Errichtung eines in historischer Bauweise von unten gemauerten Zellengewölbes mit minimaler Unterstützung der Grate

Construction of a cell vault by a historical method with minimal support of the ridges.

Cell vaults are a specific type of the late-Gothic vaulting without bearing ribs. The construction period is the 15th and 16th century. After that, the knowledge for the construction of cell vaults had been lost. In particular, it is unclear, how they could been built with very little wood in accordance with historical records. The crucial question is therefore, how the load is carried during the different phases of construction.
On the geometry of existing cell vaults can be seen, that apparently there has been support and shape control only for the ridges, while the other brick masonry was built without support or formwork.
The wood used for support can be kept low by the masonry contributing a large part to the load transfer already during the construction phase. This is achieved in the beginning by the steep ridges which do not need support, then through the mutual supporting and stiffening of the cell parts and in the shallower parts, versus the middle of the vault, by the emergence of an annular pressure force. This ring compression force arising here is similar to the construction of a dome.
As a part of a diploma thesis in a temporarily vacant space at the HTWK Leipzig a cell vault was built by historical methods in spring 2010. The cross-section of the supporting wooden arches below the ridges could be kept low at 3.6 cm × 7.0 cm at a distance of the columns of 70 cm, so that always there exists a passage from one cell to the other to enable the mason to move under the cell vault for building it from below. The cross-section of the columns was 5.8 cm × 5.8 cm. The actual load at the wooden arches and columns was monitored continuously during the construction phase. According to the results, the cross-section of the wood even could have been reduced by 20—30 %.
The experience in the construction of the cell vault shows, that the dead load of the vault must be transferred only partly by a timber construction, while the bigger part of the load is transferred by the masonry itself by different mechanisms depending on the construction phase.