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Publication Number: FHWA-HRT-11-029
Date: February 2011
China Earthquake Reconnaissance Report: Performance of Transportation Structures During the May 12, 2008, M7.9 Wenchuan Earthquake
Figure 1. Photo. Members (from left to right) of the Wenchuan Earthquake Reconnaissance Team: Y. Hashash, G. Chen, P. Yen, C. Holub, M. Yashinsky, and K. Wang. This photo shows six members of the team that toured China following the Wenchuan earthquake. From left to right, the men shown are Dr. Youssef Hashash from Geo-Engineering Earthquake Reconnaissance, Dr. Genda Chen from the Center for Transportation Infrastructure and Safety, team leader Dr. Phillip W. Yen from the Turner-Fairbank Highway Research Center, Curtis Holub from the Mid-America Earthquake Center, Mark Yashinsky from the California Department of Transportation, and their host Dr. Kehai Wang of the Research Institute of Highway.
Figure 2. Map. Travel Path of Reconnaissance Team. This map shows the travel path the team took over 3 days to investigate the impact of the earthquake on transportation structures. The map shows three lines: The first line, depicting travel for July 21, 2008, includes a path extending northwest from Mianyang and a path extending west from Deyang and then southeast to Chengdu. The second line, depicting travel for July 22, 2008, begins at Nanba and extends south to Mianyang, Deyang, and Chengdu. The third line, depicting travel for July 23, 2008, begins at Chengdu and extends northwest to Dujiangyan and Yingxui. The third path travels closest to the earthquake epicenter, which is southwest of Yingxui.
Figure 3. Map. Bridge Sites Investigated by Reconnaissance Team. This map shows the same three travel paths depicted in figure 2, with flags to mark the structures investigated by the team. The flagged sites are bridges in Nanba Town, Anzhou Bridge, Baiyun Bridge, Nanhe Bridge, Mianyang Airport Viaduct, Tongji Bridge, Zhima Bridge, Jiajing Hotel, Baihua Bridge, Miaozhiping Bridge, and Shoujiang Bridge.
Figure 4. Photo. Historical Earthquake Activity. This map shows the epicenters of several earthquakes in the region surrounding the Longmen-Shan thrust zone. The epicenter of the 2008 Wenchuan earthquake is marked with a red star located northwest of Chengdu. Nine other earthquake epicenters are marked with purple circles and the earthquake magnitude and year. The latitude, longitude, and other details of the earthquakes are listed in table 1.
Figure 5. Photo. Surface Rupture of the Earthquake Fault. This series of three photos shows the path of surface rupture in the Longmen-Shan fault zone. The first photo shows the southwest end, the center photo shows a collapsed building, and the last photo shows the northeast end near the Ming River. A solid line crossing the photos diagonally indicates the path of surface rupture features: a sudden slope change of the mountain, buildings that were damaged next to buildings that collapsed, and dislocation across the river bed.
Figure 6. Photo. Surface Rupture Along the Old Highway Near the Collapsed Building. This photo shows the old Dujiangyan-Wenchuan highway in front of a collapsed building. There appears to be a significant upward slope in the road. Markings on the photo indicate that there is a vertical dislocation of approximately 4.92 ft (1.5 m).
Figure 7. Photo. Surface Rupture Near Xiaoyudong Bridge. This photo shows surface rupture in a field alongside Xiaoyudong Bridge, which suffered significant damage in the earthquake. The surface rupture appears as a slight hill perpendicular to the bridge. The vertical offset is more than 3.28 ft (1 m).
Figure 8. Photo. Surface Rupture Away From Xiaoyudong Bridge. This photo shows surface rupture in a field away from Xiaoyudong Bridge, which suffered significant damage in the earthquake. There are two men standing at the rupture location, with one on a slight rise of earth. Parallel lines at the top and bottom of the rise indicate the direction of the rupture and that the dislocation was less than 3.28 ft (1 m).
Figure 10. Photo. Welding on Bridge Railings. This photo shows military personnel welding steel railings on the Zhima Bridge. The men are dressed in camouflage uniforms. One is squatting, working on the lower portion of the railing while the other stands nearby.
Figure 11. Photo. Building Damage Near Zhima Bridge. This photo shows a village located near Zhima Bridge. Several damaged buildings with crumbling portions can be seen in the background. In the foreground are stacks of building material and a vehicle.
Figure 12. Photo. Tent Area Near the Bridge. This photo, taken from Zhima Bridge, shows rows of tents located near the village. The tents were most likely provided as shelters for people. The tops of at least 15 tents can be seen in the photo.
Figure 13. Photo. Overview of Tongji Bridge. This photo shows Tongji Bridge, a nine-span stone arch structure on reinforced concrete pier walls. The bridge spans a river in green, mountainous terrain and appears to lead into a populated area. The photo is marked with two circles. A small circle near the top of the bridge indicates leakage. A larger circle at the beginning of the bridge marks where the abutment was retrofitted to increase its strength prior to the earthquake.
Figure 14. Photo. Pounding Damage at Railing Joints. This pair of photos shows pounding damage at the railing joints of Tongji Bridge. The damage appears around a large crack between two large pieces of concrete. It appears angular chunks of the concrete have fallen off.
Figure 15. Illustration. Schematic Elevation View of Xiaoyudong Bridge. This diagram shows Xiaoyudong Bridge, a four-span arch structure supported on two abutments and three intermediate bents. Each span is 131.2 ft (40 m) long. The shaft foundations are 6.56 ft (2 m) in diameter.
Figure 16. Illustration. Typical Cross Section at Pier of Xiaoyudong Bridge. This diagram shows a single span of the bridge. There are four arches in each span. The diagram also shows the typical rigid frame as a substructure of the arch bridge.
Figure 17. Photo. Overall View of the Remaining Arches. This series of three photos shows the damage near bents 2, 3, and 4 of Xiaoyudong Bridge. Bent 2, located in the middle of the river is significantly tilted, and the bridge spans on either side are falling into the river. Bent 3 is also tilted, and the span to its left is entirely collapsed. Bent 4 shows the least damage, with the span to its left cracked and falling but not totally collapsed.
Figure 18. Photo. Significant Landslides Near the Bridge. This photo is a distant view of the side of a mountain that suffered serious landslides following the earthquake. The evidence of the landslides indicates severe shaking occurred around Xiaoyudung Bridge.
Figure 19. Photo. Damage in Easternmost Span. This photo shows significant damage to the easternmost span of Xiaoyudung Bridge. A displaced chunk of concrete at the top of the abutment on the far left of the bridge is marked shear key failure. Cracked, damaged concrete where the strut meets the span is marked shear failure. There is also an indication of shear failure at the bottom of the strut, near the ground. In addition, the arch is circled and marked arch against the levee.
Figure 20. Photo. Details of Shear Failures in Easternmost Span. This pair of photos shows close-up views of the shear failures in the easternmost span of Xiaoyudung Bridge. A large crack is in the strut near its connection to the span. Smaller cracking can be seen in the strut closer to the ground.
Figure 21. Illustration. Surface Fault Movement and Interaction with Bridge. This diagram shows a schematic of the interaction between the fault rupture and the east abutment of the bridge. When the hanging wall of the thrust fault moved up and right, the levee began to bear on the arches and added significant shear forces and bending moments, especially at the east ends of the arches. Designed for axial forces, the arches failed in shear at their east ends. The top end of the arches remained intact due mainly to its larger section.
Figure 22. Photo. Flexural Crack on Pile Shaft at Bent 4. This photo shows a crack in one of the pile shafts of Xiaoyudung Bridge. The crack is circled in white and extends horizontally across about half the width of the shaft.
Figure 23. Photo. Transverse Crack on Top of the Bridge Deck in Span 3. This photo shows cracks extending across the road on the deck of Xiaoyudung Bridge. There are two cracks in the photo. A smaller crack extends about midway across the road, and a large crack extends across the entire width of the bridge.
Figure 24. Illustration. Schematic of Anzhou Bridge. This diagram shows Anzhou Bridge, a two-arch structure with a slab superstructure. The diagram shows that each arch is 262.4 ft (80 m) in span. An inset diagram shows a detail of the deck and two arches with spalling and shear cracks marked.
Figure 25. Photo. Part of the Anzhou Bridge. This photo shows one of the two arches of Anzhou Bridge. The photo is taken from the ground, looking up at the bridge. One arch with cables extending to the superstructure can be seen. The bridge crosses a small body of water that appears relatively shallow.
Figure 27. Photo. Damage in Bridge Deck around Arch and Suspender. This set of three photos shows close-up views of damage to Anzhou Bridge. In all three photos, cracks are around the arches and joints of the bridge. The cracks appear to be relatively minor.
Figure 28. Photo. Road Block on Highway. This photo shows an official vehicle near a road block at the start of Anzhou Bridge. Traffic on the bridge was restricted to the middle of the deck due to minor damage on the bridge.
Figure 29. Photo. Temporary Roadway over the River. This photo shows a partially constructed roadway over the river next to Anzhou Bridge. An attempt was made to build the roadway with embankment materials and pipe culverts. The middle of the temporary bridge has been washed away by the water flowing in the river. Attempts to complete the bridge were abandoned.
Figure 30. Photo. Overview of Baimayan Bridge. This pair of photos shows Baimayan Bridge, a six-span skewed slab bridge supported on three-column bents. The bridge crosses a body of water in a hilly area with a significant amount of grass and trees.
Figure 32. Photo. Measurement of Expansion Joint Offset. This pair of photos shows an expansion joint on Baimayan Bridge. The joints were offset by approximately 2.73 inches (70 mm) in the traffic direction and 1.56 inches (40 mm) in the transverse direction. The joint crack is significant, and a ruler is being used to measure the displacement of the joints.
Figure 33. Photo. Building Damage in Nearby Town. This pair of photos shows severe damage to buildings in a town near Baimayan Bridge. Collapsed portions of buildings can be seen in addition to remaining rubble. The damage indicates that the level of shaking at the bridge site was significant.
Figure 35. Illustration. Schematic of Baiyun Bridge. This diagram shows the dimensions of Baiyun Bridge. The two side arches are 44.6 ft (13.6 m) high and 223 ft (68 m) wide. The center arch is 53.5 ft (16 m) high and 262.4 ft (80 m) wide. Tendons hold the arch in compression. There are two four-column bents in the center of the bridge and seat-type abutments on either side. The diagram marks where oil was leaking from tendon ducts on the left abutment.
Figure 36. Photo. Oil Leakage Underneath the Bridge Deck. This pair of photos show the underside of the Baiyun Bridge deck, where oil from the tendon ducks was leaking. An inset photo shows a close-up view of the oil leak.
Figure 37. Photo. Concrete Spalling and Cracks on Bridge Deck. This set of photos shows the damage on the Baiyun Bridge. Concrete spalling is around the arches, and cracking is apparent around the suspender.
Figure 40. Illustration. Schematic of the Mianyang Airport Viaduct. This diagram shows the schematic for the Mianyang Airport Viaduct. In the top portion of the diagram, an overhead view shows the viaduct as a U-shaped structure, opening to the left. There is a retaining wall on each approach section of the U. An indication of shear damage is marked on one side. A small detail view shows that reinforcing bars (smooth #2 at 6 inches and #9) are used in the concrete. The bottom portion of the diagram shows a side view of the sloped section of the viaduct.
Figure 41. Photo. Overview of the Viaduct Structure. This photo shows the side view of the sloped northwest approach in the foreground and the southeast approach in the background. The five bents of the background approach and an expansion joint are labeled. Inset is a close-up view of bent 5 of the northwest approach. Significant damage can be seen at the top of the column.
Figure 42. Photo. Shear Failure at West Column of Bent 5 of the Northwest Approach. This photo shows a close-up view of the damage to bent 5 of the northwest approach of the Mianyang Airport Viaduct. The outer concrete of the column is cracked and broken, and the metal reinforcement and aggregate fill material can be seen.
Figure 43. Photo. Shear Crack at East Column of Bent 5 of the Northwest Approach. This photo shows a close-up view of the damage to bent 5 of the northwest approach of the Mianyang Airport Viaduct. The column appears to have suffered less damage than the column in figure 42. Minor cracks can be seen in various locations on the column, but the aggregate and reinforcement is not exposed.
Figure 44. Photo. Crack on Retaining Wall Underneath the Northwest Approach. This photo shows damage to a retaining wall on the northwest approach of the Mianyang Airport Viaduct. The wall is intact, but there is a long, diagonal crack near the center of it.
Figure 45. Illustration. Three Bridges at Nanba Town. This diagram shows the bridges crossing a river near Nanba Town. An arrow pointing right indicates the direction of flow for the river. At the left side of the diagram is a crossed out bridge, representing a concrete and masonry three-span arch bridge built in the 1970s. This bridge collapsed completely during the earthquake. Downstream of the old bridge are 11 small rectangles representing a 10-span crossing that was under construction during the earthquake. Downstream of the two bridges is figure representing a temporary structure being constructed by launching Bailey bridges onto new reinforced concrete pier walls. To the left of the construction area is a temporary roadway with an embankment and pipe culverts.
Figure 46. Photo. Collapse of the Old Three-Arch Bridge. This pair of photos shows what is left of a completely collapsed three-arch bridge near Nanba Town. In the left photo, the remaining support structures can be seen. In the right photo, there are large chunks of concrete in a pile next to the abutment near the river's edge.
Figure 47. Photo. Damage Scenario of 10-Span Bridge Under Construction During the Earthquake. This photo shows the damage to the bridge that was under construction near Nanba Town. There are several two-column bents across the river. Some of the two-column bents are distorted. Several girders that had been placed appear to have moved or fallen in the earthquake. The concrete deck had not yet been poured at the time of the earthquake.
Figure 48. Photo. Damage to the 10-Span Bridge Under Construction. This photo shows a close-up view of the damage to the 10-span bridge that was under construction near Nanba Town at the time of the earthquake. Box girders can be seen crossing the river, but many are falling into the river or are out of place. Inset photos show damage to the end box girders and to the round, elastomeric pads that had supported each girder.
Figure 49. Photo. Overview of Temporary Bridge Construction. This photo shows a temporary bridge being constructed near the two damaged bridges near Nanba Town. The dirt road has been diverted around the site of the damaged, under-construction bridge, and vehicles are driving across the river on fill material laid over culverts.
Figure 51. Illustration. Plan and Elevation View of Miaozhiping Bridge. This figure shows the overall layout of Miaozhiping Bridge. The top section is an overhead view, with a dropped span marked near the center of the bridge. The bottom portion is an elevation view showing the tunnel that leads to the bridge, the dimensions of each span of the bridge, and the placement of the bridge's support columns.
Figure 52. Illustration. Cross Section of Main Span and Approach Bridge for Miaozhiping Bridge. This figure shows cross sections of box-girders in the main spans and T-girders in the approach spans. Section A-A is on the left and is 80.36 ft (24.5 m) wide with the top section 44.28 ft (13.5 m) high. Section B-B is on the right and is also 80.36 (24.5 m) wide.
Figure 53. Photo. Miaozhiping Tunnel. This pair of photos shows the Miaozhiping Tunnel. A larger photo shows a broad view of the tunnel entrance, which is located at the base of a mountain. There is an arched opening to the tunnel for each direction of traffic. A smaller, inset photo shows a close-up of the exit arch. Large trucks and machinery are being driven out of the tunnel.
Figure 54. Photo. Overview of Miaozhiping Bridge. This pair of photos shows Miaozhiping Bridge, which was under construction during the earthquake. A larger photo shows almost the entire bridge, which crosses a large body of water in a mountainous area. A dropped span near the middle of the bridge is clear in this photo. A smaller, inset photo shows a close-up of construction equipment and vehicles on the bridge.
Figure 55. Photo. Drop-Off Span and Construction Details Between Two Spans. This pair of photos shows part of Miaozhiping Bridge. The left photo shows a temporary pedestrian suspension walkway built over the lost span. The right photo shows the reinforcement and construction details with simply supported girders and continuous decks.
Figure 56. Photo. Longitudinal and Transverse Offset of Bridge Deck. This set of photos shows indications of severe movement in Miaozhiping Bridge during the earthquake. In the left photo, the longitudinal displacement is shown. Two barrier rails at the southeast expansion joint overlap by about 11.7 inches (300 mm). The right photo shows the transverse displacement with the barrier offset by about 9.75 inches (250 mm).
Figure 57. Photo. Shear Key Failure. This photo shows shear key failure in one section of Miaozhiping Bridge. The photo shows a middle length of the bridge, and a damaged portion can be seen where the supports meet the bridge deck.
Figure 58. Photo. End of Miaozhiping Bridge and its Overpass for the Old Highway. This pair of photos shows the end of the Miaozhiping Bridge on the left and the substructure of its overpass to support the old highway on the right. Near the tunnel, the Miaozhiping Bridge is divided into two parallel elevated structures to guide traffic in alignment with the tunnels.
Figure 59. Photo. Damage to Shear Key and Embankment of the Overpass. This pair of photos shows damage to the overpass of Miaozhiping Bridge. The left photo shows cracking concrete in the shear key where the support structure meets the bridge deck. The right photo shows cracking in the embankment on one side of the bridge.
Figure 60. Photo. Bridges in the Vicinity of Miaozhiping Bridge. This pair of photos shows two bridges in the vicinity of Miaozhiping Bridge. The bridges are reinforced-concrete girder bridges and suffered little damage in the earthquake.
Figure 61. Illustration. Schematic of Mingjiang Bridge at Yingxiu. This diagram shows two views of Mingjiang Bridge at Yingxiu. The main drawing shows two bridges, the Mingjiang and an undamaged suspension bridge, crossing the river. South of the bridges, the surface fault is marked. Near the fault, alongside the river, collapsed buildings, an offset tunnel, a collapsed levee, and a collapsed viaduct are marked. A smaller, inset diagram shows the side view of the bridge with four spans that are 88.56 ft (25 m) each.
Figure 62. Photo. Mingjiang Bridge and Other Structural Damage in Yingxiu Village. This photo shows the Mingjiang Bridge and the severe damage to structures around it. The bridge crosses a river in a mountainous area. On one side of the river, on the left of the photo, there are large piles of rubble and debris from the earthquake.
Figure 63. Illustration. Schematic of Baihua Bridge Before the Earthquake. This diagram shows the design of Baihua Bridge before it was damaged by the earthquake. The bridge is a curved structure, making an elongated S. The bridge is in six sections, with 19 two-column bents of varying heights. At the top curve, a section of three spans is circled and marked "Collapsed Spans."
Figure 64. Photo. Postearthquake Damage. This pair of photos shows the damage to Baihua Bridge after the earthquake. The main photo is an aerial shot of the bridge with one curved section entirely collapsed. A smaller, inset photo shows a view of the collapsed section from the ground. The broken support structure can be seen in a pile on the ground.
Figure 67. Photo. Column Shear and Flexural Failure at Bent 15. This photo shows severe damage near bent 15 of Baihua Bridge. The bridge section is completely collapsed probably due to the shear and flexural failure of the columns. A pile of concrete and metal can be seen in the photo.
Figure 68. Photo. Column Shear Failure and Section 5 Collapse at Bent 15. This pair of photos shows severe damage near bent 15 of Baihua Bridge. The roadway, broken and damaged, can be seen lying in a pile on the ground. In addition, one of the two-column bents, also badly damaged, can be seen on the ground.
Figure 69. Photo. Damage at Bent 18. This pair of photos highlights the damage at bent 18 of Baihua Bridge. The photos show the underside of the bridge. Spalling can be seen underneath the bridge deck in addition to cracks between the columns and the struts.
Figure 70. Photo. Blast Demolition of Baihua Bridge. This pair of photos shows the demolition of Baihua Bridge following the earthquake. The photos show dynamite causing the bridge to implode and creating large clouds of smoke and debris.
Figure 71. Photo. After Demolition of Baihua Bridge. This photo shows Baihua Bridge following demolition. The entire length of the bridge is lying on the ground, and the columns from the structure are strewn along the mountainside.
Figure 72. Illustration. Schematic of Zhima Bridge. This diagram shows Zhima Bridge, a four-span reinforced concrete T-girder structure. A temporary Bailey bridge built after the earthquake is also shown. The plan shows that each span is 65.6 ft (20 m).
Figure 73. Photo. Bailey Bridge over the Existing, Damaged Bridge. This photo shows the Bailey bridge that was built over Zhima Bridge after it was damaged in the earthquake. The bridge is a river crossing over a deep canyon in a mountainous area. Inset photos show shear key damage and damage to the end of the north span. The main photo shows that a temporary Bailey bridge was launched over the existing superstructure.
Figure 74. Illustration. Schematic of Shoujiang Bridge. This diagram shows Shoujiang Bridge. The bridge has eight spans, with four 98.4-ft (30-m) spans on each end and four 131.2-ft (40-m) spans in the center. The north side of the bridge is supported by two-column bents, while the center and the south side are supported by pier walls. The center support is 196.8 ft (60 m) high. A note at the north end of the bridge indicates that the span moved into the abutment and almost fell off the bent cap. A Bailey bridge was built over the last span on the north side.
Figure 75. Photo. Overview of the Bridge Structure and Damage Location. This pair of photos shows the damage to Shoujiang Bridge. The entire structure shifted north and then back, causing the first span to push onto the approach. In the left photo, damage and shear failure can be seen on the north end of the bridge. The deck appears cracked, and the bridge has shifted significantly. In the right photo, the length of the bridge can be seen. There is a Bailey bridge on the span at the north end and an extra support column built below the broken span. The south end of the bridge shows significantly less damage.