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or receives environmental information from the supervisory controller gateway by internet, wireless or
PSTN. The supervisory controller gateway gathers post-earthquake bridge damage information on
which came from the supervisory controller unit through blue-tooth communication module, optical
fibers or cables, and sends them to the central control units. The systematic framework of the proposed
e-monitoring system for bridge post-earthquake evaluations and warnings is shown in Fig. 2.
Bridge Damage Lessons Learned From 921 Ji-Ji Earthquake
It is helpful to gather the historical bridges post-earthquake damage information for constructing a
remote earthquake supervisory control system for future highway bridges post-earthquake damage
evaluations and warnings. There are several bridges serious damages were reported after the Ji-Ji
earthquake that took place in Taiwan on Sep. 21, 1999. After conducting field investigations on about
990 bridges in Taichung, Changhua, Yunlin and Nantou counties since the 921 earthquake, the research
team found that nearly 200 bridges had sustained damage. "At least 25 bridges have been classified as
'extensively damaged' and nearly 70 percent of them were built prior to 1987, when older regulations
governing earthquake-resistant construction was in force. Bridges within 10km of the Chelungpu fault
were more vulnerable than elsewhere during 921 earthquake. Severe ground motion accompanied by a
sudden slip of the fault on Sept. 21 led to a number of different types of damage, including bridge
collapses, abutment tilt, pier breaks and crossbeam displacement. Scientists said that since it is hard for
engineers to avoid building bridges right over fault lines, which are scattered over across the country,
and that a better way to prevent disasters would be to build stronger bridges meeting stricter regulations.
Conclusions drawn from scientists and engineers suggest reclassifying the existing four earthquakeresistant
construction categories into two stricter categories.
In 2000, the construction regulations were revised, the highest earthquake-resistant coefficients would
be higher than the past threshold - which is 0.33G horizontal ground acceleration. Areas near the
Chelungpu fault certainly would be included in a new "Category 1," which would stand for the highest of
the two new proposed categories. Investigators found that different bridge designs resulted in different
kinds of damage, and therefore adopting innovative ways to build bridges should be considered in the
future. In the past, engineers tended to widen existing bridges without strengthening supporting piers
first, and me method resulted in disasters during 921 quake. The reason for the collapse of bridges built
by the Highway Bureau during the quake is because it adopted the simply supported beam system of
construction. This type of design is vulnerable during quakes. If engineers were to adopt a better system,
the continuous-beam system would be best for future bridge construction projects.