EMA Strengthening Solutions

EMA Poles are common telecom structures in city centres. EMA poles are usually held by standoffs attached to a plate and connected to a wall through anchor bolts. The forces generated causes the anchors to want to pull out from the wall. Historically, these anchors are held by chemical resins injected into the wall. Click here for description of chemical resin anchors. Usually, where the pull out load is excessive, the resin anchors become unsuitable to resist pull out and strengthening solutions needs to be adopted where the EMA is existing. There are two possible strengthening solutions

Back plating: This involves using a bolt that passes through the wall to the other end held by a back plate. In this case, pull out of the bolt is resisted by the rigid connection of the plates and nuts at the back. For the bolts to pull-out, the entire wall will have to cave in. Hence, the proposal of a back-end plate negates the need to pull test the anchors.

Over plating: This involves increasing the number of bolts and spacing of the existing anchors. A small Equal angle (EA) steel section is placed over the existing front plate and new bolt holes are drilled at the top and bottom of the EA for new bolts to pass through the wall. This increases the number of bolts and hence reduces the pull-out force as the forces are shared by 6No. bolts as opposed to 4Nos as shown in the fig 2b below.