Seismic performance of the Pennguard chimney lining system
Wilson J.L. & de Kreij A.
CICIND REPORT Vol. 18, No. 2, 2002
Order No: CR-227
The 2001 edition of the CICIND model code for concrete chimneys encourages the designer to include the effects of ductility when designing chimneys in high seismic regions. The inclusion of ductility results in lower seismic forces, significant cost savings and safer chimneys, and could result in significant cracking and local longitudinal tensile strains in the order of 1-3% in the windshield under extreme earthquake excitation (return period in excess of 500 years).
In regions of medium to high seismicity, top-hung steel liner systems are usually cost effective as they possess good strength to weight ratios and being a tension system have some inherent ductility. As an alternative solution, the installation of the lightweight borosilicate blocks (Pennguard ® Block Lining System) attached directly to the inside face of the windshield appears to have considerable merit from a cost and performance perspective. The 50mm thick borosilicate glass blocks possess excellent thermal and acid resisting properties. In addition the blocks are extremely light (with a specific weight in the order of 0.2) and therefore transmit a negligible seismic force to the windshield and hence are ideal in high seismic regions
The results from the test program reported in this paper demonstrate that the overall performance of the Pennguard blocks and adhesive was excellent and superior to that of the reinforced concrete windshield when subject to earthquake ground shaking. The adhesive membrane used to attach the blocks to the windshield has some flexibility thus allowing some relative movement between the two surfaces. During moderate earthquake events that induce less than 1% longitudinal strain in the windshield, the Pennguard blocks and adhesive would be undamaged, although the cracks in the windshield would need some minor repairs. Under extreme earthquake events that could significantly damage the windshield and induce longitudinal strains in the order of 1-3%, the Pennguard ® Block Lining System would be damaged but would remain intact and be repairable.