As strong as

Hi,

I just want to know which sentences below is acceptable.

1. The use of steel cables would be six times stronger than needed to support the bridge.
2. The use of steel cables would be six times as strong as needed to suppor the bridge.
3. The use of steel cables would be six times stronger as needed to supoort the bridge.
4. The use of steel cables would be six times as stronger than needed to support the bridge.
5. The use of steel cables would be six times as more strong than needed to support the bridge.