Earthquake Load Reduction Effects of Boiler Structures by High Energy Absorbing Seismic Ties

Abstract

Seismic ties are steel energy absorbing devices installed between the boiler and its support structure. This paper deals with the relationship between the energy absorption of a new type of seismic tie (made of low yield strength steel and with an optimized I-sectional shape) and its reduction effect on the resultant shear force of the support structure. To quantify the relationship between the energy absorption and the reduction effect on the resultant shear force, time-history analyses using a lumped mass vibration model that simulates the boiler structure, were performed for three representative design seismic waves (The largest class (level 2) waves of Taft, El Centro and Hachinohe earthquakes). The time-history analysis results demonstrated that the energy absorption increasing rates of the new seismic ties were correlated quantitatively with the shear force reduction rates of the support structure for the three design seismic waves.