Repairing the Washington Monument
The good news: according to the National Park Service, computer models that simulated the Aug. 23, 2011 earthquake confirmed that damage to the Washington Monument is fixable, and the chance of another earthquake causing more damage is extremely unlikely. The bad news: damage was most severe near the top, where the monument was shaken most by the 5.8 magnitude quake, and a year later, the national icon remains closed for repairs that may take until 2014 to complete. See the extent of the damage, and how engineers believe it can be fixed.
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Total height:
555 feet
Stainless steel anchor bracket
Heaviest damage in top
Stone masonry on all four sides of the National Monument was damaged during last summer's earthquake, but the top section, known as the pyramidion, was most affected.
Repairing the top
Spalling or breakage of exterior panel corners, cracking of vertical “rib” supports and shifting of vertical joints must be addressed. Installation of stainless steel
anchor brackets would
connect exterior marble
panels to interior
marble blocks.
Damage to core
Masonry damage was prevalent along outer corners of the structure. Repairs will involve these four techniques:
Anchoring
Loose fragments are secured with adhesive and stainless steel anchors that are drilled in to the backing stone.
Patching
A rectangular shape is cut around missing stone and filled with one that matches the space and reinforced with stainless steel rods and mortar.
Sealing
Cracks are injected with epoxy-based adhesive until completely filled. Limestone dust is sprinkled on the surface to mask the crack.
Repointing
Damaged lime mortar is removed and replaced. The water-permeable material allows moisture to flow off of the structure instead of trapping it in the stones.
Shallow base
The base of the monument extends about 35 feet below ground level and sits on several layers of sand and clay.
Loam, fill and clay
Sand and clay
Sand, gravel and clay
Blue clay
SOURCE: National Park Service. GRAPHIC: Alberto Cuadra, Kathryn Faulkner, Cristina Rivero and Michael E. Ruane - The Washington Post. Published Aug. 23, 2012.
Repairing the National Cathedral
A team of engineers, masons and stone carvers soon will begin fixing damage from the August 2011 earthquake at the National Cathedral, a delicate process that is expected to cost at least $15 million and take a decade or more.
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