1.Triangle truss

Under the nodal load distributed evenly along the span, the axial force of the upper and lower chords is the largest at the end point and gradually decreases toward the span; the axial force of the web is opposite. The triangular truss is mostly used in the roof truss of the tile roof due to the large difference in internal force of the chord and the unreasonable material consumption.

2.Trapezoidal truss

Compared with the triangular truss, the force of the bars is improved, and it is easier to meet the technical requirements of some industrial plants in the truss. 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

Also known as a folding line truss. 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 shape of the polygonal truss is basically adopted, and there is a straight line between the upper chord nodes, and there is no oblique web, and only the vertical web is connected with the upper and lower strings. 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.