Boom-arm segment for a concrete pump

A boom arm segment for a concrete pump, having an upper chord (33), a lower chord (34) and two side portions (35, 36) which connect the upper chord (33) and the lower chord (34), wherein the boom arm segment (30) comprises an articulated joint (62) which defines a pivot axis (74) for a pivot connection between the boom arm segment (21) and an adjacent structure (20), wherein the pivot axis (74) is arranged below a plane (63) of the lower chord (34), wherein a transition piece (64) is arranged between the lower chord (34) and the articulated joint (62), wherein a first connection (65) is formed between the transition piece (64) and the lower chord (34), wherein the first connection (65) is spaced apart from the end (61) of the lower chord (34) adjacent the pivot axis (74), wherein the transition piece (64) is enclosed between a first reinforcement portion (40) and a second reinforcement portion (70) which laterally adjoin the transition piece (64), wherein the reinforcement portions (40, 70) each have a lower edge (69) which extends from the articulated joint (62) to the lower chord (34) and wherein the lower edges (69) enclose an angle (68) with the plane (63) of the lower chord (34) which is smaller than an angle (67) which the transition piece (64) encloses with the plane (63) of the lower chord (34).