engleski

Influence of Rotational Stiffness between Column Elements on Global Stability of Historical Constructions

During the analysis of several historical constructions in Dubrovnik old town, we noticed difficulties of correct treatment to connections between elements of stone columns. These traditionally made contacts between columns elements are made with great care, so they can safely transmit only uniform compression stresses. Namely, carefully smoothed stone areas of contact joined with iron dowel centrically placed in a bit larger hole and finally filled with lead. Many damages and collapses related with described connections are reported to us by historical surveys. Indeed, we found many cracks and insets of different nuances and styles. All data indicates that these contacts have a permanent problem in time. Preliminary analysis showed insufficient dowel anchoring as fundamental deficiency. Therefore, dowel can safely transmit transverse force and small pulling force. Obviously this connection cannot transmit significant bending moments. Unfortunately, connections are usually eccentrically loaded by horizontal displacements and rotations of column elements. As a consequence fractures near the contacts are progressively stretching. Described problem was tested with various numerical models. We have made several detailed models of various complexity using SAP2000. Finally, 3D model with tetrahedral elements for cracks are programmed and inserted in FEAP 7.4. Numerical results and located fractures matched well, but many difficulties of accurate analysis and correct treatment of described connection are encountered. Amount of rotational stiffness is essential for understanding carrying mechanism of these structures and finding correct distribution of stresses and global stability of construction.

Historical constructions; Rotational stiffness; Columns connections; Dowel; Contact stress

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