We wanted a pre-fabricated pergola for our patio and found this one at Lowes.Problem: how to keep it stable and not blow over in heavy winds without permanently attaching it to the concrete.
Bought 4×4’s and metal base that holds 4×4’s. Then bought 4 cement squares. We bolted the 4×4’s into the metal base and screwed the metal base into the cement squares with special screws. The legs of the pergola are hollow and fit perfectly over the 4×4’s. Final step was leveling by using shims under the cement squares and then caulked the cement squares to the patio. Voilà – Great place to relax.