Yes, you can walk on it
Anything bigger treats the barrier as a normal physical wall.
As far as RAW, there is no explicit limit for weight, even for glass, but I would strongly recommend looking at the "carrying capacity" rules on page 420 the Barrier Ratings table on page 197 for comparable materials for the durability, although the only real mention is for when something actually tries to deal damage to the barrier itself. What it does say is that a weapon doesn't penetrate a barrier at all if it's damage value is less than the Armor rating, which to me indicates that unless something is trying to break it, as long as it meets those dimensions it won't break without GM caveat (see below section) since even heavy objects aren't treated as implicitly dealing damage to anything. Perhaps the GM could imply that too much weight counts as a penetrating weapon and deals minor damage to the structure and causes them to fall through.
Suggested Non-RAW Solution:
Characters can carry their Strength x 10 kilograms in weight without any sort of test—this is your carrying capacity. Lifting and carrying more calls for a Strength + Body Test. Each hit increases the weight you can carry by another 10 kilograms.
With this, I would treat every 10kg on an item as 1 damage trying to break the object. So glass could hold 20kg but instantly breaks at 30kg. An old door (S: 2, A: 4) could hold 50kg once and only once as the material cracks and groans. Up to 40kg is sustainable as long as that last point remains. However, this is entirely guesswork since I haven't seen rules yet pertaining to actual weight limits. But it would make sense for concrete to hold 200kg without problem (Armor 20).