St. Johns College
Temporary Propping
Temporary Works & Enabling Works,
Structural Assessments & Surveys,
Heritage Access
St. John’s is one of 32 colleges at the University of Oxford and is a grade I listed building dating back to the 16th – 17th century. The east and west facades of the Canterbury quadrangle have ornately decorated features supported by a series of stone columns. During construction, the stone columns were installed such that the layers of the sedimentary rock run vertically rather than horizontally, causing fissures to appear. RDG were commissioned to design a temporary propping scheme to facilitate the removal and replacement of the columns. An initial site inspection revealed that the capital stone was not a monolithic piece and therefore could not be relied upon to transfer load.
The frontispiece consists of double columns on either side of a central arch supporting an ornate façade above. Refurbishment of the permanent works foundations was also required. To ensure congestion around the foundations were kept to a minimum, the temporary works foundations were designed using inclined props positioned at 3 locations around the column. The stonework was supported by a T-shaped header beam arrangement.
The frontispiece consists of double columns on either side of a central arch supporting an ornate façade above. Refurbishment of the permanent works foundations was also required. To ensure congestion around the foundations were kept to a minimum, the temporary works foundations were designed using inclined props positioned at 3 locations around the column. The stonework was supported by a T-shaped header beam arrangement.
The remaining arches positioned along the rest of the façade were supported using a compressive layer of shaped plywood fronted Filcor, designed to distribute load onto a propped scaffold system. Existing services running close to the surface of the courtyard ground restricted the size and location of the temporary works foundations. Raking members were required to transfer the load from the wide arch support frame to the narrow concrete foundation.
Steel lifting frames were also designed to lift, manoeuvre, and position the existing and replacement stone column pieces. All the temporary works were to be designed such that the deflections were limited to 2mm as a precautionary measure in case of settlements occurring during scheduled works.
The remaining arches positioned along the rest of the façade were supported using a compressive layer of shaped plywood fronted Filcor, designed to distribute load onto a propped scaffold system. Existing services running close to the surface of the courtyard ground restricted the size and location of the temporary works foundations. Raking members were required to transfer the load from the wide arch support frame to the narrow concrete foundation.
Steel lifting frames were also designed to lift, manoeuvre, and position the existing and replacement stone column pieces. All the temporary works were to be designed such that the deflections were limited to 2mm as a precautionary measure in case of settlements occurring during scheduled works.
