If the condo association is responsible for structural repairs and is not fulfilling their legal obligation, the way to force them to do so is by filing a legal action seeking injunctive relief--a court order requring them to make the repair--based on the deed, HOA agreement, or other document obligating them to do this. The best way to get this done is to let an attorney file the action for you. If you want to do it yourself, then you can--contact your county court to find instructions and templates or sample forms.