It is a rare opportunity to monitor a damaged structure due to extensive cracking. The progress of cracks is of primary concern for maintenance. However, it is difficult to distinguish the extension due to structural degradation from temperature to traffic. A Structural Health Monitoring System (SHMS) was installed in a PC box-girder bridge in order to monitor the crack development. This SHMS has continuously worked for 7 years. The temperature and traffic load patterns were deduced from raw data by using correlation techniques. Although, crack opening displacement (COD) due to temperature of daily and yearly seasonal cycles is much larger than the COD due to trucks, the overall fatigue effect due to traffic is much larger than the temperature effect because of its sheer numbers, about 3000 per day. Overweight trucks are usually allowed with permit in major interstate highway. However, frequency change due to local fatigue of crack is negligible. This research can be helpful to explain why frequency is insensitive to local damage.

Date Published: 8 April 2009
PDF: 13 pages
Proc. SPIE 7294, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2009, 72940P (8 April 2009);

Published in SPIE Proceedings Vol. 7294:
Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2009
H. Felix Wu; Aaron A. Diaz; Peter J. Shull; Dietmar W. Vogel, Editor(s)