A key component of the research has been testing at very large scale
in the Winter Laboratory. Large-scale experiments sponsored by NSF
through MCEER and the U.S.-Japan Urban Earthquake Disaster Mitigation
Program in conjunction with Tokyo Gas, Ltd. were successfully completed
to evaluate the effects of earthquake-induced ground rupture on welded
steel pipelines with elbows. The experimental set-up involved the
largest full-scale replication of ground deformation effects on pipelines
ever performed in the laboratory. Figure 1 shows two experimental
basins with a total of 60-65 metric tons of soil that were displaced
1 m relative to each other to simulate the type of abrupt displacement
generated by liquefaction-induced lateral spread, landslides, and
surface faulting.
The tests allowed for calibration of a sophisticated soil-pipeline
interaction analytical program developed in conjunction with the
experimental work, known as the Hybrid Model. This model combines
three dimensional shell elements to evaluate the complex deformation
and strain state induced by severe ground movement at steel elbows
with two-dimensional beam elements to simulate soil-pipeline interaction
along relatively large distances of pipeline connected to the elbow
(Yoshizaki, et al., 2001).
The experimental data and analytical modeling products are of direct
relevance for underground gas, water, petroleum, and electrical
conduits. They provide evidence critical for developing the next
generation of analytical models for three-dimensional assessment
of pipe stress and deformation. The resulting analytical models
permit greater reliability and sophistication in the evaluation
of pipeline response to ground failure. The results are increased
public safety through improved engineering and more cost-effective
deployment and sitting strategies for utility companies.
The research has also involved laboratory tests on full-scale pipeline
specimens that were fabricated in the field by Los Angeles Department
of Water and Power (LADWP) and shipped to the Cornell Winter Laboratory.
This research has been performed through MCEER in conjunction with
LADWP and contractors specializing in the fabrication and installation
of fiber reinforced polymer composites (FRCs).
Figure 1. Overhead view of test basin before and after the experiment
(NOTE: Basin is over 10m long, max. 5m wide and 1.2m deep)
This work is supported primarily by the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Program of the National Science Foundation under Award Number CMS-0217366.
