extend vertically in the center of the pier 12 triangular framework 22 of three cross beams 22 a 22 b and 22 c are suspended to make contact with the sidewall 11 this suspension is enforced by three saddle members 23 adjustably threaded to the nut 21 of the pier 12 through a rod 24 which has corresponding threads formed on its outer faces and is welded to the bottom of the saddle member 23 as shown in detail in fig3 thus the saddle member 23 threaded rod 24 and nut 21 together constitute a saddle jack assembly 25 for buttressing the cross beams 22 a 22 c at their junctions referring further to fig4 the saddle member 23 with rod 24 of the saddle jack assembly 25 is adapted to be transported as a loose component to the construction site where it is assembled with the cross beams as well as the corresponding pier the cross beams 22 a 22 c have a common structure so that they can be interchangeably laid to extend between any two saddle jack assemblies 25 forming the triangular framework 22 in a right handed configuration the four walls cooperate two of them holding a right supporting beam and two of them holding a left supporting beam the right supporting beam extends beyond the end of the left supporting beam because they are identical the beams can be interchanged and the saddle jacks can also be interchanged the top of view of the saddle jack shows that the configuration can be reversed so that the left beam protrudes beyond the end of the right beam so that the.