A 10 m-high locally supported silo containing flour or sugar is analyzed. The horizontal cross-section of the 6.2 m-high vertical walls is an irregular octagon with four sides of 1.9 m and the remaining four of 0.7 m. The walls and upper hopper (from the top section of the columns to the bottom boundary of the walls) are made of stainless steel of class AISI 430 and have a thickness of 1.5 mm. The lower hopper (below the the top section of the columns) is made of stainless steel of class AISI 304 and has a thickness of 3 mm. The silo was installed into a site with PGA approximately equal to agS = 0.3g for TR = 475 years. Elasto-plastic analyses in the presence of geometric nonlinearities and initial imperfection were carried out. The L-shaped columns showed torsional buckling under serviceability conditions. Therefore, they were replaced with box section profiles. Moreover, the stiffening of the ring positioned at the transition between upper and lower parts of the hopper was proposed. The seismic response is ruled by the mass of the contained solid. Then, a pushover analysis with a mass-proportional lateral force profile was conducted. The capacity curve is almost linear up to failure of the rings in the upper part of the walls. At this load level, the shell elements in the hopper have largely exceeded the elastic range. However, due to the proposed retrofitting, the seismic resistance is adequate.
Valutazione della sicurezza e progetto di rinforzo di un silo in acciaio per polveri in zona sismica/Assessment and retrofitting of a metal silo for granular solids to be installed in seismic zone
MINGHINI, Fabio;TULLINI, Nerio
2017
Abstract
A 10 m-high locally supported silo containing flour or sugar is analyzed. The horizontal cross-section of the 6.2 m-high vertical walls is an irregular octagon with four sides of 1.9 m and the remaining four of 0.7 m. The walls and upper hopper (from the top section of the columns to the bottom boundary of the walls) are made of stainless steel of class AISI 430 and have a thickness of 1.5 mm. The lower hopper (below the the top section of the columns) is made of stainless steel of class AISI 304 and has a thickness of 3 mm. The silo was installed into a site with PGA approximately equal to agS = 0.3g for TR = 475 years. Elasto-plastic analyses in the presence of geometric nonlinearities and initial imperfection were carried out. The L-shaped columns showed torsional buckling under serviceability conditions. Therefore, they were replaced with box section profiles. Moreover, the stiffening of the ring positioned at the transition between upper and lower parts of the hopper was proposed. The seismic response is ruled by the mass of the contained solid. Then, a pushover analysis with a mass-proportional lateral force profile was conducted. The capacity curve is almost linear up to failure of the rings in the upper part of the walls. At this load level, the shell elements in the hopper have largely exceeded the elastic range. However, due to the proposed retrofitting, the seismic resistance is adequate.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
