What are the classifications of trusses?
1、 Triangle truss
Under the nodal load of the triangular truss evenly distributed along the span, the axial force of the upper and lower chords is the largest at the end point and gradually decreases toward the middle of the span; the axial force of the web is opposite.
The triangular truss is mainly used in the roof truss of the tile roof due to the large difference in internal force of the chord and the material consumption is not reasonable.
2、Ladder truss
Compared with the triangular truss, the trapezoidal truss has improved the force of the bars, and it can be more easily used in the truss to meet the technical requirements of some industrial plants.
If the upper and lower chords of the trapezoidal truss are parallel to the parallel string truss, the force of the rod is slightly worse than the trapezoid, but the type of the web is greatly reduced, and it is mostly used in bridges and trestles.
3、 Polygonal truss
Polygonal trusses are also called polygonal trusses. The upper chord is located on the quadratic parabola. The chord is arched to reduce the bending moment generated by the inter-segment load, but the manufacturing is more complicated.
Under the uniform load, the shape of the truss is similar to that of the simply supported beam. Therefore, the force distribution of the upper and lower chords is uniform, the axial force of the web is small, and the material is the most economical. It is a truss form commonly used in engineering.
4、Empty truss
The hollow truss basically adopts the shape of a polygonal truss, and has no oblique web, and is only connected by a vertical web and a vertical string.
The axial force distribution of the rod is similar to that of the polygonal truss, but the bending moment value of the rod end changes greatly under the asymmetric load. The advantage is that there are fewer bars at the intersection of the nodes, and the construction is convenient.
