Construction Joint in Concrete Structures

Construction Joint in Concrete Structures There are cases where the pouring area is too large or for some other reason you need to cut the pouring. The cut or termination of pouring in concrete is called "construction joint". Don't be confused with a cold joint because they are not the same. Usually, it is a defect in concrete pouring. Technically it doesn’t just terminate the pouring just about anywhere. It has a specific location depending on the structure being poured. As per ACI 318M-14 section 26.5.6.2 and NSCP Section 426.5.6, I will show it side by side so you can see that they are just saying the same thing, because as I mentioned in my previous video “Structural Design Workflow”, the NSCP 2015 is based on ACI 318M-14 in concrete design. In the floor system, meaning the monolithic pouring of beams and slabs, the construction joint must be within the middle third of the span. And when it comes to the intersection of beams and girders, it is forbidden to place a construction joint within 2 beam widths away from the incident beam. What is the reason why it is ideal to place the construction joint in that location? This is because, if we go back to our structural analysis, here in this portion, there is less shear. For vertical members, such as columns and bearing walls, the cut should be at the top of the footing or floor. And on the underside of the beam to beam to column connection and on the underside of the slab in case of a flat slab supported by columns or bearing walls. You will not find this in ACI 318M-14 but instead in Chapter 3 of ACI 224.3R-95