i-manager's Journal on Structural Engineering (JSTE)


Volume 5 Issue 4 December - February 2017

Research Paper

Analysis of Transmission Towers for Optimal BracingConfiguration

Siddam Srihitha* , B.D.V. Chandra Mohan Rao**
* PG Student, Department of Civil Engineering, VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, India.
** Professor, Department of Civil Engineering, VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, India.
Srihitha, S., and Rao, B.D.V.C.M. (2017). Analysis of Transmission Towers for Optimal Bracing Configuration. i-manager’s Journal on Structural Engineering, 5(4), 1-8. https://doi.org/10.26634/jste.5.4.10383

Abstract

Transmission line towers are designed to meet the increasing demand for electrical energy. In this paper, a selfsupporting transmission line tower with three different types of bracing patterns (W, Y, and XB) is analyzed to obtain an optimal bracing configuration. The transmission tower is modelled and analyzed as a three-dimensional structure in STAAD. Pro V8i. The bracing system is the vital component in transmission line towers which provides lateral load resistance in steel towers. The base width of the tower is taken as one-sixth of the total height of the tower. All the towers considered in this work are of constant height and base width, but of different types of bracing configurations. The tower configuration has been determined by taking into account of all structural and electrical requirements of a tower. The sag, tension for both conductor and ground wire and the wind load at each panel are evaluated. The various loads acting on the tower such as transverse loads, vertical loads, longitudinal loads, and panel loads for various bracing configurations are calculated. The various parameters, such as joint displacements, and the total weight of steel required are evaluated and an optimal bracing configuration has been suggested.

Research Paper

Intercomparison of Probability Distributions using Goodness-of-Fit and Diagnostic Tests for Extreme Value Analysis of Rainfall

Vivekanandan*
*Scientist - B, Central Water and Power Research Station, Pune, Maharashtra, India.
Vivekanandan, N. (2017). Intercomparison of Probability Distributions using Goodness-of-Fit and Diagnostic Tests for Extreme Value Analysis of Rainfall. i-manager’s Journal on Structural Engineering, 5(4), 9-16. https://doi.org/10.26634/jste.5.4.10389

Abstract

Estimation of extreme rainfall for a desired return period is a prerequisite for planning, design and operation of various hydraulic structures, such as dams, bridges, barrages, and storm water drainage systems. Depending on the size and the design-life of the structure, the estimated extreme rainfall corresponding to particular return period is used. This can be computed through Extreme Value Analysis (EVA) of rainfall by fitting probability distributions to the recorded values of annual 1-day maximum rainfall. This paper illustrates the adoption of Extreme Value Type-1, Extreme Value Type-2, 2- parameter Log Normal and Log Pearson Type-3 (LP3) probability distributions in EVA of rainfall for Hissar and Tohana. Based on the applicability, standard parameter estimation procedures, viz., Method of Moments (MoM), Maximum Likelihood Method (MLM), and Order Statistics Approach are used for determination of parameters of distributions. The adequacy on the fitting of probability distributions used in EVA of rainfall is evaluated by applying Goodness-of-Fit (GoF) tests, viz., Anderson-Darling and Kolmogorov-Smirnov. In addition to GoF tests, D-index is employed to evaluate the best suitable probability distribution for estimation of extreme rainfall. The study suggests the LP3 (using MLM) is better suited amongst four probability distributions adopted in EVA for estimation of extreme rainfall for Hissar and Tohana.

Research Paper

Improvement of Bearing Capacity of Soil using Bamboo and Geosynthetics

M. Mamatha* , Suresh Kommu**
* PG Student, Department of Civil Engineering, VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, India.
** Assistant Professor, Department of Civil Engineering, VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, India.
Mamatha, M., and Kommu, S. (2017). Improvement of Bearing Capacity of Soil using Bamboo and Geosynthetics. i-manager’s Journal on Structural Engineering, 5(4), 17-22. https://doi.org/10.26634/jste.5.4.10390

Abstract

When structures have to be constructed on challenging ground conditions, soil reinforcement can be an adaptable technique to improve ground. This paper deals with the experimental and analytical studies carried out to understand the possibility of using naturally available bamboo to increase the bearing capacity of the soft soil. Already existing soil at site may not be always suitable for supporting structures, such as dams, embankment, bridges, and dams. An attempt was made in this project to investigate the mechanism of naturally available bamboo and artificially available geosynthetics placed over soft soil at different depths by performing the CBR test. Thus, in order to predict the settlement accurately underneath the foundation rest on the soil, analysis that are more realistic are necessary, and a comparison can be made between the settlement for reinforced and unreinforced soil conditions. In granular soil deposits, the in situ soil may be very loose and indicate a large elastic settlement and UCS test was conducted to know the shear strength of the soil taken for conducting experiments. This study proposes a cost effective ground improvement technique in soft soils, an alternative to geotextile and geogrids.

Research Paper

Effect of Mass of Moving Load on Dynamic Response of a Simply Supported Railway Bridge

Rohit Kumar Mittal* , Vutukuru Krishna Sai**, Pabitra Ranjan Maiti***
*-** PG Scholar, Department of Civil Engineering, Indian Institute of Technology (BHU), Varanasi, India.
*** Associate Professor, Department of Civil Engineering, Indian Institute of Technology (BHU), Varanasi, India.
Mittal, R.K., Sai, V.K., and Maiti, P.R. (2017). Effect of Mass of Moving Load on Dynamic Response of a Simply Supported Railway Bridge. i-manager’s Journal on Structural Engineering, 5(4), 23-29. https://doi.org/10.26634/jste.5.4.10391

Abstract

Moving loads have great impact on structures. On one side, concentrated load moving with high speed induces dynamic impact on structures, influencing their working state and service life. On the other side, these vibrations of the bridge caused due to moving load in turn affect the running stability and safety of moving load.Only in case of short span bridges when mass of moving load is comparable to mass of the bridge, moving load is also taken into account to perform dynamic analysis of the bridge. Displacement response to variation in speed of moving load at different damping of the bridge are plotted and compared when deflection is to be considered at different locations on the bridge. It is observed that when concentrated load moves with critical speed, maximum deflection takes place at mid span of the bridge. When damping is taken into account, a point of singularity occurs below which derived governing equation holds good. The effect of mass of moving load on the dynamic response of the bridge is studied and it is concluded that governing equation in both cases, i.e. without considering the mass of moving load and with consideration of mass of moving load, overlap each other.

Research Paper

Dynamic Analysis of RC Chimneys

T. Sharvani* , B.D.V. Chandra Mohan Rao**
* PG Student, Department of Civil Engineering, VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, India.
** Professor, Department of Civil Engineering, VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, India.
Sharvani, T., and Rao, B.D.V.C.M (2017). Dynamic Analysis of RC Chimneys. i-manager’s Journal on Structural Engineering, 5(4), 30-37. https://doi.org/10.26634/jste.5.4.11389

Abstract

Reinforced Concrete chimneys are commonly used in major industries and power plants .Chimneys are slender structures, and loads acting on the chimney are self weight, wind loads, earthquake loads, and temperature loads. The designs of chimneys are normally governed by wind or earthquake loads. The dynamic characteristics of the RC chimney will vary in a wider range with respect to the aspect ratio (ratio of height to longitudinal section). In this paper, Dynamic analysis of an RC chimney in zone III is carried out by Response spectrum analysis as per IS 1893:2005 for different top and bottom diameters of the chimney and varying thickness of the shell using software SAP2000 version 18.0.1. Grade of concrete used is M25. The influence of various geometric parameters H/D and D/T ratios on the modal parameters and dynamic response of the structure, i.e., top displacement, fundamental frequencies, and Base shear are investigated.

Research Paper

Assessment of Resonance Effects on Railway Bridges under Moving Loads

Anand* , R. S. Sonparote**
* Assistant Professor, Department of Civil Engineering, Shri Ramdeobaba College of Engineering and Management, Nagpur.
** Associate Professor, Department of Applied Mechanics, Visvesvaraya National Institute of Technology, Nagpur.
Gharad, A.M., and Sonparote, R.S. (2017). Assessment of Resonance Effects on Railway Bridges under Moving Loads. i-manager’s Journal on Structural Engineering, 5(4), 38-47. https://doi.org/10.26634/jste.5.4.11390

Abstract

In this work, a Finite Element (FE) approach to assess the dynamic response of simply supported railway bridges subjected to loads moving with a constant velocity was studied. Euler-Bernoulli beam was used to simulate the bridge. Verification of the dynamic response using the Finite Element Method was done with respect to the available analytical solutions. Post-validation, a two-span continuous beam was analyzed using FE approach. A three-dimensional model, both for simply supported and two-span continuous bridges, formulated in the time domain to study the dynamic response due to passage of moving loads was carried out. 8 noded solid (brick) elements were used to simulate the sleepers, ballast and bridge; whereas the rails were modeled using frame elements. A parametric study to evaluate the resonance response of the 3D railway bridge structure was conducted.