The ornamental design for a transportstructure, as shown and described.
FIG. 1 is a perspective of the transport structure;
FIG. 2 is a front elevational view of the transport structure;
FIG. 3 is a rear elevational view of the transport structure;
FIG. 4 is a left side elevational view of the transport structure;
FIG. 5 is a right side elevational view of the transport structure;
FIG. 6 is a top plan view of the transport structure; and,
FIG. 7 is a bottom plan view of the transport structure.
The broken lines shown in the figures are included for the purpose of illustrating portions of the transport structure and forms no part of the claimed design.