Washington+Monument+Evaluation+&+Restoration

Washington Monument Evaluation & Restoration //Hannah Noss BAE/MAE Penn State 2015 // toc
 * Mineral, Virginia - August 23, 2011 **

Introduction
On August 23, 2011, much of the eastern coast of the United States felt the effects of an earthquake. The event caused damage to many buildings and structures located in the Mineral, Virginia (about 90 miles southwest of Washington, D.C.) area as well as many others, including notable structures such as the Washington Monument. The event caused the National Park Service (NPS) to close the Monument until repairs were made. Much of the damage occurred at the pyramidion at the top of the structure. Since the monument is made of marble and stone, most of the damage consisted of cracking and spalling of the materials and mortar joints. Many panels and verticals were cracked and chipped. Wiss, Janey, Elstner Associates, Inc. (WJE) was hired by the National Park Service to assess the damages. To analyze the monument and perform a seismic assessment, an experienced team rappelled and examined the entire exterior of the monument. Since the event, the monument has been repaired and reopened to the public on May 12, 2014.

The design and construction of the monument took place over several years. The idea of the monument to honor George Washington came about in the 1780s. In 1836, the Washington National Monument Society held a design competition in which Robert Morris won. Over the course of construction, monetary issues and the Civil War put the project on hold. It sat unfinished for 25 years until Thomas Casey and the U.S. Army Corp of Engineers completed the project. In February of 1885, the monument was dedicated. (Hansen 2008).

Today, the monument stands just over 555 feet. It consists of stone from three different quarries which can be seen in the different coloring on the monument. During the initial construction of the monument, the stone came from a quarry in Baltimore, however, when construction started again 25 years later, the original quarry was no longer in business. A quarry in Massachusetts was then used, but the stone it produced was not consistent in color or quality, so another quarry in Baltimore provided the stone for the rest of the project. The pyramidion at the top consists of 300 tons of marble supported by angled buttresses. (National Park Service 2015)

Events Leading Up to the Damage (Earthquake)
The earthquake struck Mineral, Virginia around 1:51PM EDT. In the Central Virginia Seismic Zone, the United States Geological Survey measured the magnitude of the earthquake as a 5.8Mw occurring about 3.7 miles below grade.(WJE no date) The movement/shaking of the ground caused the monument to respond with a swaying motion. Initially, many NPS employees (not inside the monument) thought the noise and movement was caused by a low flying helicopter, however, as the movement increased, they realized the situation was much more serious. Since so many visitors and park ra ngers were in the Washington Monument at the time of the Earthquake, everyone's safety was the top concern. Fortunately, everyone was okay. After the event, park rangers immediately noticed a large amount of debris on the plaza surrounding the monument as well as in the monument as shown in the image below. The rangers also saw large cracks at the top portion of the structure. (NPS, Earthquake)



Investigation
Immediately after the earthquake, park rangers noticed cracks at the to p of the monument and debris on the plaza below. NPS worked quickly in order to evaluate the condition of the monument and have it fixed as soon as possible. Tipping Mar served as the lead engineering team with NPS engineers to examine the earthquake and monument's reaction and damage. The National Park Service teamed with WJE to perform a comprehensive investigation of the monument.

WJE's Difficult Access Team (DAT) which is trained to inspect hard-to-reach locations was employed to rappel the exterior of the monument. All precautions were taken to ensure the safety of the workers during the process. Communication plans, weather plans, and proper rappelling training helped better prepare the engineering team for the assessment. The team was all SPRAT certified (Society of Professional Rope Access Technicians). (Gambino 2011)

Three days after the earthquake hit the area, Hurricane Irene was in the forecast to hit the Washington, D.C. area. The team worked around the clock to prepare emergency repairs for the monument before the storm hit. (NPS 2015). Even after the hurricane, weather was tracked daily to secure the safety of those rappelling the monument. Aside from severe weather concerns, the investigative team was required to work with other challenges. With the monument's proximity to the White House, it was important that the team be aware of the events taking place. The rappellers and scaffolding also attracted the attention of the media throughout the examination.

While scaling the side of the structure, engineers used tablets to record the damaged they found on the drawings and compared it to the damage that was found during pre-earthquake investigations of the monument in 1999 and 2000. They took photos and material samples to test. (Buckley, 2014). After the on site inspection, the engineering team analyzed the results and prepared recommendations for NPS.

Damage
According to engineers, the monument behaved as expected during the earthquake. During an earth quake, a building typically sways back and forth, responding to the motion of the earth. Since the monument is a long shaft, the base remained in place as it is close to the ground and more rigid than the top. The top of the monument, the pyramidion, saw the most movement, therefore, it experienced the most damage.

The damage the monument experienced included (WJE 2012): > Below Pyramidion
 * Pyramidion
 * Cracks in marble panels
 * Spalling at corner of marble panels
 * Cracks at rib bearing locations
 * Vertical cracks in tie beams
 * Displaced lightning protection system
 * Water leaks
 * Vertical mortar joints missing between 450ft to 500ft level
 * Water leaks
 * Elevator counter weight (steel rods) bent
 * Previous cracks (that were repaired) failed again

Since the base of the monument did not move, it did not experience much damage. Most of the debris that NPS workers found on the plaza was that from damage above. The image below shows a large crack in a marble panel on the monument's pyramidion.

Evaluation and Repair
To properly evaluate the building after preforming the on-site assessment, WJE analyzed the monument in Perform 3D by Computers and Structures, Inc. The team created a 3D model of the structure and evaluated it for for a Maximum Considered Earthquake and for the Mineral, Virginia earthquake it actually experienced. The engineers worked to properly model the materials and material properties of the monument in order to achieve the most accurate results. The top portion of the monument behaves non-linearly where as the lower portion has nonlinear potential. The model proved that the movement of the structure in the event of an earthquake is small in comparison to the height of the structure. (WJE 2012)

Following the investigation of the monument and scaling of the structure, the team assessed the damag e and put together a repair plan. To address the cracked marble, WJE recommended that a stainless steel plate be anchored into the panel on either side of the crack in order to prevent the panel from further deformation and sealant be placed in the crack to block water infiltration into the monument. Marble that was spalled was fixed by anchoring the spalled marble (if it was in good condition) or new marble, provided by a quarry in Baltimore to best match the existing marble, to the location in which it fell out. In order to repair the cracks at rib bearing locations where the bearing area was reduced, a stainless steel plate were added to serve as the connection for the marble panel and rib. The missing vertical mortar joints were cleaned had a new sealant added. To addressed the displaced lightning protection system, WJE recommended that the system be removed, repaired, and reinstalled. (WJE 2012)

Perini Management Services worked to perform the repairs for the monument. (Buckley 2014)



Similar Cases
Many buildings other than the Washington Monument suffered loss due to the Earthquake. In the Washington, D.C. area, the Washington National Cathedral, Smithsonian Castle, and National Museum of Natural History incurred various damage as a result of the earth's movement.

The National Cathedral in Washington, D.C. was subject to damage due to the Mineral, Virginia Earthquake without major structural concerns. The earthquake created approximately $32 million in damage on both the exterior and interior of the cathedral. The first phase, which was completed by James G. Davis Construction on February 18, 2015, finished $10 million of the repair work. During phase 1, cracks were fixed in the buttresses on the cathedral's exterior and cracks and spalls on the interior. To perform such repairs without disrupting the events and services within the cathedral, the construction crew had to set up scaffolding 65 feet in the air. Phase 2 will begin when the monetary funds necessary are raided by the cathedral. (Cardno 2015)

Conclusion
NPS and the engineering firms learned a lot from the Mineral, Virginia earthquake. Since the east coast of the United States does not typically experience earthquakes, this was an opportunity to understand how the older buildings and monuments would react to such an event. The NPS learned more about the structural integrity of the Washington Monument as well as many other older structures. The full depth analysis taught engineers more about the behavior of structures in events and how to alter designs in the future for such events.

After the earthquake, NPS, WJE and Tipping Mar worked hard to investigate the damage and fix the problems while maintaining a safe working environment at extreme heights.The team was able to preserve an important and historic American icon. The monument performed well during the seismic event, suffering only minor damage, even though it was not designed for such conditions. WJE and Tipping Mar performed in depth analyses to study the monument and recommended the best repair options. On May 12, 2014, almost three years after the earthquake, the monument reopened to the public.

Additional Resources and References
This action plan addresses the actions taken up to October 3 regarding WJE’s report, Press Conferences, weather conditions, etc.
 * Bagent, Bethany. (2011) ‘Incident Action Plan 2011 Earthquake Assessment’. NPS Incident Briefing. October 3, 2011.**

This source documents the response of the monument to the ground movement. The authors explain the soils beneath the monument, the damage the monument experienced, and the geology of the area surrounding the monument. The majority of the report discusses the soils and seismic activity in the Mineral, Virginia area.
 * Egan, John; Murphy, Debra; Wells, Donald. (2014). ‘Ground shaking and structural response of the Washington Monument during the 2011 Mineral, Virginia, earthquake’. //Geological Society of America Special Papers// 2015, 509, 199-233.**