Lower vehicle-body structure of automotive vehicle

A lower vehicle-body structure of an automotive vehicle, comprising:

• a floor panel having a tunnel portion which extends in a longitudinal direction at a center, in a vehicle width direction, of the vehicle;
• a pair of right-and-left floor frames provided on a lower face of the floor panel to interpose the tunnel portion therebetween;
• and
• a pair of right-and-left tunnel side members extending along the tunnel portion at respective positons which are located on an outward side, in the vehicle width direction, of the tunnel portion and on an inward side, in the vehicle width direction, of the floor frames,
• wherein an auxiliary device is provided below a portion of said floor panel which is positioned between one of said floor frames and one of said tunnel side members, a member which extends in the vehicle width direction and straddles said one of the floor frames and the other tunnel side member which is opposite to said one of the tunnel side members is attached, and a yield strength of the vehicle width direction of a tunnel corresponding portion, in a width direction, of said member which corresponds to the tunnel portion is set to be lower than that of an auxiliary-device corresponding portion, in the width direction, of said member which corresponds to the auxiliary device,
• said member is configured such that said tunnel corresponding portion and said auxiliary-device corresponding portion are integrated, and the auxiliary-device corresponding portion has a greater width, in the longitudinal direction, than the tunnel corresponding portion,
• said tunnel corresponding portion of the member has a constricted portion which is configured such that an inward side, in the vehicle width direction, thereof has a narrower width, in the longitudinal direction, than an outward side, in the vehicle width direction, thereof, said auxiliary-device corresponding portion of the member is configured to substantially linearly extend along the vehicle width direction, and said member is attached such that the auxiliary-device corresponding portion is offset toward said constricted portion of the tunnel corresponding portion in the longitudinal direction,
• said auxiliary device is provided on either a right side or a left side of said tunnel portion, and an end portion of said member is connected to said other tunnel side member.