Reduction of Constraints which Are Imposed through Rigid or Near-Rigid Supports

Most constraints of this type are unintentional, such as the result of non-uniform foundation settlements. They are very markedly reduced by creep. This is desirable in the case of settlement, but it is undesirable in those cases where the constraint was created on purpose in order to improve the distribution of action effects. For this reason, an artificially created constraint is used only in exceptional cases when the supports are near rigid.