The vertical and horizontal prefabricated line types of bottom formwork cannot be changed, so the line types of each span must be consistent, which is only applicable to straight bridges without flat curves.

The short-line method has a short production cycle and is suitable for straight bridges and bridges with various spans, especially for multi-span long bridges and flat curved bridges with a large number of segments.

2. The binding methods of steel bars are different.

The utilization ratio of bottom die in long line method is still lower than that in short line method. For segments with varying heights, it is not easy to install internal formwork in the steel framework on the pedestal, so the long-line method generally adopts the method of binding segmental reinforcement on the pedestal, which generally accounts for about 40-50% of the whole segment prefabrication period.

Because both internal and external templates can be easily moved, short-line method is generally used to prefabricate steel skeleton segments on steel tire molds and then hoist them into the pedestal. Compared with the long-line method, the short-line method changes the steel binding process from sequential operation to parallel operation, which greatly shortens the segment prefabrication period.

Extended data:

The short-line method has more advantages than the long-line method. Long-line precast beam segments are still widely used in bridge construction in China. Some of them think that the long-line method has been used for many years, with mature technology and rich experience. Some people think that the short-line method is unfamiliar with the construction technology and requires high prefabrication accuracy, so it is difficult to control the alignment and error with a special calculation program. In fact, most short-line pedestals are manually adjusted by jacks according to the results of calculation programs. It is relatively simple to adjust only the vertical and horizontal coordinate structure, which should be actively adopted.

Because the short-line method has many advantages in improving the accuracy level of linear control and accelerating the production speed, the short-line method is mostly used abroad, and the long-line method is basically not used. Domestic efforts should also be made to popularize the application of short-line beam method, which is very beneficial to improve the quality of bridge construction, shorten the construction period and reduce the construction cost.

Baidu Encyclopedia-Long Line Method