The pro­fes­sio­nal ancho­ring of a tim­ber frame con­s­truc­tion requi­res the car­pen­ter to have sta­tic know­ledge of forces in wall panes, edge spa­cing of fas­ten­ers and know­ledge of sin­gle-cut wood joints. In addi­ti­on, he should know what addi­tio­nal forces can ari­se from an off-cen­tral con­nec­tion. When assembling an alre­a­dy clo­sed wall and in the absence of a straigh­tening thres­hold, as is cus­to­ma­ry in pre­fa­bri­ca­ted con­s­truc­tion, he must the­r­e­fo­re pay atten­ti­on to careful ten­si­on and thrust anchoring.

Load case 1 : Load in wall level

In the case of a hori­zon­tal wind load on the gab­le with trans­mis­si­on via the cei­ling disc into the traught frames, lar­ge ver­ti­cal com­pres­si­ve and ten­si­le forces often ari­se at the edges of nar­row eaves or inner wall panes. In par­ti­cu­lar, ten­si­le forces that occur in com­bi­na­ti­on with thrust in the lon­gi­tu­di­nal direc­tion of the wall must be secu­re­ly ancho­red. The­se loads occur recipro­cal­ly. This means that a ten­si­le and thrust ancho­ra­ge must be sta­ti­cal­ly detec­ted at the two edges of the wall disc. Howe­ver, it is not pos­si­ble to deri­ve the shear forces via fric­tion due to the exis­ting moun­ting wed­ges under the thres­hold. An under-mortar with swel­ling mortar can also not sol­ve the shear problem.

Load case 2 : Load transverse to the wall plane

The wind loads from pres­su­re and suc­tion trans­ver­se­ly to the wall level (wind on eaves) must also be dis­si­pa­ted via ancho­ra­ges. For the exact deter­mi­na­ti­on of the ten­si­le ancho­ring forces, which also take into account the dead weight of the con­s­truc­tion, various struc­tu­ral pro­grams are available on the mar­ket, e.B” “Dia­mo-Wind”. The choice of a sui­ta­ble train ancho­ra­ge should always be made by the car­pen­ter tog­e­ther with the respon­si­ble struc­tu­ral engi­neer, and not only for lia­bi­li­ty reasons. The solu­ti­on of sim­ply remo­ving the ten­si­le and thrust forces in the thres­hold area with a rib ang­le and long nails can only be war­ned. This case is sta­ti­cal­ly unde­tec­ta­ble and the­r­e­fo­re ques­tionable. The fol­lo­wing pro­blem is the basis : When car­pen­ters place a pul­ley in the OSB pla­te joint and attach it with nails through the pla­te to the woo­den stem behind it, the requi­red edge distances to the OSB pla­te joint must be main­tai­ned. On the other hand, the force-locked clam­ping of the OSB pla­te with the stem in the sup­p­ly glass area must be detec­ted. From a sta­tic point of view, the stem takes over the func­tion of the edge car­ri­er of a thrust field. The exis­ting ten­si­le or, depen­ding on the load attack, also com­pres­si­ve force is the­r­e­fo­re always in the stem and must be intro­du­ced into the feed glass via the OSB inter­me­dia­te layer.

Single and double cuts

From a sta­tic point of view, this con­nec­tion is not two-cut, but twice sin­gle-cut. Only if the pla­te was glued to the stem would this con­nec­tion cle­ar­ly fail to be sin­gle-cut. Many manu­fac­tu­r­ers recom­mend a force-fit nai­ling of the OSB pla­te with the stem abo­ve the pull glass in order to initia­te the ten­si­le force into the OSB pla­te before­hand. Howe­ver, this would mean that the OSB pla­te would have to be detec­ted exact­ly abo­ve the end of the feed glass for the full upward trac­tion force. It beco­mes pro­ble­ma­tic if the inter­me­dia­te lay­er does not con­sist of OSB boards, but of gyp­sum fib­re boards (e.B. Fer­macell). The pre­vious­ly known ten­si­le anchors reach their sta­tic limits when initia­ting addi­tio­nal thrust forces from load case 1, which always occur in com­bi­na­ti­on with the ten­si­le force. That is, they tear or burst out.

Force decomposition solves problems

A solu­ti­on to this pro­blem pro­mi­ses a new­ly deve­lo­ped train con­nec­tion (ÜH mark accor­ding to DIN 1052). The so-cal­led “Tri‑Z anchor” intro­du­ces the forces from ten­si­on and thrust into the ancho­ring sys­tem via an incli­ned screw con­nec­tion wit­hout stres­sing the inter­me­dia­te lay­er (OSB or gyp­sum fib­re­board) on she­ars. Edge distances of fas­ten­ers in the pla­te area are no lon­ger decisi­ve. The incli­ned screw con­nec­tion leads to a force decom­po­si­ti­on, through which the screw only has to trans­mit ten­si­le forces and the inter­me­dia­te lay­er only com­pres­si­ve forces. Instal­la­ti­on is simp­le : the lan­yard is sim­ply pla­ced on the plan­king in the flo­or area and atta­ched to the hand­le and thres­hold with incli­ned screws. The con­nec­tion is able to safe­ly initia­te thrust forces from load cases 1 and 2 via the incli­ned screws into the tie rod and final­ly into the base pla­te via a dowel. The known con­nec­tion extre­mes and moun­ting tole­ran­ces of up to 3 cm to the base pla­te are taken into account. The con­nec­tor is available in the Tri‑Z and Tri-Z-Mini ver­si­ons with low power transmission.