Preface
Prefabricated building structures have been increasingly widely used in construction projects such as multi story residential and office buildings, demonstrating the enormous advantages of prefabricated buildings and becoming a rising star in the field of architecture.
Zhongnan Green Building Group is a national prefabricated construction industry base and a national intellectual property advantage enterprise. The "Technical Specification for Corrugated Steel Plate Composite Structures" (No. T/CECS 624-2019) jointly edited by the company and Tsinghua University after successfully developing the "Corrugated Steel Plate Composite Structure Technology" was reviewed and approved by the Steel Structure Professional Committee of the China Engineering Construction Standardization Association on September 20, 2019, and officially implemented on March 1, 2020. The publication and implementation of regulations provide a new and regulated structural system for the national prefabricated construction industry, and will promote the development process of China's prefabricated construction industry.
The picture shows that Zhongnan Green Building Group has been awarded the title of "National Prefabricated Building Industry Base"
The picture shows the research on the waveform steel plate composite structure system of high-rise buildings by Zhongnan Green Construction Group Recognized by the Hangzhou Urban and Rural Development Commission as a "2020 Hangzhou New Building Industrialization Demonstration Project"
One、 Technical research and development
1. Research and development background: Previously, low rise residential steel structures mostly used keel load-bearing systems, namely box structures, which had the disadvantage of not being suitable for residential buildings with three or more floors; Frame+shear wall/frame+diagonal bracing (buckling restrained bracing, central bracing) structure system is commonly used in the steel structure of high-rise residential buildings. However, the exposed beams and columns caused by the inconsistent width of beam columns and walls affect the appearance and use. The use of slant support also affects the setting of door and window openings. The corrugated steel plate composite structure technology shear wall can overcome these shortcomings.
2. Research and development process: In response to the above-mentioned issues and the defects exposed by traditional technologies and processes, Zhongnan Green Construction Group, together with Professor Guo Yanlin's team from Tsinghua University, established a research and development team. Through research, analysis, and exploration, numerous physical experiments and mechanical analyses were conducted, and then applied in sample rooms, the technology of waveform steel plate composite structure was finally successfully developed.
The picture shows the R&D team conducting experiments
The technology of waveform steel plate composite structure system successfully passed the "High rise Building Waveform Steel Plate Composite Structure System" scientific and technological achievement evaluation meeting on May 14, 2017, attended by academicians such as Dong Shilin, Jiang Huancheng, Zhou Xuhong, Nie Jianguo, Chen Zhengqing, as well as professors and design masters such as Yu Yinquan, Hao Jiping, Fan Zhong, Wang Lijun, and Li Ting. It was unanimously agreed that the overall achievements of the project reached the international advanced level, and the theoretical analysis and experimental research on the waveform steel plate composite structure system reached the international leading level.
The picture shows a group photo of academicians, experts, design masters, and others attending the evaluation meeting
3. Structural principle: The corrugated steel plate composite wall consists of two symmetrically placed corrugated steel plates, filled with concrete, steel tube concrete edge columns, and high-strength bolts connecting the two corrugated steel plates. Its structural layout forms include straight, L-shaped, T-shaped, etc. The edge columns can be made of square steel pipes, H-shaped steel or groove shaped steel, etc. The bolts are arranged at the trough position of the corrugated steel plates in an orthogonal or staggered arrangement, which limits (inward) and restrains (outward) the displacement of the corrugated steel plates, and forms a restraining effect on the concrete through the corrugated steel plates.
The figure shows the combination structure of corrugated steel plates
The figure shows the design and construction effect of the waveform steel plate composite structure
The picture shows a waveform steel plate shear wall steel component manufactured by automation
The picture shows a model house constructed using waveform steel plate structure technology during construction
The picture shows a model house constructed using waveform steel plate composite structure technology
4. Performance advantages: The waveform steel plate composite structure has high bearing efficiency and superior seismic performance. The corrugated steel plate and embedded concrete are connected by through bolts, and the two have a very high combination effect. Due to its waveform shape, the buckling load of corrugated steel plates under compression bending and shear is much greater than that of flat steel plates; The corrugated steel plate is restrained on one side by concrete and restrained by tension bolts, greatly increasing its bending, shearing, and buckling loads. At the same time, concrete is constrained by corrugated steel plates and tension bolts, which greatly improves its strength and ductility.
5. Component production: The waveform steel plate pressing and assembly process consists of equipment cutting, mechanical cold pressing, hydraulic drilling, automatic assembly, automatic welding, automatic coating and other processing technologies, achieving factory automation and intelligent component production.
The picture shows the automated production line of waveform steel plate composite structure steel components (rendering)
Two、 Standardized preparation
On November 6, 2017, at the discussion and exchange meeting on prefabricated structural systems held in Hangzhou, Nie Jianguo, an academician of the CAE Member, and other relevant experts analyzed the new situation, new technology, and future promotion, application and development direction of prefabricated structural system technology research, fully confirmed the achievements of Zhongnan Green Construction Group in the research, development and implementation of prefabricated structural systems, and proposed to promote and implement them as soon as possible.
On May 19, 2018, the kickoff meeting for the compilation of the "Technical Specification for Corrugated Steel Plate Composite Structures" (CECS) jointly edited by Zhongnan Green Building Group and Tsinghua University, with the participation of experts and design masters, was held in Hangzhou. The attending experts and design masters unanimously agreed that the content of the specification compilation is complete, the technology is novel, the theoretical data and calculation formula expression are clear and correct, and it is in line with the application and implementation in high-rise prefabricated steel structure buildings.
The picture shows the scene of the first working meeting of the regulation preparation team
On October 28, 2018, the second working meeting of the regulations drafting group was held again in Hangzhou. Representatives from Central South Green Construction Group, Tsinghua University and other chief editing units, as well as the chief engineer, expert professors, and design masters of the architectural design institute, totaling more than 30 people, attended the meeting.
The picture shows the scene of the second working meeting of the regulation preparation team
On May 11, 2019, the review meeting for the "Technical Specification for Corrugated Steel Plate Composite Structures" (CECS) (draft for review) by the China Engineering Construction Standardization Association was held at the Jianguo Hotel in Baimahu, Hangzhou. After a comprehensive review of the submitted manuscript by the review team, as well as corresponding answers from the chief editor and participating units to the questions raised by the review team leaders and experts, the members of the review team unanimously recognized the "Technical Specification for Composite Structures of Corrugated Steel Plates" (CECS) (submitted for review) and passed the review by the review team.
The picture shows the scene of the review meeting for the Technical Specification for Composite Structures of Corrugated Steel Plates (draft for review)
Three、 Technical Overview
The waveform steel plate composite structural system includes waveform steel plate composite shear walls, steel-concrete columns and steel beams, as well as wall beam nodes. The corrugated steel plate composite wall is composed of two corrugated steel plates connected by tension bolts and filled with concrete to form a composite shear wall. Its cross-section includes a straight, L-shaped, T-shaped, and Z-shaped. The waveform steel plate adopts asymmetric trapezoidal waves, with a thickness of not less than 4mm, a peak of 85mm, a valley of 40mm, a wave amplitude of 35mm, and a wavelength of 180mm. Its technical core is that the waveform steel plate has good compressive and shear buckling bearing capacity. Steel reinforced concrete columns are generally made of finished rectangular pipes, and concrete is poured on site to form composite components. The steel beams are H-shaped steel, which can be hot-rolled steel or workshop welded steel. The waveform steel plate composite wall is an economical and efficient wall structure with the advantages of high bearing capacity and material saving. The traditional construction process of steel plate shear walls has been changed, and corrugated steel plates are used as templates for pouring concrete during the construction phase, achieving prefabricated construction technology. The waveform steel plate composite structural system uses less steel and is more economical than other traditional steel structural systems.
The waveform steel plate composite structure system is suitable for multi story and high-rise buildings, with a building height of up to 100 meters. The technology has been tested through project practice and is mature and cost-effective compared to similar steel structure prefabricated building systems. Compared with traditional cast-in-place technology, the overall cost is basically the same or slightly higher.
Four、 Scope and application conditions of technology
The waveform steel plate composite structural system is suitable for areas with seismic fortification of 8 degrees and below. This system can be applied to high-rise residential buildings, office buildings, schools, hospitals, shopping malls and other building structural systems. The construction height can reach 100 meters. In architecture, it is manifested as shear wall components of the main structure, as well as supporting load-bearing components such as frame columns, frame beams, and floor slabs. The normal construction of this system requires the following conditions: 1. The ability to have a corrugated plate pressing assembly line and conventional steel component processing capabilities; 2. Equipped with conventional tower crane facilities; 3. Capable of pouring self compacting concrete.
Five、 Case Study of Technical Application Projects
1. Hebei Cangzhou Luohu Four Seasons Flower Language 10 # High rise Residential Project: The project started construction in August 2019 and is planned to be completed by December 2019. The project has a construction area of 13165 square meters, a building height of 52.1 meters, 18 floors above ground and 1 floor underground, with a total of 2 units and 144 households. This project is the first project to promote and implement the waveform steel plate composite shear wall technology developed by Zhongnan Green Construction Group in cooperation with Tsinghua University in high-rise residential buildings. The main structure consists of irregular steel tube concrete columns, steel tube concrete column steel beam frame+waveform steel plate composite shear wall structural system, marking the beginning of the application of the prefabricated steel structure technology independently developed by Zhongnan Green Construction Group in high-rise residential projects in China.
The picture shows the production and manufacturing of steel components using this technology in the workshop
The picture shows the construction and installation of waveform steel plate structural components in the high-rise residential project of Building 10 of Four Seasons Flower Language in Luohu
The picture shows the completion of the high-rise residential project on Building 10 of Four Seasons Flower Language in Luohu
2. Hangzhou Municipal Government reserves the land parcel number for transfer [2019] No. 13 plot 1 # and 2 # residential projects: The project adopts a steel tube concrete column steel beam frame+corrugated steel plate composite shear wall structural system, with a total construction area of 35648 square meters. Among them, Building 1 has a height of 78.46 meters and 18 floors (including a 4-story podium). The main building is used for office purposes, while the podium is used for commercial purposes; The building height of Building 2 is 73.65 meters, with 17 floors (including a 3-story podium). The main building serves as hotel rooms, while the podium serves as hotel amenities and commercial facilities. The two towers share a basement, with both embedded ends located on the basement ceiling.
The overall rendering of Plot 1 # and 2 # in Hangzhengchu Chu Chu [2019] No.13 is shown in the picture
Six、 Analysis of Technical Application Benefits
1. The economic benefits of technology promotion: The waveform steel plate composite structure system has the characteristics of high assembly degree, superior structural load-bearing and seismic performance, and highly responds to the national call for the assembly and industrialization of residential structural systems, achieving green and energy-saving of building systems. This system achieves significant social benefits and meets the requirements of sustainable development while optimizing economic benefits. At present, the steel structure residential structure system is vigorously developing in the domestic market, and the existing number of steel structure residential buildings is relatively small. Therefore, the market prospects are broad and the potential is enormous. The promotion of the waveform steel plate composite structure system technology is calculated based on an annual area of 1 million square meters. The enterprise generates a direct economic benefit of 640 million yuan, a profit of 78 million yuan, and an increase in tax revenue of 22.4 million yuan.
2. Economic and social benefits compared to concrete structures: Compared to traditional concrete structures, corrugated steel plate composite structures, with their unique structural stress characteristics and manufacturing features, can generate the following social and economic benefits:
(1) Shortening construction period: adopting factory production and on-site assembly construction, with a construction schedule of 2-3 days per floor, the construction period can be shortened by 1/3 to 1/2;
(2) Reduce capital costs: shorten the construction period, reduce financing and management costs to 0.75-0.85 of traditional structures;
(3) Reduce labor costs: Assembly construction reduces on-site labor by 60% to 70%, and direct labor costs and labor management fees are reduced by 60% to 70%;
(4) Reduce the self weight of buildings: Steel structures have a lighter self weight, and the required bearing capacity of basements is correspondingly reduced. The direct and indirect costs of basements are reduced to 0.8-0.9 of traditional structures;
(5) Increasing the actual usable area of buildings: The waveform steel plate composite structure system significantly reduces the cross-section of steel components compared to traditional concrete structures, increases the usable area inside the building by 5% to 8%, and has the advantage of high occupancy rate. The sales unit price can be appropriately increased by about 5%;
(6) Increase the number of underground parking spaces: With better cross-section of basement components, the number of underground parking spaces will increase by 10% to 20%, and the direct sales revenue of parking spaces will increase by 10% to 20%;
(7) Save financial costs: This structural system is assembled for construction, with fewer concealed works and transparent and controllable quality; Factory standardized production, with dimensions accurate to millimeters; Improving housing quality, early delivery to accelerate capital turnover, and saving financial costs;
(8) Reduce carbon emissions: The waveform steel plate composite structure system adopts new wall materials, with less on-site concrete usage, reducing comprehensive carbon emissions by nearly 40%, and fulfilling corporate social responsibility;
(9) Reduce pollution: Prefabricated construction with less wet work on site, reducing dust, noise, and sewage by more than 80%, achieving civilized construction;
(10) Save water resources: A large amount of tailings quartz sand, fly ash, desulfurization gypsum, etc. are used in the walls to turn waste into treasure, realize the resource utilization of industrial waste, and reduce the waste of natural mining and clay resources; The reduction of wet work and the production of new materials in factories effectively reduce the waste of water resources, and the groundwater source at the construction site can basically meet the needs of construction operations;
(11) Improve user comfort: The system is manufactured in a factory and assembled on-site for construction, achieving four energy savings and one environmental protection, meeting the requirements of green buildings; Compared with traditional concrete structures, steel structures have better ductility and seismic performance, providing users with a safe and comfortable living environment.
3. Compared with the steel pipe bundle structure system and the box steel plate wall structure system, the corrugated steel plate composite structure system can generate the following economic and social benefits:
(1) The amount of welding work in the workshop has been significantly reduced, and the cost of welding materials and labor can be reduced by about 60%. The direct environmental negative benefits can be reduced by about 60%;
(2) The enclosure system adopts composite walls with bolted connections, and the construction process does not require welding, which accelerates the construction progress and greatly reduces the direct cost of maintaining the system;
(3) The enclosure system adopts bolted connections, which greatly reduces the risk factor of high-altitude operations;
(4) The seismic performance of the enclosure system is significantly improved compared to the performance of welded connections, truly achieving a century old residence.
Seven、 Future prospects
With strong support from national policies, prefabricated buildings have become the preferred choice for project construction nationwide. The application of corrugated steel plate composite structure technology can improve efficiency and reduce costs. With the acceleration of urbanization and relevant national policy support, the market for prefabricated residential buildings will become increasingly large and the prospects will become broader; At the same time, with the acceleration of economic development and construction in countries along the the Belt and Road, the demand for prefabricated buildings in foreign cities will also be growing. The corrugated steel plate composite structure technology can better meet this demand, which can be produced at home and assembled abroad, greatly reducing the construction amount and duration of overseas operations, and effectively protecting the surrounding environment, further demonstrating the strong advantages of Chinese construction.