This is called a Swedish flame. Make your cuts like you're cutting cake, leave about 6 inches at the base, throw about a cap full of fuel oil in it. It burns up to two to three hours Can use olive oil instead of fuel oil :-) Any oil will burn!
Here are some design notes when it comes to modern pergola designs. The most common pergola design is to have decorative and somewhat rounded ends on the beam. The easiest way of creating a more modern pergola is to do away with the decorative ends.