Dynamic Response Analysis of Mechanical Piping Systems Based on Response Spectrum Analysis: Comparison between the Pohang Earthquake Record and Design Response Spectra

This study investigates the dynamic response characteristics of a cooling water piping system (CWS) by comparing the response spectrum recorded during the 2017 Pohang earthquake with the design response spectrum outlined in the Korean Design Standard. Due to its large diameters and significant mass, the CWS is heavily influenced by inertial forces during seismic events, making it an effective benchmark for evaluating the applicability of design response spectra. Response spectrum analyses were performed using Bentley's AutoPIPE to evaluate pipe stress ratios, resultant displacements, and anchor forces under various load combinations. The findings reveal that the stress and displacement responses derived from the Pohang earthquake spectrum show spatial distributions and relative magnitudes similar to those obtained from the Korean Design Standard spectrum. Additionally, consistent response patterns were identified across different load combinations for both spectral inputs. Regarding anchor forces, thermal expansion loads dominated the response at certain locations. However, for specific load combinations, seismic loads generated anchor forces that were comparable to or even greater than those caused by thermal effects. These results suggest that, in the absence of site-specific earthquake records, the Korean Design Standard response spectrum serves as a reliable and practical foundation for assessing the seismic performance of CWS.