Cantilever form traveler casting construction has become the core mainstream technology for cross river, cross valley and high pier bridges. As the core load  bearing and working equipment for cantilever construction, the form traveler's structural stability, mechanical performance, operating space and safety factor directly determine bridge construction quality, efficiency and on site safety control level. At present, triangular form travelers and diamond form travelers are widely applied on bridge construction sites. They differ in structural design, mechanical mechanism and construction adaptability, and improper selection often leads to poor adaptability. This article sorts out the standard construction procedure of form  travelers, conducts a comprehensive comparison between triangular and diamond form travelers from structural form, stability, operating space, construction safety and mechanical characteristics, and summarizes their advantages and applicable scenarios.

Diamond Form Traveler

Triangular Form Traveler

1 Construction Procedure

The general construction procedure of form  traveler is as follows: form  traveler moving and positioning → installation of bottom formwork and side formwork → installation of bottom plate and web reinforcement and reserved ducts → installation of inner formwork → installation of top  plate reinforcement and reserved ducts → concrete pouring → curing → threading of prestressing steel strands and anchorage tensioning → duct grouting → form  traveler lowering and stripping of bottom formwork → form  traveler forward moving.

2 Comparative Analysis of Structural Forms

Both triangular and diamond form travelers feature simple structure, clear force transmission, high overall rigidity, low deformation risk and convenient movement. The triangular form traveler mainly consists of main truss, suspension system, anchorage system, bottom formwork platform and travelling system. Conventional materials are adopted. With reliable quality of fine rolled threaded steel bars, the suspenders made of such bars feature simple fabrication and low cost. The travelling track is anchored by vertical prestressing fine  rolled threaded bars on the web plate, which delivers reliable force bearing and reduces construction cost. The two types of form travelers are basically consistent in structural form and material selection without obvious differences.

2.1 Structural Stability Analysis

The front lifting point of the triangular form traveler is lower than that of the diamond form traveler. From the perspective of spatial structural stability, the triangular form raveler performs better. It has far fewer transverse connections between main trusses and shorter front suspenders, which helps save materials.

2.2 Operating Space Analysis

The front lifting point of the diamond shaped form traveler is significantly higher, offering larger working platform space for constructors. It facilitates installation of form traveler tracks, embedding of vertical prestressing components and binding of web reinforcement, so as to improve construction speed.

2.3 Construction Safety

The front cross beam of the triangular form traveler is relatively low, so operations on the front cross beam have a higher safety factor compared with the diamond shaped form traveler, showing superior safety performance.

3 Comparison of Mechanical Performance

In terms of spatial geometric composition of structural members, both form  travelers are composed of two right angled triangles. For the diamond shaped form traveler, one right angle side of the triangular member is on the upper part and the other on the lower part; for the triangular form traveler, both right angle sides are located at the lower part. Under external load P, each member bears tension or compression differently. See Figure 1 for the mechanical calculation sketch and Table 1 for internal forces of each member calculated by truss mechanical method.

Figure 1 Mechanical Calculation Sketch of Triangular and Diamond Form Travelers

Table 1 Force Conditions of Members for Triangular and Diamond Form Travelers

According to comparison data in Table 1: Member 1 of the diamond form  traveler is under compression, while Member 1 of the triangular form traveler is under tension with identical force magnitude. Member 2 of the diamond form traveler is under tension, while Member 2 of the triangular form traveler is under compression with identical force magnitude. Members 4 and 5 bear equivalent forces. The most remarkable difference lies in Column 3: the force borne by Column 3 of the triangular form traveler is twice that of the diamond  shaped one. The comparison indicates that the column of diamond form  traveler has better mechanical performance.

Conclusion

Both triangular and diamond shaped form travelers realize convenient travelling. The triangular form traveler bears larger member forces and provides lower working platform height. Nevertheless, it has lower force bearing points and better stability. Both types feature simple force transmission, easy fabrication, rapid installation and high recycling value. Therefore, cantilever construction with form travelers is increasingly widely applied in bridge engineering. Form  traveler products are developing toward lightweight, while sufficient rigidity and strength shall be guaranteed to maintain structural stability and prevent member instability induced engineering accidents, so as to enhance safety, quality and construction speed of bridge cantilever works. Multiple factors and site conditions shall be comprehensively considered for form traveler selection to achieve expected construction objectives.

Shandong Boyoun Heavy Industry is a professional original manufacturer integrating R&D, design, production and technical services for bridge cantilever form  travelers. With over 20 year experience in form traveler equipment, it specializes in structural optimization, mechanical checking calculation, customized design and on  site construction adaptation for triangular, diamond  shaped and other form  travelers. Optimal solutions can be tailored for projects with different spans, girder types and construction conditions. The company provides one  stop services including pre project selection consultation, mechanical verification, drawing optimization, manufacturing, on site installation guidance, technical disclosure and after  sales maintenance, to solve project pain points such as difficult form traveler selection, potential construction hazards and poor precision control. Construction enterprises and project teams are welcome for consultation and business cooperation regarding form traveler selection, technical support and customized manufacturing requirements.