scholarly journals Development of Rocking Isolation for Response Mitigation of Elevated Water Tanks under Seismic and Wind Hazards

2020 ◽  
Vol 2020 ◽  
pp. 1-26
Author(s):  
Hassan Alemzadeh ◽  
Hamzeh Shakib ◽  
Mohammad Khanmohammadi
Keyword(s):  
Equations Of Motion ◽  
Water Supply Systems ◽  
Base System ◽  
Tall Structures ◽  
First Case ◽  
Wind Hazards ◽  
Fixed Base ◽  
Tank System ◽  
Elevated Water ◽  
Water Tanks

Elevated water tanks are categorized as strategic components of water supply systems in modern urban management. Past earthquake events have revealed the high vulnerability of these structures. This paper investigates the development of rocking isolation (RI) to these structures as a response mitigation technique. Using an analytical approach, a dynamic model is developed for two isolation cases: (1) at the pedestal base and (2) under the tank. The model incorporates a simplified analogy for simulating the liquid-tank system which is modified for a tank under rocking motions. Based on the dynamics of rocking structures, the equations of motion, impact, and uplift transitions are derived. Then, free vibration and seismic response history analyses are carried out on a sample structure. Discussions are made on the effect of RI on the dynamic and seismic responses of the pedestal and components of the liquid-tank system. Effects of various RI cases, pedestal heights, and tank filling levels are studied for a group of structures excited by an ensemble of ground motions. Considering that the system may be vulnerable to other lateral loadings, the combined effects of seismic and wind hazards are also studied. The wind loads are assumed to act statically and simultaneously with the seismic excitations. Results show that the first case of RI decreases the acceleration demands of mid-rise and tall structures, thus lowering the structural demands to 50% of the fixed-base system. However, the second case of RI has almost no effect on the performance of the system, upgrading only the response of mid-rise structures. Both RI cases also aggravate the wave oscillations and increase the freeboard requirements. Finally, while the combined seismic and wind hazards have almost no effect on the operational performances, the force demands of the structures are increased by 10%.

scholarly journals Serviceability analysis of piled foundations supporting tall structures

2021 ◽  
Author(s):  
Maria Iovino ◽  
Raffaele Di Laora ◽  
Luca de Sanctis
Keyword(s):  
Coupling Effect ◽  
Pile Group ◽  
Mathematical Framework ◽  
Moment Capacity ◽  
Tall Structures ◽  
Pile Interaction ◽  
Elevated Water ◽  
The Moment ◽  
Water Tanks ◽  
Piled Foundations

AbstractPile foundations supporting tall structures, such as wind turbines, chimneys, silos, elevated water tanks or bridge piers, are subjected during their life span to remarkably eccentric loads. These may lead to significant rotations which, however, cannot exceed the limiting values corresponding to the safe operation of the structure. A physically motivated mathematical framework aimed at the prediction of the serviceability performance of such kind of structures is herein presented and discussed. Piles are idealized as uniaxial nonlinear elements characterized by two yielding loads, one in compression and one in uplift, while pile-to-pile interaction effects are modeled by means of superposition, through an approximate solution. The axial load–moment capacity of the pile group is preliminary determined from a recent closed form, exact solution based on upper and lower bound theorems, allowing the analysis to be performed under load control. The model is capable of accounting for the dependence of the moment–rotation response from the dead load of the structure and the ‘coupling effect’ between generalized loads and displacements. The prediction performance of the proposed calculation method is validated against both numerical and experimental benchmarks. Finally, a parametric study allowed to assess the importance of pile-to-pile interaction on the foundation response under eccentric loads.

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 Elevated Water Tank

2019 ◽  
Vol 8 (12S2) ◽  
pp. 271-276
Keyword(s):  
Water Treatment ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Water Tank ◽  
Elevated Water ◽  
Water Tanks ◽  
The Way

Water tanks are the capacity booths for putting away water. Raised water tanks are built to be able to deliver required head with the purpose that the water will movement affected by gravity the development exercise of water tanks is as antique as enlightened guy. The water tanks project has an firstrate want as it serves ingesting water for amazing populace from exceptional metropolitan urban groups to the little population dwelling in cities and towns. The smaller than ordinary project is led for a time of 15 days to have total all the way right down to earth information on unique tactics and issues appeared within the field. An change issue like construction factors, layout Parameters, information of Formwork, information of aid, process of Water treatment Plant and Execution had been controlled over the span of our smaller than regular undertaking."improved water tanks" via raising water tank, the enlargement upward push makes a conveyance strain at the tank outlet. The profile of water tanks begins offevolved with the utility parameters, consequently the type of materials applied and the form of water tank become directed by way of approach of those factors: 1. Vicinity of the water tank (inner, out of doors, over the floor or underground). 2. Volume of water tank need to preserve. 3. What the water may be utilized for? Four. Temperature of territory wherein might be located away, fear for solidifying. Five. Weight required conveying water. 6. How the water to be conveys to the water tank. 7. Wind and quake plan contemplations allow water tanks to endure seismic and excessive wind occasions

scholarly journals Steady and unsteady flow of non-newtonian fluid in curved pipe with triangular

2006 ◽  
Vol 3 (3) ◽  
pp. 470-480
Author(s):  
Baghdad Science Journal
Keyword(s):  
Unsteady Flow ◽  
Pressure Gradient ◽  
Secondary Flow ◽  
Cross Section ◽  
Numerical Study ◽  
Equations Of Motion ◽  
Curved Pipe ◽  
First Case ◽  
Stable Flow ◽  
Flow Cross

This paper deals with numerical study of the flow of stable and fluid Allamstqr Aniotina in an area surrounded by a right-angled triangle has touched particularly valuable secondary flow cross section resulting from the pressure gradient In the first case was analyzed stable flow where he found that the equations of motion that describe the movement of the fluid

Experimental Study on Vertical Base-Isolated System with Disk Spring

2012 ◽  
Vol 166-169 ◽  
pp. 788-792
Author(s):  
Yamin Zhao ◽  
Jingyu Su ◽  
Ming Lu
Keyword(s):  
Shaking Table ◽  
Base System ◽  
Performance Tests ◽  
Shaking Table Tests ◽  
Seismic Responses ◽  
Vertical Stiffness ◽  
Disk Spring ◽  
Fixed Base ◽  
Structural Responses ◽  
Vertical Base

A new vertical isolator designed by disk spring, called combined disk spring bearing (DSB), is introduced in this paper. DSB is composed of one main disk spring bearing and eight secondary disk spring bearings. Performance tests show that DSB had good property of variable vertical stiffness and high vertical damping. Then, the effectiveness of DSB vertical base-isolated devices in reducing structural responses caused by earthquakes through a series of 1/2 scale shaking table tests. are conducted to study the seismic responses of the and the DSB vertical-isolated system. Compared with the fixed-base system, experimental results show that the DSB vertical-isolated system can isolate vertical earthquake energy remarkably. Large displacement of the DSB vertical-isolated system occurred on the isolation layer, and the inter-story deformation of the superstructure changed slightly. The acceleration responses of DSB vertical-isolated system decreased more than 50% and the displacement responses decreased more than 40% at 0.4g PGA, which confirmed that DSB could decrease the seismic responses effectively.

Study of Pushover Analysis on RC Framed Structure with Underground Structure Considering the Effects of Soil Structure Interaction

2020 ◽  
Vol 8 ◽  
pp. 22-29
Author(s):  
Nasala Dongol ◽  
Prachand Man Pradhan ◽  
Suman Manandhar
Keyword(s):  
Soil Structure ◽  
Response Spectrum ◽  
Underground Structure ◽  
Pushover Analysis ◽  
Standard Penetration Test ◽  
Soil Structure Interaction ◽  
Base System ◽  
Building Site ◽  
Structure Interaction ◽  
Fixed Base

This study states that the effects of soil structure interaction on the Reinforced Concrete (RC) framed structures is directly influenced by the soil properties of the site. Here, one preexisting structure is taken for the study. The building is a hospital building with two underground basements. Taking into account the actual soil condition of building site, this study provides idea on the soil structure interaction on the structure The properties of springs are calculated from different standard penetration test (SPT) values, Poisson’s ratio and elasticity of soil along the depth of the soil. Entire soil-foundation-structure system is modelled and analyzed using spring approach. Static analysis, response spectrum analysis and pushover analysis (PA) are done in order to find the variations in natural periods, base shears and deflections of the structures by incorporating soil flexibility as compared to structures with conventional fixed base. Pushover analysis is done to evaluate the performance of the structure when modelled in fixed base and spring base system.

scholarly journals A dynamical system analysis of f(R,T) gravity

2016 ◽  
Vol 13 (09) ◽  
pp. 1650108 ◽  
Author(s):  
Behrouz Mirza ◽  
Fatemeh Oboudiat
Keyword(s):  
Dynamical System ◽  
Dynamical Systems ◽  
Equation Of State ◽  
System Analysis ◽  
Equations Of Motion ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Future Singularity ◽  
First Case ◽  
Stress Energy

We investigate equations of motion and future singularities of [Formula: see text] gravity where [Formula: see text] is the Ricci scalar and [Formula: see text] is the trace of stress-energy tensor. Future singularities for two kinds of equation of state (barotropic perfect fluid and generalized form of equation of state) are studied. While no future singularity is found for the first case, some kind of singularity is found to be possible for the second. We also investigate [Formula: see text] gravity by the method of dynamical systems and obtain some fixed points. Finally, the effect of the Noether symmetry on [Formula: see text] is studied and the consistent form of [Formula: see text] function is found using the symmetry and the conserved charge.

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