Not saying that you can't get corruption due to any random shutdown. But I do feel that a lot has to do with what you're doing, or not at the time. I.e. we have systems at work which we leave up all the time. We do not have power backup, and therefore we lose power, most systems shutdown, unless they're laptops and then they shutdown after their batteries run dry.
Most systems (if left in default configurations) will go to standby or hibernate after long periods of non-use. This is good and will protect your system because things like the disk will not be in active use should the power go off.
However if you're actively copying large quantities of data and the power gets yanked, then you stand to lose a lot of that data you were moving, in and around the power failure time.
If it's critical data, or deemed by you to be; then eSelix and CodeFreaker have already told you what to do. But I also say be aware that a UPS is only going to get you so far. If it's a work system, power goes away for 24+ hours and it happens on the weekend, there's no guarantee that a UPS is going to supply enough power to keep it going.
Curious. What do you mean "forced shutdown"? That implies something other than power interruption. Forced shutdown is you locked it up and had to hold the power button long enough to cause it to shutdown? Avoid that at all costs and instead try to figure out what's happening to place you into that situation. There likely are some remedies you can follow which can at least free up the system enough so that you can perform a proper shutdown.