Seismic Design Challenges of High Pressure Riser Systems on Gravity Based Structures

2019 ◽  
Author(s):  
Mahesh Sonawane ◽  
Rohit Vaidya ◽  
Ronak Kadakia ◽  
Hunter Haeberle ◽  
Phil Ward
Keyword(s):  
High Pressure ◽  
Case Studies ◽  
Seismic Analysis ◽  
Interaction Model ◽  
Time History ◽  
Seismic Loading ◽  
System Response ◽  
Seismic Load ◽  
Adjacent Structures ◽  
Ground Motion Records

Abstract This paper presents two case studies of the seismic analysis of high pressure riser and conductor systems used on shallow water fixed platforms (approximately 120m water depth) offshore Newfoundland and Labrador, Canada. The case studies presented consider the Hebron and White Rose extension Husky gravity-based concrete platforms. A methodology is presented to assess the dynamic and resonant response of each conductor and riser system to seismic loading using a fully integrated conductor and platform interaction model. Seismic loading is an application of an earthquake-generated agitation to a structure. This occurs at contact surfaces either with the ground, or with adjacent structures, or with gravity waves. Nonlinear time history analyses of the riser system subjected to various ground motion records are performed to simulate the seismic load. Design considerations that drive the HP riser design are discussed. The paper addresses the intricacies of the gravity base concrete platform-riser system interaction, initial configuration and dynamic seismic response. The riser and conductor system response is used to determine HP riser connector and centralization requirements. The learnings taken from the detailed modeling method are presented along with the advantages of this methodology.

scholarly journals Approach for Selection of Rayleigh Damping Parameters Used for Time History Analysis

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
R. E. Spears ◽  
S. R. Jensen
Keyword(s):  
Seismic Analysis ◽  
Time History ◽  
System Response ◽  
Piping System ◽  
Nuclear Facilities ◽  
Rayleigh Damping ◽  
Modal Damping ◽  
American Society ◽  
Selection Of ◽  
Civil Engineers

Nonlinearities, whether geometric or material, need to be addressed in seismic analysis. One good analysis method that can address these nonlinearities is direct time integration with Rayleigh damping. Modal damping is the damping typically specified in seismic analysis Codes and Standards (ASCE 4-98, 1998, “Seismic Analysis of Safety-Related Nuclear Structures and Commentary,” American Society of Civil Engineers, Reston, Virginia and ASCE/SEI 43-05, 2005, “Seismic Design Criteria for Structures, Systems, and Components in Nuclear Facilities,” American Society of Civil Engineers, Reston, Virginia.). Modal damping is constant for all frequencies where Rayleigh damping varies with frequency. An approach is proposed here for selection of Rayleigh damping coefficients to be used in seismic analyses that is consistent with given modal damping. The approach uses the difference between the modal damping response and the Rayleigh damping response along with effective mass properties of the model being evaluated to match overall system response levels. This paper provides a simple example problem to demonstrate the approach. It also provides results for a finite element model representing an existing piping system. Displacement, acceleration, and stress results are compared from model runs using modal damping and model runs using Rayleigh damping with coefficients selected using the proposed method.

Seismic Analysis of Large Buried Culvert Structures

1996 ◽  
Vol 1541 (1) ◽  
pp. 133-139 ◽  
Author(s):  
Peter M. Byrne ◽  
D. L. Anderson ◽  
Hendra Jitno
Keyword(s):  
Seismic Analysis ◽  
Seismic Loading ◽  
Unit Weight ◽  
Seismic Load ◽  
Vertical Acceleration ◽  
Finite Element Analyses ◽  
Ground Movements ◽  
Dynamic Finite Element ◽  
Soil Structures ◽  
Surrounding Soil

Field experience indicates that large buried culverts have suffered essentially no damage during past earthquakes when no significant permanent ground movements have occurred. These soil structures, which generally comprise steel or concrete arch members and engineered soil, may have spans of 15 m. Static, pseudodynamic, and dynamic finite-element analyses have been carried out on these structures and indicate that for horizontal seismic loading, the surrounding soil is much stiffer than the arch and results in the seismic load being taken by the soil rather than by the arch. Under vertical seismic loading, the arch is stiffer than the surrounding soil and attracts significant load, which can essentially be accounted for by increasing the unit weight of the soil in proportion to the vertical acceleration. Thrusts and moments in a 10-m concrete arch are examined under combined static and seismic loading (both horizontal and vertical). The results indicate that significant increases in thrust and moment in the arch are predicted for peak ground accelerations in excess of 0.3 g. The good behavior of these structures under such acceleration levels in California, where they are not specifically designed for earthquake forces, indicates that their static design includes sufficient reserve to prevent failure under accelerations of these levels.

A Parametric Study of Independent Support Motion Method for the Steam Supply Piping Connected to the HP Turbine of APR 1400

2013 ◽  
Author(s):  
Dae Soo Kim ◽  
Joon Ho Lee ◽  
In Yeung Kim
Keyword(s):  
High Pressure ◽  
Power Plant ◽  
Support Groups ◽  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Nuclear Industry ◽  
Combination Method ◽  
Piping System ◽  
Support Motion

The steam supply piping connected to the high pressure (HP) turbine of APR1400 (Korea’s advanced power plant 1400 MW-class) is a typical example of multi-supported piping system, and it is routed from the Containment building to the Turbine building via the Main Steam Isolation Valve House in the Auxiliary building. In the seismic analysis of this piping system, using the Enveloped Response Spectrum (ERS) method, a commonly used methodology for seismic analysis of nuclear power plant piping in industry circles, generates overly conservative analysis results. Therefore, Time History Method (THM) which applies excitation characteristic of each support attached to individual building was used to eliminate unnecessary conservatism. However, it was noticed that the Time History Method requires considerable amount of labor and time in generating combined time history equivalent to the spectrum applied for each support although it is regarded as the most exact and realistic method for seismic analysis. The nuclear industry has been making lots of efforts in finding out the mathematic logicality and practical applicability to resolve this issue. This paper deals with parametric research on combination effects of responses between support groups, damping effects, and modal combination method with close modes in applying the Independent Support Motion (ISM) method to the analysis model of the steam supply piping connected to the high pressure turbine of APR1400. Quantitative assessment and comparison with the analysis results of the ERS method and THM were also carried out. As a result, it is shown that the analysis results of the ISM method together with the SRSS combination between support groups, 4% damping with ±15% spectrum peak broadening and grouping of modal combination are remarkably similar to those of THM.

scholarly journals Approach for Selection of Rayleigh Damping Parameters Used for Time History Analysis

2009 ◽  
Author(s):  
R. E. Spears ◽  
S. R. Jensen
Keyword(s):  
Seismic Analysis ◽  
Time Integration ◽  
Time History ◽  
Element Model ◽  
System Response ◽  
Piping System ◽  
Rayleigh Damping ◽  
Modal Damping ◽  
The Difference ◽  
Selection Of

Nonlinearities, whether geometric or material, need to be addressed in seismic analysis. One good analysis method that can address these nonlinearities is direct time integration with Rayleigh damping. Modal damping is the damping typically specified in seismic analysis Codes and Standards [1, 2]. Modal damping is constant for all frequencies where Rayleigh damping varies with frequency. An approach is proposed here for selection of Rayleigh damping coefficients to be used in seismic analyses that are consistent with given Modal damping. The approach uses the difference between the modal damping response and the Rayleigh damping response along with effective mass properties of the model being evaluated to match overall system response levels. This paper provides a simple example problem to demonstrate the approach. It also provides results for a finite element model representing an existing piping system. Displacement, acceleration, and stress results are compared from model runs using modal damping and model runs using Rayleigh damping with coefficients selected using the proposed method.

Analysis of Anti-Seismic Fortified Length of Tunnel Portal in High Seismic Intensity Area

2011 ◽  
Vol 90-93 ◽  
pp. 2057-2061 ◽  
Author(s):  
Lin Jie Chen ◽  
Bo Liang
Keyword(s):  
Interaction Model ◽  
Time History ◽  
Axial Direction ◽  
Seismic Intensity ◽  
Weak Links ◽  
Seismic Load ◽  
Highway Tunnel ◽  
Seismic Motion ◽  
History Analysis ◽  
Tunnel Portal

In high seismic intensity area, strong seismic motion may cause the ruin of highway tunnel, especially the tunnel portal which is the weak links for anti-seismic fortifying. Based on soil-structure interaction model, 3D seismic responses of tunnel portal, in combination with the Menglian tunnel engineering on the Bao-Teng Highway in Yunnan, were performed by using viscous-spring artificial boundary and time history analysis method. The anti-seismic fortified length of tunnel portal to the effects of dynamic and crack property was studied. The results show that the acceleration of lining gradually decreases with the lining extends to the tunnel body under the high-intensity seismic load. Along the axial direction of the tunnel, the crack from the portal 50m is not obvious. The results provide references for the tunnel anti-seismic design．

Seismic Response Analysis of an Adsorption Tower Based on ANSYS

2010 ◽  
Vol 102-104 ◽  
pp. 150-154
Author(s):  
Xiao Ping Hu ◽  
Xiao Ping Ye
Keyword(s):  
Seismic Response ◽  
Seismic Analysis ◽  
Time History ◽  
Element Model ◽  
Response Analysis ◽  
Seismic Load ◽  
Engineering Practice ◽  
Current Standard ◽  
History Analysis ◽  
Tower Equipment

The seismic load usually has a significant hazard to the safety of the tower equipment, so it’s important to execute of seismic design in engineering practice. In this paper, the time history analysis of the seismic response is carried out with the help of ANSYS software for the finite element model of the adsorption tower. Relevant time history data is obtained. Compared with seismic analysis of the current standard method, corresponding suggestions are given.

Seismic Analysis of Lead-Bismuth-Cooled Fast Reactor Vessel

2013 ◽  
Author(s):  
Juan Ma ◽  
Mei Huang
Keyword(s):  
Fast Reactor ◽  
Structural Integrity ◽  
Seismic Analysis ◽  
Time History ◽  
Hydrodynamic Pressure ◽  
Seismic Loading ◽  
Reactor Vessel ◽  
Analysis Model ◽  
Element Analysis ◽  
Set Up

This paper is aimed at analyzing the structural responses of a Generation IV heavy-liquid-metal-cooled reactor (lead-bismuth-cooled fast reactor) vessel in the event of earthquake. For a seismic design, the seismic time history response analyses are carried out for both a top support type and a bottom support type. It is found that the bottom support type exhibits the better performance. There is the gap between the reactor vessel and guard vessel being filled with [1] argon. It is indispensable to add bellows at vessel upper end for a bottom support type to achieve the connection and seal between the reactor vessel and guard vessel. This paper is the first attempt to evaluate the effects on structural seismic performance by adopting the equivalent springs to simulate this elastic connection. For a seismic investigation, there is a key issue that should be focused on, namely: the fluid-structure interaction due to seismic loading. The vessel is filled with a high-density fluid and might lead to severe hydrodynamic pressure significantly in the occurrence of earthquake. It will impair the structural integrity of reactor vessel. In order to study the structure effects of reactor vessel under seismic loading, an appropriate 3-D finite element analysis model has to be set up and the FEM code ANSYS has been implemented.

scholarly journals COMPARISON OF METHODS USED FOR SEISMIC ANALYSIS OF STRUCTURES

2017 ◽  
Vol 13 ◽  
pp. 20 ◽  
Author(s):  
Petr Čada ◽  
Jiří Máca
Keyword(s):  
Seismic Analysis ◽  
Linear Time ◽  
Dynamic Properties ◽  
Response Spectrum ◽  
Time History ◽  
Time History Analysis ◽  
Seismic Load ◽  
Eurocode 8 ◽  
History Analysis ◽  
Non Linear

This paper investigates effects of the seismic load to a structure. The article describes main methods of the definition and practical application of the seismic load based on the Standard Eurocode 8. There was made a comparison of all methods using the same structure. A simple two-storeyed concrete 2D-frame with fixed joints was chosen. A one another model with rigid beams for some calculations was defined. The second model can be used for hand-calculations as a cantilever with two masses. The paper describes main dynamic properties of the chosen structure. Seismic load was defined by lateral force method, modal response spectrum, non-linear time-history analysis and pushover analysis. The time-history analysis is represented by accelerograms. There were made linear and non-linear calculations.

Study on Shock Absorption Measures of Highway Tunnel in Karst Areas

2011 ◽  
Vol 90-93 ◽  
pp. 2178-2182
Author(s):  
Lin Jie Chen ◽  
Bo Liang
Keyword(s):  
Soil Structure ◽  
Interaction Model ◽  
Time History ◽  
Surrounding Rock ◽  
Seismic Load ◽  
Analysis Method ◽  
Shock Absorption ◽  
Highway Tunnel ◽  
History Analysis ◽  
Karst Areas

Based on soil-structure interaction model, the response analyses of the Menglian tunnel by using viscous-spring artificial boundary and time history analysis method under earthquake accelerations and multiform conditions of surrounding rocks are presented. The seismic responses of the tunnel are calculated by changing parameters of surrounding rocks within certain influencing distances to the linings. The shock absorption effects, applicability, and shock mechanisms of grouting in the surrounding rock are analyzed. The results show that the displacements and stresses of the tunnel linings in karst areas decrease by grouting in the surrounding rock, under the high-intensity seismic load, and the linings are protected when the grouting measure is used. It also shows that the shock absorption effect is better with the increase of the grouting density and range. By calculating analysis, it can achieve the shock absorption effects when the grouting range is 5.5 to 7.0m in the Menglian tunnel. The results provide useful reference for the shock absorption design of tunnel.

scholarly journals Dynamic seismic analysis of bridge using response spectrum and time history method

2021 ◽  
Author(s):  
Marame Brinissat ◽  
Rajmund Kuti ◽  
Zouhir Louhibi
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Bending Moment ◽  
Highway Bridge ◽  
Structural Elements ◽  
Base Shear ◽  
Shear Forces ◽  
Nonlinear Analyses ◽  
Ground Motion Records

Dynamic analysis is very important to better understand the performance of structural elements of a bridge. For this purpose, a seismic analysis of an Algerian highway bridge designed with the new Algerian seismic bridge regulation (RPOA -2008) was carried out using linear and nonlinear analyses. Therefore, response spectrum, time history analyses were performed to evaluate the seismic responses of the designed bridge. The performance of the designed bridge is assessed using 10 ground motion records. The proposed methodology allows an efficient comparison of the seismic response of the bridge in terms of base shear forces, bending moment and displacements. Finally, the paper concludes with a discussion of the specific outcomes.

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