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Volume 7 (1); 25 Jan, 2017


altResearch Paper

Assessment of Static and Dynamic Behavior of Emarat Earth Dam by Finite Difference Method.

Nazari Giglou A, Panahi A, Solari L, Bombar G.

J. Civil Eng. Urban., 7(1): 01-11, 2017; pii:S225204301700001-7

Abstract

Behaviour of earth dams during the construction, at the end of construction, and during the first dewatering is very important and it is necessary to ensure the safety of the dam in these three stages. In recent years, a number of different approaches have been developed to solve the geotechnical problems including static and dynamic analysis of earth dams. Emarat dam is an earthen dam with a clay core on the Darehrood River, one of the branches Aras river constructed at a distance of 100 km from the Meshkinshar city. In this study, using FLAC2D software and the finite difference method, the strength characteristics of the body and foundation materials of this earth dam have been identified and the static and dynamic behaviour of Emarat dam during the construction and inundation has been investigated. Regarding to achieved analysis it can be declared that Emarat earth dam has been statically stable during the critical process of ending of construction, dewatering stage and after dewatering stage. Considering to input earthquake which its frequency is close to Emarat earth dam frequency, it is dynamically stable.
Keywords: Emarat Dam, Static Analysis, Dynamic Analysis, Numerical Methods, FLAC2D.

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altResearch Paper

Prediction of Seasonal and Annual Rainfall using Order Statistics Approach of Gumbel and Frechet Distributions.

Vivekanandan N.

J. Civil Eng. Urban., 7(1): 12-17, 2017; pii:S225204301700002-7

Abstract

Prediction of seasonal and annual rainfall for a river basin has utmost importance for planning of irrigation and drainage systems as also for command area development. This can be achieved by deterministic, conceptual and probabilistic methods. This paper illustrates the use of Gumbel and Frechet probability distributions for modelling seasonal and annual rainfall for Krishna and Godavari river basins. Lieblein technique based on order statistics approach is used for determination of parameters of the distributions. Model performance indicators such as correlation coefficient, model efficiency and root mean square error are used for the selection of suitable distribution for modelling seasonal and annual rainfall. The study suggests the Gumbel distribution is better suited for prediction of seasonal and annual rainfall for Krishna and Godavari river basins.
Keywords: Correlation, Frechet, Gumbel, Mean square error, Model efficiency, Rainfall

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alt

Research Paper

Finite Element Modeling of Connections to Concrete-Filled Steel Columns under Fire.

Ashrafi HR, Beiranvand P, Dadgar MR and Dadgar S.

J. Civil Eng. Urban., 7(1): 18-24, 2017; pii:S225204301700003-7

Abstract

Concrete-filled steel tubular columns have been extensively used in structures, owing to that they utilize the most favorable properties of both of constituent materials, ductility, large energy-absorption capacity, and good structural fire behavior. Concrete inside the steel tube enhances the stability of the steel tube, and the steel tube in turn provides effective lateral confinement to the concrete. Furthermore, the fire resistance of CFT columns is higher than that of hollow steel tubular columns, external protection being not needed in most cases. During a fire, the steel tube acts as a radiation shield to the concrete core and a steam layer in the steel-concrete boundary appears. This paper employs the general finite element software ABAQUS to numerically model the behavior of restrained structural subassemblies of steel beam to concrete filled tubular (CFT) columns and their joints in fire. The simulations were conducted using 3-D brick elements to enable detailed structural behavior to be obtained. For validation, this paper compares the simulation and test results for the three fire tests using reverse channel connection recently conducted at the University of Manchester. This comparison demonstrates that the 3-D finite element model is able to successfully simulate the fire tests. Afterwards, the validated finite element model was used to conduct a preliminary numerical study to investigate the feasibility of changing some of the connection details to enhance survivability of the structure in fire. Specifically, this investigation concentrated on developing connection methods to enable catenary action in the connected beam to be more fully developed. An example is to develop a hybrid flush/extended endplate and flexible endplate connection in which the tension part of the connection uses a flush/extended endplate for increased tensile resistance but the compression part of the connection uses a flexible endplate for improved ductility. It has been found that, without additional cost, using a hybrid extended/flexible endplate connection to replace a flush endplate connection has the potential to enable the connected beam to survive significantly increased temperature.
Key words: Concrete-Filled Steel Columns, Reverse Channel, Finite Element, Endplate.

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