Company Name: Shaanxi Ningde Construction Engineering Co., Ltd.
Contact: Ms. Zhang
Address: Room 2731, Block B, Yanxiang City Plaza, 56 Jinye 1st Road, Xi'an
Company Name: Shaanxi Ningde Construction Engineering Co., Ltd.
Contact: Ms. Zhang
Address: Room 2731, Block B, Yanxiang City Plaza, 56 Jinye 1st Road, Xi'an
Promoting the construction of highway steel structure bridges is an important grasp in implementing the concept of green development and implementing modern engineering management with humanization, professionalism, standardization, informationization, and refinement. It can effectively improve the quality of highway bridge construction and improve the safety and durability of the structure. , Reduce the life cycle cost, promote the transformation and upgrading of highway construction, improve quality and efficiency.
At present, the promotion of steel structure bridges inside and outside the highway industry is very popular, and some provinces have begun pilot work and achieved good results. In the first half of this year alone, Gansu, Hebei, Hunan and other provinces have organized and held steel structure bridge seminars, which have attracted great attention from all aspects of the industry. Design institutes with relatively high technical level in China have already started relevant research, and some units have begun to study the compilation of general maps for medium-span steel bridges. In addition, China's steel structure manufacturing enterprises have strong strengths. Under the guidance of policies, the production capacity of steel structure bridges will be adequately guaranteed. At this stage, the biggest obstacles to the promotion of steel structure bridges are the construction cost and inertia thinking. According to estimates, for small and medium-span bridges, the construction cost of concrete structures is relatively low, but as the bridge span increases, the cost advantage of steel-structure bridges begins to appear. From the perspective of the entire life cycle, the cost and durability advantages of steel bridges are more prominent. To this end, the Guiding Opinions clearly stated that we must adhere to the principle of policy guidance and market-oriented advancement, and the government mainly plays a role of policy guidance. Localities should formulate development technology routes according to actual conditions and local conditions, and give better play to market initiative. Orderly advance the construction of steel bridges. It is necessary to select projects with suitable conditions for trial and demonstration, summarize experiences, revise and improve relevant standards and specifications, and gradually promote the construction of steel bridges. The construction of steel structure bridges is not limited to newly-built projects, and engineering projects such as reconstruction and expansion of bridges and dangerous bridges can also use steel bridges instead of concrete bridges.
The guidance points out that through five years of hard work, the design, manufacturing, construction, and maintenance technology of steel structure bridges in China's highway industry will be basically mature, and the technical standards will be more complete. The proportion of conventional bridges in the project using steel structure bridges has been significantly increased.
Second, attach great importance to the key issues of steel structure bridge construction
Promoting the construction of highway steel structure bridges is a systematic project and a major technical policy. To implement the Guiding Opinions, we must respect science, pay attention to methods and methods, act in accordance with objective laws, and proceed in an orderly manner. Don't rush into a hurry, blossom regardless of the actual situation, blindly advance, causing unnecessary losses and negative effects. To this end, the Guiding Opinions clarified seven requirements.
The first is to strengthen the selection and comparison of bridge structure plans. Promoting the construction of steel structure bridges is not to exclude concrete structure bridges, but to choose the appropriate bridge type structure under appropriate circumstances, and give play to the comparative advantages of various structures to achieve the purpose of reducing the life cycle cost of the project and improving the quality of the project. In promoting the construction of highway steel structure bridges, we must emphasize the comparison and selection of bridge schemes.
In the feasibility study and preliminary design stage of highway construction projects, comprehensive comparison and selection of various technically satisfying and economically feasible bridge structures should be conducted. The comparison and selection must not only consider the construction cost, but also consider the project environmental conditions and maintenance costs. Factors such as project implementation risks. The comparison plan should include both concrete T-beams and box beams, as well as steel structures such as steel box beams, steel truss beams, and steel-concrete composite beams. From the engineering experience, the characteristics of light weight steel bridges, especially in extra-long-span bridges and bridges in high seismic intensity areas, have obvious advantages and should be preferred. For bridges with special shapes such as curved slopes, the stress conditions are complex, and the advantage of isotropic steel is suitable. Steel structures should also be preferred. For other bridges, including new construction, reconstruction and extension projects, and bridges with demolished superstructures in reconstruction of dangerous bridges, etc., you should choose a suitable steel structure or concrete structure bridge for a comprehensive comparison based on its span and environment, and choose the best one. .
In the technical and economic comparison and selection, special attention should be paid to the actual conditions of the project construction, to avoid forcibly advancing a structural bridge if conditions are not available, and unnecessary increase of construction costs, causing hidden safety risks.
The second is to do a good job in the selection of steel structure bridges. Steel structure bridge superstructure mainly includes steel truss girder, steel box girder and steel composite composite beam. Steel truss girder is a traditional type of steel structure, with strong adaptability, clear structure force, easy inspection and maintenance, occupying a long span for a long time. The bridge has an advantageous position, but its steel consumption is relatively large and its cost is relatively high. The steel box girder structure has a relatively light weight and good stability under the action of cross wind, but the internal stress state of the structure is complex, the internal inspection and maintenance of the box girder are difficult, and the maintenance costs are relatively high. The fatigue problem of the steel bridge deck still needs further research. Improve. The steel-concrete composite beam structure exerts the compressive performance of the concrete material and the tensile performance of the steel, and avoids the fatigue problem of the steel bridge deck paving. The advantage is obvious in medium-span bridges. Each type of structure can be divided into multiple structure types according to the detailed structure differences, and each structure has its own characteristics and scope of application. Reasonable selection has a great impact on better adapting to the natural environment of the bridge structure, improving the safety and durability of the structure, and reducing the life cycle cost. In specific work, the most suitable bridge structure should be selected in accordance with the actual situation of the project. , Give full play to the structural characteristics, make strengths and avoid weaknesses, to achieve the best results.
The third is to strengthen the structural design of steel bridges. Steel bridges have small cross-sections, and structural design has a significant impact on the safety and durability of bridge structures. According to the structural characteristics of steel bridges, the detailed structural design should be focused on. It is necessary to strengthen the detailed design of joints, section transitions and connections to achieve a continuous and balanced structure, avoid sudden changes in section and excessive stress concentration, and reduce structural fatigue damage. To address the problem of corrosion resistance of steel structures, we must improve the design of the drainage system to ensure that it does not leak and prevent the bridge surface from corroding the steel structure. We must emphasize refined design in terms of material selection, structural design, construction and installation of drainage systems . According to the characteristics of light weight of steel structure bridges, the design and check calculation of the anti-overturning structure of the superstructure should be strengthened to ensure the stability of the structure. It is necessary to improve fire protection measures and improve the structure's ability to respond to fire.
In recent years, the steel industry has made a lot of efforts to improve the resistance of steel to natural environment corrosion, and weathering steel is one of the typical results. The production cost of weathering steel is not much higher than that of general steel, but it can rely on its own properties to resist erosion in the general environment, and even achieve painting-free, which can greatly reduce the maintenance cost in the later stage. Steel bridges in the United States and Japan have begun to widely promote weathering steel. China currently has the production capacity of weathering steel and has begun to export to foreign countries. This is a material worth promoting. According to relevant media reports, the domestic weathering steel has already started the solid bridge test and achieved good results.
The fourth is to do a good maintenance design of the steel structure. The timely detection of diseases and timely maintenance are of great help to improve the durability of bridge structures. Steel structure bridges have more advantages than concrete structures in improving structural construction measures. When designing a steel structure bridge, the maintenance structure should be taken as a necessary content of the bridge structure design, and overall consideration should be made to ensure that the components are reachable, inspectable, repairable, and replaceable to better ensure the service life and safety of the structure. The management and maintenance units of steel structure bridges shall improve the maintenance management system, strengthen the maintenance in a targeted manner, be equipped with management personnel and equipment, improve the level of management and maintenance, and ensure the safe operation of the bridge and the durability of the structure.
The fifth is to promote the industrialization, standardization and intelligent construction of steel structures. Steel structure bridges are suitable for factory manufacturing, industrial production, and assembly construction, and are in line with the development trend of modern bridge construction. Through structural standardization and intelligent processing, the construction quality of steel bridges should be better improved, construction costs should be reduced, and production efficiency should be improved. Beginning from the design stage, consider all issues such as standardized design of steel bridges, factory manufacturing, and assembly construction, and reasonably divide components and sections. Special design is required for the on-site assembly solution. Welding connection, bolting, riveting and other methods can be used on-site assembly to minimize welding and anti-corrosion coating at the construction site, enhance the convenience of construction operations, and ensure quality durability.
Sixth is to strengthen the revision of standards and norms and the training of talents. At present, the standards and quotas for steel structure bridges in China's highway industry are basically complete, and personnel and technical reserves basically meet the needs of construction. However, from a practical point of view, because highway steel bridges are currently mainly used for extra-long-span bridges, the design and construction experience of long-span and medium-span bridges is relatively small, and the quota determination time is also earlier, and there is a certain gap with actual applications. It is necessary to give play to the strength of the participating units and use market mechanisms to continuously accumulate and improve. The Ministry of Transport will also actively organize and promote the formulation and revision of standard quotas.
Seven is to optimize the organizational form of construction. The design of steel bridges should be closely coordinated with manufacturing and processing, and their respective advantages should be better exerted. The traditional concrete structure bridge construction generally adopts the on-site prefabrication or cast-in-place method, and its contracting method can no longer meet the requirements of industrialized manufacturing of steel structure bridges. For this reason, the Guiding Opinions clearly states that steel structures encourage the contracting of design and construction (including manufacturing) general contracting, promote the deep integration of design, construction, and manufacturing, and maximize the advantages of steel bridges. Aiming at the professional characteristics of steel structure bridge maintenance, it is encouraged to adopt a professional maintenance outsourcing method to improve the quality of steel structure bridge maintenance and reduce the life cycle cost.
Third, give full play to all aspects of strength
To promote the construction of steel structure bridges as a major technical policy for the highway industry, it is necessary to strengthen organizational leadership, change the inherent concepts of the past, mobilize various forces, and form a joint force in the industry. The Guidance states that:
Provincial transportation authorities should strengthen their leadership in this work, analyze the actual situation of bridge structural characteristics, technical reserves, steel structure manufacturing conditions, and construction experience in the region, and study the establishment of a suitable combination of regional economic and social development requirements and resource endowments. The working mechanism and technical route for the promotion and application of steel structure bridges in the region are summarized on the basis of pilot experiments and gradually promoted.
Provincial transportation authorities should gradually establish a credit evaluation system for steel structure bridge component manufacturing units, and take credit management as an important means of market management and improve project quality. The Ministry of Transport will incorporate the credit evaluation of steel structure manufacturing units into the credit evaluation system of the highway construction industry in a timely manner according to the implementation effect of credit evaluation.
According to the actual situation of the project, the project construction unit shall analyze the applicable conditions of the steel structure and the key issues that need to be solved in the application of the steel structure, organize a special study to form practical results, and guide the project construction. It is necessary to gradually complete steel structure bridge construction technology through a period of technology accumulation. In advancing the construction of highway steel bridges, highway construction, design, construction and other units must make full use of market and social forces, give play to the wisdom of experts, and provide technical support and guarantee for the advancement of steel bridges.
The compilation of steel structure standard diagrams is an important measure to promote the construction of highway steel bridges at this stage. The Ministry of Transport will actively support capable design units and steel structure manufacturing units to work together to prepare standard plans for steel structure bridges and promote the popularity of steel structure bridges.