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


Volume 12 Issue 3 October - December 2023

Research Paper

Assessment of Uncertainty of Error in Design Flood Estimates Using 2-Parameter Log Normal Distribution

N. Vivekanandan*
Hydrometeorology Division, Central Water and Power Research Station, Pune, Maharashtra, India.
Vivekanandan, N. (2023). Assessment of Uncertainty of Error in Design Flood Estimates Using 2-Parameter Log Normal Distribution. i-manager’s Journal on Structural Engineering, 12(3), 1-8. https://doi.org/10.26634/jste.12.3.20374

Abstract

Estimation of design flood is formed as a basis for planning and management of civil engineering construction especially hydraulic structures such as water use and flood control structures. The dimensions and capacity of the buildings depend on flood magnitude for a given return period that may have some uncertainty due to model error. This can be achieved through Flood Frequency Analysis (FFA) that involves fitting probability distribution to the series of Annual Maximum Discharge (AMD) data. In this paper, a study on assessment of uncertainty of error in design flood estimates was carried out by fitting Method of Moments (MoM), Maximum Likelihood Method (MLM) and method of L- Moments (LMO) of 2- parameter Log Normal (LN2) distribution to the series of AMD data for river Tapi at Prakasha barrage. The selection of best fit method of LN2 was made through Goodness-of-Fit (GoF) tests viz., Chi-Square and Kolmogorov-Smirnov, and Model Performance Indicators (MPIs) such as correlation coefficient, root mean absolute error and root mean squared error. GoF tests results confirmed the suitability of all three methods of LN2 for estimation of Peak Flood Discharge (PFD). The results indicated that the predicted PFD by MLM is closer to the observed data. From FFA results, it was witnessed that the standard error on the estimated PFD by MoM is minimum than those values of MLM and LMO. The outcomes of FFA results were weighed with MPIs and found that MLM is better suited amongst three methods of LN2 for estimation of PFD at Prakasha barrage.

Research Paper

The Impact of Plan Irregularity on Multistory Building Response: A Pushover Analysis

Madan Chandra Maurya*
Department of Civil Engineering, Madan Mohan Malaviya University of Technology, Uttar Pradesh, India.
Maurya, M. C. (2023). The Impact of Plan Irregularity on Multistory Building Response: A Pushover Analysis. i-manager’s Journal on Structural Engineering, 12(3), 9-21. https://doi.org/10.26634/jste.12.3.20512

Abstract

Structural irregularity often stems from a combination of plan and elevation irregularities, as perfect regularity is seldom achieved in real structures. Defining structural irregularities is challenging due to their varying nature. While scientific literature tends to separate plan and elevation irregularities, there's a need to understand the behavior of real structures that possess plan irregularities. This paper investigates the impact of plan irregularities on multi-story building responses through pushover analysis. The study aims to evaluate various parameters such as capacity curves, performance levels, story drifts, and displacements for irregular building models compared to regular ones. Four and eight-story buildings are designed according to Indian standards, and nonlinear static analysis is conducted using a plastic hinge model. Plastic hinges are assigned at possible failure locations, and pushover analysis is performed. Eccentricity is incorporated by shifting the position of live loads and adjusting column dimensions on both sides of the axis of symmetry at eccentricity values of 10%, 20%, 30%, and 40%. Displacement-controlled pushover analysis is conducted, and pushover curves are obtained in the X direction. The performance of building models is compared with a regular reference frame. Capacity curves, performance points, and story response plots are analyzed using ETABS 9.7.0. The results indicate a reduction in base shear capacity with increasing irregularity, with eccentricity showing a greater effect than soft story irregularity. Irregularity also influences the height-wise variation of story drifts differently.

Research Paper

Static and Vibration Analysis of Reinforced Cement Concrete Cellular Beams: A Three-Dimensional Study

Manisha P.* , Harish G.**, Gowtham Raj Ch.***, Chandrasekhar K. N. V.****
*-**** Department of Civil Engineering, CVR College of Engineering, Hyderabad, Telangana, India.
Manisha, P., Harish, G., Raj, Ch. G., and Chandrasekhar, K. N. V. (2023). Static and Vibration Analysis of Reinforced Cement Concrete Cellular Beams: A Three-Dimensional Study. i-manager’s Journal on Structural Engineering, 12(3), 22-33. https://doi.org/10.26634/jste.12.3.20518

Abstract

This paper presents an analysis of Reinforced Cement Concrete (RCC) cellular beams, focusing on both static and dynamic aspects. The study investigates the behavior of RCC cellular beams under varying loads, including dead weight, superimposed loads, and environmental factors like wind. It addresses the essential characteristics of dynamic problems compared to static loading scenarios, emphasizing the influence of time-varying loads on structural response. The research methodology involves the design and analysis of a simply supported RCC beam with circular openings, utilizing advanced computational tools such as RISA 3D®. The study outlines the process of modeling, including the design of circular openings and reinforcement details. It also discusses the theoretical background, including the strut and tie model of concrete, which is essential for understanding the structural behavior. The paper presents the results of static and vibrational analysis, including stress distribution, mode shapes, and fundamental frequencies of vibration. The analysis evaluates the performance of RCC cellular beams, considering factors such as stress concentrations, principal stresses, shear stresses, and Von Mises stresses.

Research Paper

Pumice as a Coarse Aggregate Substitute for Lightweight Concrete: Strength and Density Assessment

M. Shaju Pragash*
Department of Civil Engineering, Ponjesly College of Engineering, Nagercoil, India.
Pragash, M. S. (2023). Pumice as a Coarse Aggregate Substitute for Lightweight Concrete: Strength and Density Assessment. i-manager’s Journal on Structural Engineering, 12(3), 34-41. https://doi.org/10.26634/jste.12.3.20517

Abstract

This paper investigates the feasibility of using pumice as a substitute for coarse aggregate in lightweight concrete, focusing on its strength and density characteristics. A significant drawback of conventional concrete lies in its substantial dead load, rendering it economically inefficient as a structural material due to its high self-weight. Lightweight concrete, characterized by a lower density, addresses this concern by reducing dead loads and enhancing thermal insulation. This research focuses on achieving density reduction by partially replacing coarse aggregate with pumice in concrete of grade M20. The study aims to assess the structural viability of lightweight pumice concrete by determining its cube compressive strength and split-tensile strength with a target density of less than 1800 kg/m³. Various proportions of pumice substitution ranging from 0% to 20%, 40%, and 60% are investigated. The primary objective is to assess the compressive and split tensile strengths of lightweight concrete specimens. Comparative analysis with traditional concrete aims to identify the most advantageous substitution percentage that offers superior strength while meeting structural requirements.

Review Paper

Masonry Infill in Structural Analysis: Effects on Seismic Performance

S. D. Doye*
Yeshwantrao Chavan College of Engineering, Nagpur, India.
Doye, S. D. (2023). Masonry Infill in Structural Analysis: Effects on Seismic Performance. i-manager’s Journal on Structural Engineering, 12(3), 42-49. https://doi.org/10.26634/jste.12.3.20514

Abstract

In structural analysis, masonry infill is commonly regarded as a non-structural component. However, understanding the true behavior of a structure requires incorporating the effects of masonry infill in seismic evaluations. This paper reviews the effects of masonry infill on seismic performance through analyses including pushover analysis, time history analysis, response spectrum analysis, linear static analysis, and eigenvalue analysis. Ten research papers were reviewed, covering different aspects of masonry infill effects on structures of varying configurations and seismic zones. Results indicate that including masonry infill reduces the fundamental time period of vibration and storey displacement while increasing the base shear compared to bare frame structures. This comprehensive review underscores the importance of considering masonry infill in structural analysis to enhance seismic performance.