Preserving History:
The Structural Analysis of Fort Sumter - II
Mrinal
1MS
1
Dutta ,
Dr.
2
Sez Atamturktur ,
Rick
3
Dorrance
Student, Clemson University; 2Associate Professor, Clemson University; 3Chief of Resource Management, NPS.
Fort Sumter is a pentagonal fortification located approximately 3000ft from the main
navigational channel into the port of Charleston. It is of interest to focus on structural analysis
of this historic masonry structure.
Interacting irregular geometrical forms such as arches, piers, walls and vaults of the fort and
material constitutive properties which have also changed over time give rise to complex and
uncertain interaction difficult to model in finite element software.
A comparative nonlinear response study of a simple arch model under controlled impact
excitation to evaluate performance in terms of load-displacement measurements along with
incremental development of cracks against established literature. This is to mark a trade-off
between conflicting objectives of fidelity and robustness. The developed element material
models are then suitably applied to the FE model of Fort Sumter.
Fig 1. Fort Sumter: Finite Element Model
Fig 2. Fort Sumter: Salient Angle & Right Face
Material Model Development:
Proposed Experimental Data:
I.
II.
Ramos’ Arch Model Development and Static Experiment:
•
Laboratory tests carried out in the Structural Laboratory of the
Civil Engineering Department of the University of Minho (Fig
5).
•
Selected sensors for the static test are five LVDTs and a load
cell.
•
Progressive and controlled damage applied by statically
increasing load to damage state. Fig 6 shows the crack
formation sequence.
Fig 3. Fort Sumter: Left Flank
Fig 4. Fort Sumter: Left Face
Brown and Pretlove’s Dynamic Experiment:
•
Monotonic loading of arches at Nottingham University (Fig 7).
Fig 6. Crack Formation Sequence
Fig 8. Change in frequency of the dominant mode of vibration
under increasing load.
Brown and Pretlove’s Dynamic Experiment (Contd.):
•
Formation of cracks causes local reduction of
stiffness and hence natural frequency (Fig 8).
•
Vibration based techniques can be used to improve
serviceability assessment of masonry arch
structures.
Fig 5. Ramos’ arch test: Measuring point location (left) ; Test
apparatus (right)
Fig 7. Nottingham Arch of Pretlove’s experiments
Images Reference: [1] Ramos L.F. Damage identification on masonry structures based on vibration signatures. PhD Thesis, University of Minho; 2007 [2] Brown G., Pretlove A.J., Ellick J.C.A., Hogg V., Choo B.S. Changes in the Dynamic
Characteristics of a masonry arch bridge subjected to monotonic loading to failure. Arch bridges, London;1995.