Abstract: A data sensor comprises a carrier member consisting of metal and shaped as a hollow section (1) and subdivided into adhering sections (2 and 3) and a measuring section (5). The adhering sections carry annular discs (4) and the measuring section (5) has strain gauges (6 and 7) arranged in mutually diametrically opposing positions. Within the area of the measuring section (5) the strain gauges (6 and 7) connected with the periphery of the carrier member are covered by an insulating mastic (8) with a self-welding tape (9) wound therearound. A shrinking hose (10) is provided as an outermost cover for the measuring section. The ratio of the cross-sectional area (F.sub.B) defined by the outer contour of the hollow section (1) and the cross-sectional area (F.sub.M) of the material of the hollow section are selected to equal the ratio of the coefficient of elasticity (E.sub.M) of the material of the carrier member and the coefficient of elasticity (E.sub.B) of the concrete (FIG. 1).