ZERO STIFFNESS IN DIRECTION 5 AT JOINT    421 EQN.NO.     221
          LOADS APPLIED OR DISTRIBUTED HERE FROM ELEMENTS WILL BE IGNORED.
          THIS MAY BE DUE TO ALL MEMBERS AT THIS JOINT BEING RELEASED OR
          EFFECTIVELY RELEASED IN THIS DIRECTION.
    ZERO STIFFNESS IN DIRECTION 6 AT JOINT    421 EQN.NO.     222
    ZERO STIFFNESS IN DIRECTION 5 AT JOINT    417 EQN.NO.     245
    ZERO STIFFNESS IN DIRECTION 6 AT JOINT    417 EQN.NO.     246
    ZERO STIFFNESS IN DIRECTION 5 AT JOINT    411 EQN.NO.     299
    ZERO STIFFNESS IN DIRECTION 6 AT JOINT    411 EQN.NO.     300
    ZERO STIFFNESS IN DIRECTION 5 AT JOINT    407 EQN.NO.     323
    ZERO STIFFNESS IN DIRECTION 6 AT JOINT    407 EQN.NO.     324
    ZERO STIFFNESS IN DIRECTION 5 AT JOINT    422 EQN.NO.     377
    ZERO STIFFNESS IN DIRECTION 6 AT JOINT    422 EQN.NO.     378
    STAAD SPACE                                              -- PAGE NO.    8

    ZERO STIFFNESS IN DIRECTION 5 AT JOINT    418 EQN.NO.     413
    ZERO STIFFNESS IN DIRECTION 6 AT JOINT    418 EQN.NO.     414

   **WARNING - THERE WERE MORE THAN 12 DOF WITH ZERO STIFFNESS.
               THE FIRST 12 ARE LISTED ABOVE.
               TOTAL # TRANSLATIONAL=      0 TOTAL # ROTATIONAL=     40

多半是约束释放，或者桁架构件交叉

约束释放过多，释放约束时，如果是铰接构件，不要释放Mx