Session: SE-01-01 Earthquake Resistance and Seismic Margin

Paper Number: 61963

Start Time: Tuesday, July 13, 2021, 09:00 AM

61963 - Seismic Test and Seismic Response Analysis of U-Shaped Tubes With Square Array in Steam Generator 

To ensure seismic integrity of steam generators during earthquakes. tube vibration stress has been evaluated by seismic response analysis using a simple model integrating multiple tubes. More latest realistic estimate than the conservative exsiting estimate is needed to cover increasing seismic load conditiones in Japanese reguration.
In this study, an analysis model has been developed by modeling each of tubes and anti-vibration bars (AVBs). Its calculated natural frequency and its mode were in good concordance with test results by using linear analysis model with connecting tubes and AVBs by linear springs. In addition, using the damping ratio obtained from the seismic tests, the displacement of the top of the tube bundle can be estimated by the response spectrum analysis.
Furthermore, a nonlinear analysis model using gap elements that simulate contact and sliding between the tubes and the AVBs has been developed to simulate stress distribution of the tubes.
First natural mode in this study is dominant during seismic excitation and is similar to the deflected shape of the tube bundle at a lateral inertia force. So, Static analysis is carried out by applying a lateral inertia force to the nonlinear analysis model to obtain top displacement of the tube bundle calculated by response spectrum analysis using the linear model. Stress distribution of the tubes calculated using the nonlinear analysis model were in good concordance with test results. The linear and nonlinear conbination analysis models in this study is applicable to the seisimic reguratoric caluculation for U-shaped square tube arrays in steam generator.

Presenting Author: Masatsugu Monde Mitsubishi Heavy Industries, Ltd.

Authors:

Kazuo Hirota Mitsubishi Heavy Industries, Ltd.
Masatsugu Monde Mitsubishi Heavy Industries, Ltd.
Naoki Ohno Mitsubishi Heavy Industries, Ltd.
Tomonori Mineno Mitsubishi Heavy Industries, Ltd.