One of the concrete structures cracks during construction. The other doesn't crack during construction; but, it cracks after construction, when external loads are applied.
What does this tell you?
The cracks that occur in the structure when external loads are applied are obviously load-related. Such would be the case if the structure is inadequately designed for torsion. The external loads would cause the inadequately reinforced (for torsion) structure to crack. In such a case the cracks are more likely to be local. For example, cracks resulting from inadequate reinforcement for torsion will typically appear near a free edge, where external walls or adequately reinforced (for torsion) edge beams are not present. Such cracking would typically not spread beyond the free edge to interior columns.
However, cracks that occur in the other identical structure during construction, before external loads are applied, are obviously due to something other than external loads. Such would be the case if the structure was inadequately designed for temperature change, i.e. has NO expansion/contraction joints. Cracking in a large structure without expansion/contraction joints would not be restricted to just one part of the structure, e.g. slabs or beams, but would be present throughout--slabs, beams, girders and columns.
Cracks in the yet-to-be-opened Silver Spring Transit Center appeared during construction before external loads are applied. They are extensive. Slabs, beams, girders and columns are severely cracked. It's obvious that these cracks are not the result of torsion. Torsion occurs when external loads (fully loaded buses) are applied. The widespread cracking in the unopened Silver Spring Transit Center are the result of something else: temperature changes and the complete lack of expansion/contraction joints, bad concrete, poor construction, woefully inadequate design (inadequate reinforcement for the structure to hold itself up), or all of the above.
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