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Nondestructive Testing Probes Dome’s Safety Presented By: Rania Gamal EL-Din Ahmed By: Charles Linn,FAIA Web Address:

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Presentation on theme: "Nondestructive Testing Probes Dome’s Safety Presented By: Rania Gamal EL-Din Ahmed By: Charles Linn,FAIA Web Address:"— Presentation transcript:

1 Nondestructive Testing Probes Dome’s Safety Presented By: Rania Gamal EL-Din Ahmed By: Charles Linn,FAIA Web Address: Topic Number: 75 Date: March,2003

2 Introduction. The importance of the library. The construction of the library. Laser surveys. Nondestructive testing techniques. Measuring Measuring movement.Conclusion. Contents:-

3 Introduction:- The location of the library The importance of the library:- It’s the administrative center of the University and houses the offices of the President and the Provost.The rotunda, originally the Library’s main reading room, is now used for exhibitions and major University events. It’s the administrative center of the University and houses the offices of the President and the Provost.The rotunda, originally the Library’s main reading room, is now used for exhibitions and major University events.

4 The construction of the library:- A photograph of Low Memorial Library taken after its completion gives an indication of the dome's overall size. The inner dome:- is made of plaster on iron frame supported metal lath. The outer dome:- whose drum is supported by monumental arches and pendentives, is sheathed with limestone panels. ItIt is Greek-cross shaped in plan, with a central rotunda covered by a pair of domes.

5 Huge brick arches built on top of the stone which is supporting the outer dome. The monumental stone arches visible inside the rotunda do a small job of supporting Low’s mansory outer dome. In the upper attic the outer dome can be seen arching over the iron & lath that support the inner dome.

6 Laser survey simplifies CAD drawings and structural analysis:- Silman Associates used version 7.44 of SAP2000 Plus, a program for static and dynamic finite element analysis of structures. The GB Geotechnics quickly established dimensions by positioning a laser surveying instrument in a number of locations in and around the building. Millions of measurements taken using a laser surveying instrument were transformed into AutoCAD models and construction drawings.

7 Among the graphical options for SAP2000 Plus The wire-frame axonometrics that use different colors to represent different kinds of stress. The wire-frame axonometrics that use different colors to represent different kinds of stress. This diagram represents a rendering of the dome’s structure. These diagrams use color to indicate the level of stress distribution. Red and orange tones are tensile stresses. Other colors indicate compression.

8 Nondestructive testing techniques:- There was a variety of nondestructive testing methods and that allowed the team to "see" the dome's structure without penetrating it. And there are two types:- There was a variety of nondestructive testing methods and that allowed the team to "see" the dome's structure without penetrating it. And there are two types:- Impulse radar:- It uses an instrument to measure the speed at which high frequency electromagnetic waves applied to a surface bounce back.It’s convenient to use in locations that are difficult to reach. Electromagnetic detection:- It uses an instrument that passes an alternating electrical current through a coil of metallic wire that creates a magnetic field. When the coil is passed over a surface and the instrument indicates disturbance,it means the presence of a ferrous material. By these 2 ways they found that the dome is made of unreinforced brick.

9 Measuring movement :- To determine how much Low's dome is moving, oc had Vibra-Tech, a Mount Holly, N.J.–based consulting firm, install a remote vibration monitoring system. Eighteen devices, called vibrating wire crack meters. To determine how much Low's dome is moving, Silman Associates had Vibra-Tech, a Mount Holly, N.J.–based consulting firm, install a remote vibration monitoring system. Eighteen devices, called vibrating wire crack meters. The crack meter is attached by a cable to the data logger. used high-wire to support himself in midair to determine that the plaster was attached and to conduct a video survey of areas.Diebolt used high-wire to support himself in midair to determine that the plaster was attached and to conduct a video survey of areas. The graph shows how much movement has been measured by crack meters installed on all four arches.

10 Conclusion:- and have concluded that Low's dome is QUIET SAFE. Helpern Architects and Robert Silman Associates have concluded that Low's dome is QUIET SAFE. So there was an important question….. Has the testing therefore been a colossal waste of money? So there was an important question….. Has the testing therefore been a colossal waste of money? No, because considering that the building is irreplaceable, and safety is a concern. It is a bonus that it has probably been studied more thoroughly than any unreinforced masonry dome. Irwin Lefkowitz adds, "Low has served Columbia University well for more than 100 years. We want to ensure that it will serve us for 100 more." No, because considering that the building is irreplaceable, and safety is a concern. It is a bonus that it has probably been studied more thoroughly than any unreinforced masonry dome. Irwin Lefkowitz adds, "Low has served Columbia University well for more than 100 years. We want to ensure that it will serve us for 100 more."

11 Thanks for your attention…


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