GQJS( Bridge Structure Design System abbreviated as GQJS according to the Chinese phonetic alphabet )had been developed by the combined effort of many experts in the Ministry of Communications. The predecessor of GQJS is GQZJ (Bridge Synthesis Program abbreviated as GQZJ according to the Chinese phonetic alphabet ).GQZJ had been applied tentatively since 1978 and passed the technical appraisal by the Chief Bureau of Highway of the Ministry of Communications in 1980. During the last 20 years of spread and application of the program in highway system, it was used extensively and verified in the actual engineering with continuously modified and perfected by many bridge experts. Now, we developed English version of GQJS as BSDS (Bridge Structural Design System). 

This system is suitable for any bridge structure system which can be simplified as a plane bars system, such as simple supported beam bridge, Continuous bridge, continuous beam bridge, continuous rigid frame bridge, continuous arch bridge, truss structure, T - rigid frame bridge, cable-stayed bridge and frame structure, etc. Bridge materials may be prestressed concrete, reinforced concrete, concrete, steel, masonry and the combination of the above materials. For different structural members, users can select different materials. The structure system can be formed by phases. Every phase has its own static model. For the current construction method such as cantilever-construction, push-out construction and temporary support assembling construction, the system can comprehensively analyze the structure system at construction phase and using phase. The eccentric beam element with rigid arms on both sides was adopted by the system, so the effect of nodal rigid domain where the multiple poles meeting was considered.

The calculating loads in the construction phase are as follows: system adjustment (including the poles getting back work and the replacement of support abutment during the push-out construction), the stretching of prestressed bars, the disassembling of temporary prestressed bars, structural weight, concentrated load, distributed load, forced displacement, unloading the element, disengaging work of unilateral forced pole, secondary internal force and prestress loss due to the concrete shrinkage and creepage, etc.

The calculating loads at the phase of use are as follows: all the static loads: concentrated load, distributed load, forced displacement, temperature variation (including the friction load resulted from the sliding of support abutment), and all the live loads: the vehicle loads as automobile-15, automobile-20 and super automobile-20, the automobile loads for urban bridges (Grade A and B), any automobile group, the trailer load as trailer-80, trailer-100, trailer-120, special vehicle load, full-bridge crowd load, footpath crowd load.

The calculation of the system includes: internal forces for each phase, accumulative internal forces, normal stress, shear stress, principal stress and their directions of six points along the height of the section, stress of the prestressed bars after stretching and anchorage, stretching elongation of the prestressed bars, residual stress of the prestressed bars for each forcing phase, section stress due to the nonlinear temperature field along the height of section, section internal force, displacement, stress and their combinations due to all kinds of loads at use phase. All output results titled with Chinese specification for reading and comprehension. The static calculation sketch, the deflection graph and the stress envelope diagram for the construction phases can be plotted according to the demands of the users.

The system has been used in the many design items such as: Nanping Bridge in Fujian province(60m+95m+60m continuous rigid-frame bridge), Rencungou Viaduct in Henan province(5×45m thrusting continuous bridge), Shantou Bay Bridge in Guangdong province(444m cable stayed bridge scheme), Luofushan Bridge in Guangdong province(100m tied arch bridge), Luowei Bridge in Guangxi Autonomous Region(80m+125m+80m continuous rigid-frame bridge), Yuanjiang Bridge in Yunnan province(55m+182m+265m+194m+69m continuous rigid-frame bridge) etc. It has been also used for the many detection and retrofit items of the old bridges: The Third Bridge on Qiantang River in Hangzhou(cable stayed bridge), two steel truss bridges in Bingzhou and Pingyin, Shandong province, and the double arch bridge in Chahe, Shandong province etc. It got excellent effects and users' confirmation. The engineering examples above list are only few parts of the actual approbation. Bridges designed by using this system are too many to list in details.

During the exploitation of this software, the technology of dynamic visualized interactive interface and intelligentized automatic building of  structure data is adopted. Under the 32-bit Windows 95/NT operating system, the advanced and efficient tools for the software exploiting—Fortran Power Station 4.0 and Visual Basic 5.0 are adopted. 

In the interactive interface of this system,  file View, data table and function buttons are equipped with a great deal of dynamic pictures. The interfaces were active, visualized and convenient for filling data. The data inputted are categorized according to the bridge structure members and the loading condition. Abundant help information in the interface is convenient for different levels of users. Help information includes system functions, applying method and the detailed explain for all parts of input information. In conclusion, the system have the virtues of friendly interface, simple data input and visual and pellucid results output. Within the domain of bridge design, this software is an available tool with strong functions and advanced technology.