Patent GB-629355-A (GB)
Title: Improvements in or relating to the underpinning of buildings
IPC: E04G23/04
Filed: 1947-03-28
Abstract: 629,355. Underpinning buildings; foundations; building-blocks. PRYKE, F. March 28, 1947, No. 8465. Addition to 599,317. [Classes 20(ii) and 87(i)]  Damaged substructures or other loadbearing wall-like parts of buildings are removed and replaced by new work as in the parent Specification by just excavating a small portion of the damaged structure, building a supporting pier in the space, repeating this at intervals until the building is adequately underpinned, excavating the intervening damaged parts of the structure and finally forming in situ a beam-like reinforced concrete support in which the piers are embedded. The piers have channels lying in the direction of the wall above them and through which longitudinal reinforcing rods K pass, supported or located by rods B5, D5 passing through transverse holes in the blocks forming the piers. Additional longitudinal rods L, similarly supported pass outside the piers and transverse reinforcing members M, F and G are arranged around the longitudinal reinforcements both between and in the region of the piers. These transverse members resist shear stresses in the final concrete structure and if and where such stresses are expected to be large additional members N are provided having end portions parallel with the longitudinal reinforcements and intermediate portions approximately parallel to the direction of the diagonal tension resulting from the shear stresses. The members N may each be replaced by two members each having a straight end portion and an inclined main portion, the two main portions being parallel and secured together. Fig. 2 shows the assembly of a pier and associated transverse reinforcing members. The piers each comprise a flat base block A with slots A<SP>2</SP> A<SP>3</SP> to accommodate the transverse limbs of the U-shaped rods G. A channel block B is placed on the base block, having a rod B<SP>5</SP> through its side limbs to support the longitudinal rods passing through the channel. One or more intermediate flat blocks C with slots C<SP>2</SP>,C3 to accommodate a horizontal loop H is placed on the block B and another, inverted, channel block D on the block C. Finally a flat top block E, similar to the base block and having channels E<SP>4</SP>, E<SP>5</SP> to locate the horizontal limbs of the U-shaped rods F is placed on the block D. The rods F, G are located centrally of the pier by the loop H. The base block may have cut away corners A<SP>4</SP> to enable the rods G to lie horizontally while the block B is positioned. All the blocks have central vent holes A<SP>1</SP> B4 &c. to avoid the formation of air pockets when pouring the concrete. The channel blocks may be trapezoidal, as shown, so that the finished pier has a narrower central portion or waist to key the pier to the surrounding concrete. The blocks of a pier may be cemented together or merely rest on each other and may be of reinforced concrete or steel. The top and base blocks extend beyond the sides of the channel blocks and the top block has slots E<SP>2</SP>, E3 for venting purposes. Larger piers may be built from more blocks and piers placed side by side to take larger loads. To facilitate the placing of the rods F and G and the longitudinal rods L on the inside of a building the loop H may be replaced by two straight rods each passing through one of the slots C2, C3 and having a hook on its end which is engaged with the rods F, G on the inside face of the pier after the rest of the reinforcement has been positioned. The straight ends of the rods are then bent round the rods F, G at the outside face of the pier and secured together. The invention may be used to support the wall above when it is desired to cut a large doorway or other opening in a wall, or as an anchor for tie rods holding opposite walls of a building together.