scholarly journals Seismic performance of existing water tank after condition ranking using non-destructive testing

2019 ◽  
Vol 11 (4) ◽  
pp. 395-410 ◽  
Author(s):  
Chittaranjan B. Nayak ◽  
Sunil B. Thakare
Keyword(s):  
Seismic Vulnerability ◽  
Seismic Retrofit ◽  
Condition Index ◽  
Mode Shapes ◽  
Natural Phenomenon ◽  
Water Tank ◽  
Base Shear ◽  
Elevated Water ◽  
Non Destructive

Abstract There has been a collaborative attempt to address the seismic vulnerability of existing structures in India after an earthquake in Bhuj, Gujarat, in 2001. Seismic diagnosis and seismic retrofit for the existing tanks have become a remarkable issue to be worked since deterioration is a cosmopolitan and natural phenomenon. It is important to know the exact reason for distress and type of distress. To manage such issues, a proper method of repair and rehabilitation with detailed plans and methodology is required. This paper is aimed at evolving systematic investigation metrology for condition ranking procedure based on the analytical hierarchy process (AHP) and strengthening by various retrofitting strategies. For that case study, an existing elevated water tank is considered, which was designed according to state of the art over 40 years ago as per old Indian Standard (IS) code. The ranking assessment of the elevated service reservoir was carried out using different non-destructive tests (NDTs). DER, i.e., degree (D), extent (E) and relevancy (R) rating technique was employed to find out the condition index of the elevated service reservoir (ESR). After finding the condition ranking of the existing structure, an analysis was carried out using SAP 2000 to find the present-day seismic requirements using IS codes. After knowing the seismic demand of the water tank, various retrofitting methods were adopted for improving the drift capacity and flexural capacity of the structure. The results were finally used to address some of the critical issues of the seismic response of the retrofitted structure in terms of a time period, mode shapes, base shear, displacement, acceleration, and velocity. From the case study result of seismic retrofit for the existing elevated water tank, it is confirmed that a relatively simple seismic retrofit method is effective to keep the tank functional after an earthquake.

scholarly journals Use ofIn-SituDynamic Measurements to Calibrate Analytical Models of RC-Elevated Water Tanks

2012 ◽  
Vol 19 (5) ◽  
pp. 903-914
Author(s):  
H.M. Lopes ◽  
C.S. Oliveira
Keyword(s):  
Water Supply ◽  
Analytical Models ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Water Supply Systems ◽  
Water Tank ◽  
Analysis And Design ◽  
Elevated Water ◽  
Water Tanks

Before establishing the priority settings for the reduction of seismic risk of water supply infrastructures, it is necessary to understand the dynamic behavior of elevated water tanks, which are components of those infrastructures. Among other information, the main frequencies of vibration of these structures must be estimated and the analytical models used in their analysis and design should reproduce the frequency values obtained by in-situ dynamic tests. This work focuses exclusively on reinforced concrete (RC) elevated water tanks (200–750 m^3 of water at heights of 30–40 m), which are very common structures in the water supply systems in Portugal since the mid XXth century. This type of structures can also be seen in many regions around the world. First, a nationwide survey was conducted to determine the most common typologies in the country in terms of structural layout. Second, an in-situ campaign using ambient vibration as input was performed for a group of selected structures to determine the main frequencies of vibration and to identify modal shapes and damping values. Third, a finite element model of several different typologies was developed using the water simply as a concentrated mass at the top; the elastic properties of the model of the structure including the foundation were calibrated, so that the frequencies of various mode shapes obtained by the analytical model would match the frequencies of the real structure. Finally, an expression was derived to estimate the fundamental frequency of a group of elevated water tank typologies based on the total mass at the top of the supporting structure, which include the water, the global lateral stiffness, and the height of the tank. This study, providing important information on the frequencies of vibration of RC-elevated water tanks, contributes in a definite way to the analysis and design of such water tanks.

scholarly journals Seismic Analysis of Circular Elevated Water Tank Designed by Indian Standard and European Standard Code

2021 ◽  
Vol 9 (10) ◽  
pp. 1638-1641
Author(s):  
Siddhnath Verma
Keyword(s):  
Soft Soil ◽  
Soil Conditions ◽  
Water Tank ◽  
Base Shear ◽  
European Standard ◽  
Soil Medium ◽  
Seismic Zones ◽  
Standard Code ◽  
Hard Soil ◽  
Elevated Water

Abstract: Elevated water tank is used for storage of water which is used for distribution to the public at certain pressure head. In high seismic zones the safety of water tank becomes point of great concern which in case of failure becomes very hazardous for public because of deficiency of water for public use and difficulty in putting fire away caused by earthquake. The water tank must be designed as much strong so that it can perform during and after earthquake without failing. The aim of this study is to design the elevated water tank as per Indian standard code and European standard code on ETABS software. In this study an elevated circular water tank of 35 m3 capacity is being designed in seismic zone III as per IS code and spectrum zone II as per Euro code for hard soil, medium soil and soft soil conditions. During analysis of tank the values of base moment, base shear, storey displacement and storey drift is being obtained and compared in both seismic zones for hard soil, medium soil and soft soil. Keywords: base shear, base moment, ETABS, elevated water tank.

Non-Linear Time History Analysis of an Elevated Water Tank

2021 ◽  
Vol 9 (VI) ◽  
pp. 4327-4334
Author(s):  
Mr. Rohit Kiran Chaudhari
Keyword(s):  
Reinforced Concrete ◽  
Seismic Analysis ◽  
Linear Time ◽  
Time History ◽  
Seismic Energy ◽  
Soil Condition ◽  
Mode Shapes ◽  
Water Tank ◽  
Elevated Water ◽  
Water Tanks

It was discovered that reinforced concrete elevated water tanks with frame staging outperformed reinforced concrete elevated water tanks with shaft staging in terms of seismic resistance. These can be due to the frame staging's seismic energy absorption capability. As a result, the primary goal of this research is to better understand the seismic behavior and performance characteristics of elevated water tanks with frame staging. Furthermore, when compared to other shapes, circular tanks have the smallest surface area for a given tank size. As a result, the amount of material needed for a circular water tank is less than for other shapes. As a result, a circular water tank was chosen, and seismic analysis of elevated RC circular water tanks was carried out according to IITK-GSDMA guidelines, with the behavior of the water tank analysed for various parameters such as zone factor, soil condition, and different staging heights. SAP 2000 was used to determine the structure's modal characteristics (mode shapes and modal participation mass ratio).

scholarly journals Performance of elevated water tank staging with base isolation under blast loading

2021 ◽  
Vol 309 ◽  
pp. 01134
Author(s):  
Boda Balaraju ◽  
Atulkumar Manchalwar
Keyword(s):  
Base Isolation ◽  
Linear Time ◽  
Time History ◽  
Water Tank ◽  
Base Shear ◽  
Isolation Technique ◽  
Underground Blast ◽  
Base Isolator ◽  
Fixed Base ◽  
Elevated Water

In this present study aims to evaluate the performance of base isolation device under different intensity blast induced ground excitations for an elevated water tank staging. In this study mainly focused to improve the performance of the base isolator and minimize the damage of the structure. To know the performance of base isolator two models are considered one is fixed base model and another one is supported with base isolator model for both non-linear time history analysis is carried out with the help of SAP 2000 software subjected to four different underground blast intensities. From the analysis, it is observed that by using base isolator supported model structural responsive parameters such as base shear, top storey accelerations are efficiently reduced when compared to the fixed base structure. Hence it is proved that adopting base isolation technique we considerably reduce the damage of the structure subjected to underground blast vibrations.

scholarly journals Seismic Analysis of Circular Water Tank Designed by Indian Standard Code and Euro Code

2021 ◽  
Vol 9 (10) ◽  
pp. 635-638
Author(s):  
Siddhnath Verma
Keyword(s):  
Seismic Analysis ◽  
Soft Soil ◽  
Soil Conditions ◽  
Water Tank ◽  
Base Shear ◽  
Seismic Behaviour ◽  
Soil Medium ◽  
Standard Code ◽  
Elevated Water ◽  
Water Tanks

Abstract: Water tanks are widely used for storage of drinking water. Water tanks and especially the elevated water tanks are structures of high importance which are considered as main lifeline elements that should be capable of keeping the expected performance i.e. operation during and after earthquakes. In this research paper, the analysis of the seismic behaviour of the elevated circular water tank by Indian standard code and Euro code is carried being carried out. The analysis is carried out on 35 cubic meter capacity elevated circular water tank in zone III and spectrum zone II and on three different soil conditions i.e. hard soil, medium soil and soft soil using ETABS software as per Indian standard code and European standard code. The results of base shear, base moment, storey displacement and storey drift are obtained from both codal provisions. Keywords: Elevated water tank, Seismic response, Etabs, Base shear, Base moment

scholarly journals Structural Operativity Evaluation of Strategic Buildings through Finite Element (FE) Models Validated by Operational Modal Analysis (OMA)

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3252
Author(s):  
Dora Foti ◽  
Nicola Ivan Giannoccaro ◽  
Vitantonio Vacca ◽  
Michela Lerna
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Seismic Vulnerability ◽  
Element Model ◽  
Efficiency Index ◽  
Small Error ◽  
Operational Modal Analysis ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Non Destructive

In this paper, a non-destructive technique based on the monitoring of the environmental vibrations of two strategic buildings by positioning accelerometers in well-defined points was used for fixing their dynamic behavior. The accelerometers measurements were elaborated through Operational Modal Analysis (OMA) techniques, in order to identify natural frequencies, damping coefficients, and modal shapes of the structure. Once these parameters have been determined, a numerical model calibrated on the identified frequencies and verified on the corresponding mode shapes was created for each building. The structural operational efficiency index of the buildings was determined by using the Seismic Model Ambient Vibration (SMAV) methodology, which allows us to evaluate their seismic vulnerability. The results obtained from the experimental analysis (on three different tests for each analyzed building) concern the frequencies and the modal shapes of the structure. They have been compared to the results of the finite element model, with a very small error, indicating a good quality of the analysis and also the possibility of using directly well-tuned models for verifying the structural operating indices.

Failure Analysis Case Study of a 1.5 Meter Space Flex Harness

2017 ◽  
Author(s):  
Erick Kim ◽  
Kamjou Mansour ◽  
Gil Garteiz ◽  
Javeck Verdugo ◽  
Ryan Ross ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Failure Modes ◽  
Field Of View ◽  
Area Of Interest ◽  
Air Stream ◽  
Novel Method ◽  
Temperature Controlled ◽  
Non Destructive ◽  
Failure Site

Abstract This paper presents the failure analysis on a 1.5m flex harness for a space flight instrument that exhibited two failure modes: global isolation resistances between all adjacent traces measured tens of milliohm and lower resistance on the order of 1 kiloohm was observed on several pins. It shows a novel method using a temperature controlled air stream while monitoring isolation resistance to identify a general area of interest of a low isolation resistance failure. The paper explains how isolation resistance measurements were taken and details the steps taken in both destructive and non-destructive analyses. In theory, infrared hotspot could have been completed along the length of the flex harness to locate the failure site. However, with a field of view of approximately 5 x 5 cm, this technique would have been time prohibitive.

A novel tuned mass-conical spring system for passive vibration control of a variable mass structure

2021 ◽  
pp. 107754632110004
Author(s):  
Sanjukta Chakraborty ◽  
Aparna (Dey) Ghosh ◽  
Samit Ray-Chaudhuri
Keyword(s):  
Variable Mass ◽  
Design Procedure ◽  
Time History ◽  
Tuned Mass Damper ◽  
Water Tank ◽  
Mass System ◽  
Mass Damper ◽  
Linear Spring ◽  
Spring System ◽  
Elevated Water

This article presents the design of a tuned mass damper with a conical spring to enable tuning to the natural frequency of the system at multiple values, as may be convenient in case of a system with fluctuations in the mass. The principle and design procedure of the conical spring in the context of a varying mass system are presented. A passive feedback control mechanism based on a simple pulley-mass system is devised to cater to the multi-tuning requirements. A design example of an elevated water tank with fluctuating water content, subjected to ground excitation, is considered to numerically illustrate the efficiency of such a tuned mass damper associated with the conical spring. The conical spring is designed based on the tuning requirements at different mass conditions of the elevated water tank by satisfying the allowable load bearing capacity of the spring. Comparisons are made with the conventional passive tuned mass damper with a linear spring tuned to the full tank condition. Results from time history analysis reveal that the conical spring-tuned mass damper can be successfully designed to remain tuned and thereby achieve significant response reductions under stiffening conditions of the primary structure, whereas the linear spring-tuned mass damper suffers performance degradation because of detuning, whenever there is any fluctuation in the system mass.

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