How should I fasten pieces of wood to the joists to hang pullup bar?
Hello, I originally nailed in pipe hangers to the joists in order to hang a pull-up bar (see first picture below), but I inquired on here about its safety and was convinced that I need a better solution (not to mention that I put some small cracks in the joists when I did the nailing). As a result, I am now planning on using two pieces of 2x6 wood, with a hole cut in each, instead of the pipe hangers to support the pull-up bar (see second picture for an example of what I want to do). My question is, how should I fasten these two pieces of 2x6 wood to the joists? I have heard that bolts might be best. Since I have "double" joists in both spots where I will be fastening the 2x6s though (i.e. two joists side by side, which you can see in the first picture), and won't be able to use a nut on the other side of the joists to secure the bolt because the two joists together are too thick, I am wondering if bolts are the best solution or if I should just use screws instead. How should I fasten the pieces of 2x6 wood to the joists in a secure way that won't damage the joists?
Any input is greatly appreciated,