A good bike shop will ensure that the final assembly is sound. Junk bikes from non-bikeshops are the worst you can get.
Any bike from a reputable brand will have frame and components strong enough for you.
The weak point is usually the wheels. Generally, the more spokes you have the stronger your wheel. 32 spokes is quite common but 36 is recomended for heavier duty use.
The quality of the wheel built is also important. Factory wheels are often built by machine. A hand-built wheel (with the same components) will usually be much stronger and more reliable.
Get your bike from a proper bike shop where they can check and tune the wheels.