the risk of Golestan dam break due to upstream flood is unacceptable and immediate risk reduction measures are necessary.

Based on Iranian Standard 2800, drift of each story for the lateral seismic loading should not exceed the mentioned values. It is stipulated in the Note of this article that in drift calculation, the period of the building can be determined through experimental formula, mentioned in the code or be calculated by the analytical methods. Regarding that experimental base formulas normally give shorter period, so they lead to stronger structures. Application of analytical base period for special moment resisting structure leads to a structure with less weight and strength, which satisfy the criteria and thus is acceptable. In this research, some buildings with special moment resisting regular slender structures are considered and designed twice based on two assumptions, with and without considering the article note. To compare these building, their damage indices and endurance times were calculated through nonlinear three dimensional time-history analyses. Analyses show that, structure designed based on analytical period not only has lighter structure, but also have better seismic behavior and more endurance time under “in” series of ET records.

Incremental dynamic analysis (IDA) is a parametric analysis method that it is used in estimation of structural performance by subjecting the structural model to multiple suitably scaled ground motion records, each scaled to multiple levels of intensity, thus producing several curves of response parameterized by intensity level. Recognizing that IDA of practical structures is computationally demanding, an approximate procedure based on the reduction of the number of ground motions is developed. A methodology based on data envelopment analysis, mathematical programming that can handle large numbers of variables and relations, is proposed to reduce the number of ground motions needed for the production of a reliable median incremental dynamic analysis curve. Theses curves computed by the exact and approximate procedures for two different 4- and 8-story buildings and one set of ground motions are presented. The results demonstrate that the approximate procedure, which uses a limited number of input ground motions, has the error less than about 5%.

In this research, waste stone sludge obtained from slab stone processing from stone washing plants were recycled to Stabilization of clayey soil with lime. Fine-powdered stone sludge was mixed with clay soil and lime. Thus, the effectiveness of using waste stone powder and lime in stabilizing fine-grained clayey soil (CL) was investigated in the laboratory. The soil samples in natural state and when mixed with varying percentages of lime and waste stone powder were used to laboratory tests that included atterberg limits tests, grain size analysis, standard Proctor compaction tests, unconfined compression tests and California bearing ratio tests. The results show significant reduction in plasticity and changed the optimal moisture and maximum dry density of clayey soil with increasing amount of waste stone powder and lime. The results of the unconfined compressive strength tests and California bearing ratio tests show that in the different curing time, the addition of waste stone powder and lime caused an increase in the value of UCS up to 6% waste stone powder content and 7% lime content, and increase in the value of CBR until 6% waste stone powder content and 9% lime content, for further percentages, the value of UCS and CBR decreased.

Piping is a phenomenon that commonly occurs at downstream of hydraulic structures such as earth dams, irrigation channels and drainage network under the influence of upward seepage. Piping is considered as the main mechanism of hydraulic structures failing. In this work an experimental program was set for determination the seepage velocity and piping resistance for unreinforced and reinforced sand silty samples. Two type of fibers (Polyester and Polyethylene terephthalate) with different diameter (0.2 mm and 0.3 mm) was used for preparing reinforced samples. The experimental tests was conducted on samples without and with different fiber content (0.5%, 0.75%, 1% and 1.25%) and fiber length (5, 25, 35 and 50 mm) under different hydraulic heeds in a special designed apparatus. Discharge and seepage velocity of water flow through unreinforced and reinforced samples was measured and calculated and Comparison was made. The results showed that the inclusion of fiber reduces the seepage velocity and increased the hydraulic gradient and piping resistance. Furthermore, increasing of hydraulic gradient and piping resistance is function of fiber content and fiber length.

Provision of ductility has always been of concern in seismic design of structures. However, large variability in connection performance is observed during the recent earthquakes, due to brittle fracture of steel moment frame connections. In this study, Distribution of early fracturing pre-Northridge connections is optimized by genetic algorithm tool to quantify the sensitivity of seismic response of the structures to spatial variation of early fracturing connections for two hazard levels. Also, a non degrading ductile connection is modeled to compare the seismic performance of the structures. Probability assessment is carried out by implementation of incremental dynamic analysis to find the reliability of structures under this condition. Results show that configuration of fracturing connections in beams, in contrast to columns, can significantly affect the collapse capacity of structures.

Few algorithms are available for economic optimization of underground mining area. This is mainly because there are a variety of underground mining methods with various restrictions and conditions and the underground mining parameters are more complex. Therefore, it does not allow the development of general optimization tools, especially, software tools or computer programs. Based on the Global Optimisation for Underground Mining Area (GOUMA) algorithm, a computer program , GOUMA-CP, was developed to implement the mentioned algorithm. GOUMA enjoys a new system of modelling named "Variable Value Economic Model" (VVEM) and benefits from the mathematical proof and provide the true optimal solution according to the conditions and environment it is applied. This paper includes a description of the GOUMA-CP program in details and the corresponding algorithm briefly. This computer program has successfully been applied to optimise underground mining area of a gold mine in Australia.