The frogs need a hole in the ice that might accumulate over the winter for oxygen to get into the water. If there is no hole in the ice, the frogs will die from asphyxiation. I use a trough warmer. My pond is about 150 gallons. Many others have a variety of methods, so you might want to search the site for other methods.

I know that I keep a hole in the ice with a heater. They need a place to burrow into and hibernate.

I haven't had any frogs at my pond yet, but one thing I've read on past threads that can work well is a bunch (or couple bunches) of quilt batting in the bottom of the pond. Don't know if you'd just layer it or wad it up, but apparently the frogs liked it just fine.

I lose frogs every year. In the spring I'll find them under my rock edging or dead and white at the bottom of the pond. I love frogs probably more then the fish them selves but can't figure out how to keep them. I'm sure some of them survived because I had 2 or 3 that hung out all summer.

Frogs will do what frogs will do!
You can place a basin of sand for them to lay in, on the bottom of your pond.
You can weight down a layer or two of quilt batting for them to snuggle into.
Frogs breathe through their skin, whilst under water or during during hibernation, extracting oxygen right out of the water they are surrounded by.
They just push themselves into the mulm or sand or batting and rest there. Bullfrogs and Green Frogs, in particular, do this.
Some small frogs, such as Leopard Frogs, slip into folds in the liner or into the plant pots and survive.

In the end it is the frog will decide where it wants to hibernate the winter out. Some make good choices, some do not! Some make it through winter, some do not!
"Horton"

Correction on the size of our pond as originally posted.
It's 800 gallons not 80. Don't know if that makes a difference at all, but to all responded. Thank you very much.

When I first built my pond, I was afraid the plants on my shelves would freeze. I placed the plants in plastic milk box type containers and lowered them to the bottom of the pond using nylon rope.

I've since learned that the plants were safe on the shelves, but I still sink some of them. Frogs climb into the plant pots to hibernate and the fish spend most of the winter near the plants on the bottom.

Some green frogs also climb into the folds of my liner every winter. You can always look near the bottom and see some frog legs sticking out of the creases.

I've never found a dead frog in my pond.