Assessment of current design procedures for conical tanks under seismic loading

2013 ◽  
Vol 40 (12) ◽  
pp. 1151-1163 ◽  
Author(s):  
M. Jolie ◽  
M.M. Hassan ◽  
A.A. El Damatty
Keyword(s):  
Hydrodynamic Pressure ◽  
American Petroleum Institute ◽  
Eurocode 8 ◽  
Design Codes ◽  
Base Shear ◽  
Seismic Excitations ◽  
Equivalent Mechanical Model ◽  
Current Design ◽  
Conical Tanks ◽  
Cylindrical Tanks

This study is motivated by the fact that no design provisions currently exist specifically for conical tanks under seismic excitations. The design of liquid storage structures is governed by the American Water Works Association (AWWA), American Petroleum Institute (API), or Eurocode 8. An approximate method based on replacing the conical tank with an equivalent cylinder is given in these design codes. The state of stresses in conical tanks is different than that of cylindrical tanks. A previously established equivalent mechanical model is used to determine the response of a number of conical tanks under horizontal excitations. The models incorporate the different components of the hydrodynamic pressure and account for flexibility of the tank walls. Using an assortment of seismic hazard areas, the maximum base shear force and overturning moment are evaluated for a number of conical tanks. Those are compared to the corresponding values predicted by the design codes using the equivalent cylinder approach. The results reveal that this approximate approach is not adequate for designing conical tanks to resist seismic excitations.

A Comparative Study of Design Base Shear for RC Buildings in Selected Seismic Design Codes

2012 ◽  
Vol 28 (3) ◽  
pp. 1047-1070 ◽  
Author(s):  
Vijay Namdev Khose ◽  
Yogendra Singh ◽  
Dominik H. Lang
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Cumulative Effect ◽  
Building Design ◽  
Site Classification ◽  
Eurocode 8 ◽  
Design Codes ◽  
Base Shear ◽  
Rc Buildings ◽  
Design Response Spectrum

Modern seismic building design codes tend to converge on issues of design methodology and the state-of-the-art. However, significant differences exist in basic provisions of various codes. This paper compares important provisions related to the seismic design of RC buildings in some of the major national seismic building codes viz. ASCE 7, Eurocode 8, NZS 1170.5, and IS 1893. Code provisions regarding the specification of hazard, site classification, design response spectrum, ductility classification, response reduction factors, and minimum design base shear are compared and their cumulative effect on design base shear is studied. The objective component of overstrength contributed by the material and load factors is considered to normalize the design base shear. It is observed that every code has merit over the other codes in some aspect. The presented discussion highlights the major areas of differences which need attention in the process of harmonization of different codes of the world.

Seismic Response Analysis of Cylindrical Tanks With Initial Irregularities on Side Walls

1985 ◽  
Vol 107 (2) ◽  
pp. 107-117 ◽  
Author(s):  
H. Zui ◽  
T. Shinke
Keyword(s):  
Seismic Response ◽  
Hoop Stress ◽  
Hydrodynamic Pressure ◽  
Response Analysis ◽  
Vibrational Modes ◽  
Kinematic Equation ◽  
Current Design ◽  
Side Walls ◽  
Cylindrical Tanks ◽  
Natural Frequency Analysis

The objective of this paper is to report the findings of the study on the effects of initial irregularities on the seismic response of cylindrical tanks. The initial irregularities induce circumferential hydrodynamic pressure components of high-order modes, which are neglected in current design assumptions. Seismic response formulas for cylindrical tanks with arbitrary initial irregularities have been derived from Lagrange’s kinematic equation taking into account natural frequencies, vibrational modes and the hydrodynamic pressure. The hydrodynamic pressure in an irregular tank is evaluated by using velocity potential function. Natural frequency analysis is done by means of the transfer matrix method taking into consideration the initial hoop stress. The effect of aspect ratio H/D (H: liquid height and D: tank diameter) and the shape of initial irregularities are further examined by numerical calculations.

scholarly journals Simplified Plastic Hinge Model for Reinforced Concrete Beam–Column Joints with Eccentric Beams

2021 ◽  
Vol 11 (3) ◽  
pp. 1303
Author(s):  
Hyeon-Jong Hwang ◽  
Chang-Soo Kim
Keyword(s):  
Reinforced Concrete ◽  
Plastic Hinge ◽  
Eurocode 8 ◽  
Design Codes ◽  
Inelastic Behavior ◽  
Moment Frames ◽  
Loading Test ◽  
Current Design ◽  
Joint Width ◽  
Hinge Model

In nonlinear analysis for performance-based design of reinforced concrete moment frames, a plastic hinge spring element is predominantly used in order to simply and accurately describe the inelastic behavior of beam–column joints, including strength degradation. Although current design codes and guidelines provide various beam–column joint models, the focus is on concentric beam–column joints. Therefore, more studies are required for eccentric beam–column joints, which are also common in practice. In the present study, to consider the effect of beam eccentricity on the behavior of beam–column joints, a simplified plastic hinge model was proposed using the effective joint width of current design codes. The proposed model was compared to the cyclic loading test results of beam–column joints with/without beam eccentricity. The comparison showed that the simplified plastic hinge model with the effective joint width of NZS 3101-2006 or Eurocode 8 is considered acceptable for design purpose.

Sloshing Effects on the Seismic Design of Horizontal-Cylindrical and Spherical Industrial Vessels

2005 ◽  
Vol 128 (3) ◽  
pp. 328-340 ◽  
Author(s):  
Spyros A. Karamanos ◽  
Lazaros A. Patkas ◽  
Manolis A. Platyrrachos
Keyword(s):  
Seismic Design ◽  
Fluid Motion ◽  
Eurocode 8 ◽  
Free Surface Elevation ◽  
Spherical Vessel ◽  
Seismic Force ◽  
Earthquake Design ◽  
Current Design ◽  
Mechanical Models ◽  
Cylindrical Tanks

The present paper investigates sloshing effects on the earthquake design of horizontal-cylindrical and spherical industrial vessels. Assuming small-amplitude free-surface elevation, a linearized sloshing problem is obtained, and its solution provides sloshing frequencies, modes, and masses. Based on an “impulsive-convective” decomposition of the container-fluid motion, an efficient methodology is proposed for the calculation of seismic force. The methodology gives rise to appropriate spring-mass mechanical models, which represent sloshing effects on the container-fluid system in an elegant and simple manner. Special issues, such as the deformability of horizontal-cylindrical containers or the flexibility of spherical vessel supports, are also taken into account. The proposed methodology can be used to calculate the seismic force, in the framework of liquid container earthquake design, and extends the current design practice for vertical cylindrical tanks stated in existing seismic design specifications (e.g., API Standard 650 and Eurocode 8). The methodology is illustrated in three design examples.

Seismic response of concrete rectangular tanks for liquid containing structures

2005 ◽  
Vol 32 (4) ◽  
pp. 739-752 ◽  
Author(s):  
J Z Chen ◽  
M R Kianoush
Keyword(s):  
Time History ◽  
Hydrodynamic Pressure ◽  
Rigid Wall ◽  
Tank Wall ◽  
Base Shear ◽  
Lumped Mass ◽  
Sequential Method ◽  
Wall Flexibility ◽  
Current Design ◽  
Impulsive Response

In this paper, a procedure for computing hydrodynamic pressures in rectangular tanks is proposed. The procedure, which is referred to as the sequential method, considers the effect of the flexibility of the tank wall in determining the hydrodynamic pressures. In this study, only the impulsive response of the tank is considered. Based on a two-dimensional model of the tank wall, dynamic time-history analysis is carried out to study the effect of wall flexibility on the response. In the analysis, both a tall tank and a shallow tank are considered. The results of analysis are compared with those obtained based on current design practice codes and standards. The well-known Housner's model, which assumes that the mass of liquid is lumped on the wall based on rigid wall boundary condition in the calculation of hydrodynamic pressure, is widely used in practice. A comparison shows that in most cases, the lumped mass approach overestimates the base shear. The effect of wall flexibility on wall displacements, base shears, and moments are also discussed.Key words: reinforced concrete, liquid containing, rectangular tank, seismic, dynamic analysis, tank flexibility.

A Single Technically Consistent Design Formula for the Thickness of Cylindrical Sections Under Internal Pressure

2006 ◽  
Vol 129 (1) ◽  
pp. 211-215 ◽  
Author(s):  
John D. Fishburn
Keyword(s):  
Experimental Data ◽  
Internal Pressure ◽  
State Of The Art ◽  
Original Data ◽  
Pressure Vessels ◽  
Time Dependent ◽  
Design Codes ◽  
Recent Developments ◽  
Current Design ◽  
Single Formula

Within the current design codes for boilers, piping, and pressure vessels, there are many different equations for the thickness of a cylindrical section under internal pressure. A reassessment of these various formulations, using the original data, is described together with more recent developments in the state of the art. A single formula, which can be demonstrated to retain the same design margin in both the time-dependent and time-independent regimes, is shown to give the best correlation with the experimental data and is proposed for consideration for inclusion in the design codes.

scholarly journals ASSESSMENT OF THE SEISMIC RESISTANCE DEFICIT OF BRICK MASONRY CHIMNEY ACCORDING TO RELEVANT DESIGN CODES

2020 ◽  
pp. 13-25
Author(s):  
Z. K. Abaev ◽  
M. Yu. Kodzaev ◽  
A. D. Valiev
Keyword(s):  
Brick Masonry ◽  
Building Codes ◽  
Earthquake Resistance ◽  
Seismic Resistance ◽  
Design Codes ◽  
Sustainable Operation ◽  
Current Design ◽  
The City

Most of the brick masonry chimneys located in earthquake-prone areas were built long before the current design codes were adopted, which poses a great threat to the sustainable operation and development of the city industry as a whole. This article presents a consistent example of assessing the deficit of earthquake resistance of a brick masonry chimney and gives general conclusions about changes in main coefficients of designed codes. This study aims to quantify the deficit of earthquake resistance of brick masonry chimney according to the relevant Building Codes “SP 14.13330.2018 Construction in seismic areas”.

scholarly journals Shear and Flexural Stiffnesses of Reinforced Concrete Shear Walls Subjected to Cyclic Loading

2014 ◽  
Vol 8 (1) ◽  
pp. 104-121 ◽  
Author(s):  
T. O. Tang ◽  
R. K.L. Su
Keyword(s):  
Seismic Analysis ◽  
Classical Mechanics ◽  
Shear Walls ◽  
Shear Stiffness ◽  
Eurocode 8 ◽  
Design Codes ◽  
Structural Walls ◽  
Load Distributions ◽  
Classical Models ◽  
Ductility Capacity

Seismic analyses of concrete structures under maximum-considered earthquakes require the use of reduced stiffness accounting for cracks and degraded materials. Structural walls, different to other flexural dominated components, are sensitive to both shear and flexural stiffness degradations. Adoption of the gross shear stiffness for walls in seismic analysis prevails particularly for the design codes in the US. Yet available experimental results indicate that this could overstate the shear stiffness by more than double, which would hamper the actual predictions of building periods and shear load distributions among columns and walls. In addition, the deformation capacity could be drastically understated if the stipulated constant ductility capacity is adopted. This paper reviews the available simplified shear and flexural models, which stem from classical mechanics, empirical formulations and/or parametric studies, suitable for structural walls at the state-of-the-art. Reviews on the recommended flexural and shear stiffnesses by prominent design codes such as ACI318-11, Eurocode 8 and CSA are included. A database comprised of walls subjected to reverse-cyclic loads is formed to evaluate the performance of each model. It is found that there exist classical models that could outweigh overconservative codified values with comparable simplicity for practical uses.

UK Programme on Codes, Standards and Procedure Needs for SMR and Gen IV Reactors: Phase 1 Output

2019 ◽  
Author(s):  
P. M. James ◽  
N. J. Underwood ◽  
J. K. Sharples
Keyword(s):  
Phase 1 ◽  
Nuclear Research ◽  
Growth Strategy ◽  
Design Codes ◽  
Low Carbon ◽  
Current Design ◽  
Uk Government ◽  
Gen Iv ◽  
The Uk ◽  
Low Carbon Energy

Abstract The UK government has committed to a clean growth strategy, whereby it is legally bound to reduce the UK’s greenhouse gas emissions by at least 80% by 2050 compared to levels in 1990. In order to achieve this the UK needs to develop low carbon energy sources for electricity, transportation, domestic and industrial heat, light and power. This, combined with the fact that the UK demand for electricity is likely to double by 2050, poses a significant challenge for the UK. In light of these finding the UK government has invested £250 million into nuclear research and development (R&D), thus recognising the key role that nuclear plays in producing low carbon, clean, safe and reliable energy for the UK both now and into the future. This paper provides an overview of the ongoing activities in the UK within this R&D programme focused on developing a UK forward plan for defining the long term requirements for the design codes and standards for small modular reactors (SMRs) and generation (Gen) IV reactors (also including advanced modular reactors). The project is being undertaken by Wood Nuclear and National Nuclear Laboratory (NNL). In order to ensure a complete UK perspective is captured, an advisory board has been established with experts in this field, from academia, industry and also national laboratories. Discussions with all parties produced a series of items to be addressed in order for current Design Codes and Standards to be applicable for SMR and Gen IV reactors. This paper summarises these activities and key findings.

Fatigue Assessment of Drill Pipes

2017 ◽  
Author(s):  
P. J. Haagensen ◽  
T. I. Grøttum
Keyword(s):  
Failure Modes ◽  
Fatigue Behavior ◽  
Drill String ◽  
American Petroleum Institute ◽  
Directional Drilling ◽  
Fatigue Wear ◽  
Threaded Connections ◽  
Current Design ◽  
Drilling Operations ◽  
Drill Pipes

Fatigue failures during offshore drilling operations is still a very costly problem. The fatigue behavior of drill pipes is reviewed, and typical failure modes are identified. The effects of drill string curvature during directional drilling on pipe body stress and on the fatigue life is examined. Effects on applied mean stress from drill string weight are discussed. Interaction effects of degradation mechanisms such as fatigue, wear and corrosion are evaluated. Experimental background data and statistical evaluation that form the basis for the current design practice issued by American Petroleum Institute (API) and other guidance in codes and standards is reviewed. Results from several recent testing programs performed under rotating bending of pipes with threaded connections, and tests involving the pipe body under resonance conditions are presented. The tests were made with pipe sizes from 2 7/8 in. to 5 7/8 in. in Grade S-135 pipes. The results are compared with published test data and design guidance such as API Recommended Practice G7 [1]. Recommendations are given for research and testing to improve reliability and the safe operation of drill strings.

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