Structural materials industry development status of foreign film

Modern film structure was originally developed in Germany, its basic characteristics, mechanical characteristics,

design methods and potential as a structural system is also in Germany. Montreal German Pavilion, International

Exposition 1967 German design, and construction of membrane structure material, with a wide range of international

influence in the history of architecture. Membrane structure has become the integral part of modern architecture, the

construction of a number of well-designed membrane structures around the world.

Since 2002, China has PVC membrane structure material, PTFE membrane structure material and PVDF R & D and production

through the introduction of advanced technology and equipment in developed countries. However, since the application

time is short, the low level of technology, equipment limitations, the production efficiency is low, the product

physical properties (such as the self-cleaning properties, life) and mechanical properties (such as tensile strength,

tear resistance) with foreign the product has a larger gap, have become the film materials industry products to

enhance and broaden the urgent need to address the key issues in the application process At present, the annual

structural materials required for high-performance film more than 40 million tons (400 million m2), still 90%

dependent on imports.

The development of the membrane structure

In 1961, AIA magazine published the article of the "Tent", reveal to the people the importance of the membrane

structure, research and development from the perspective of building a modern structure of the film attracted

worldwide attention, represents the starting point of modern film structure , its technology and ideas reflected in

the 1967 World's Fair in Montreal, the epoch-making sum in the course of development of the membrane structure.

International Exposition held in Osaka, Japan, in 1970, many Japanese architects began to film new material to create

a new unique space provides an excellent opportunity to explore the potential of the membrane structure. Inflatable

membrane structure, the Expo USA Pavilion is low span ratio (relatively flat) is a milestone in the history of

development of the inflatable membrane structure.

In the 1970s, Geiger Berger developed inflatable membrane. Followed by a PTFE-coated glass fiber membrane become a

new type of membrane material, many giant membrane structure in the United States, such as the Pontiac city built in

the United States in 1975 with 80,000 seats Silver dome. These large span building that the membrane structure has

the advantage of the large space is no longer a dark and oppressive, these domes can economically across large space.

Because the inflatable membrane to be overcome, such as recurrent structural failure occurs, continuous pneumatic

high costs, the complexity of the control air pressure space closure and other issues, people began to explore the

new form of the film structure. In North America, the film structure as a permanent building development of new

features. Such as the 1980 University of Florida Stephen C. 0 Connel Center, 1984 Lindsay Park Sports Center, 1989

San Diego liberation Center, 1990 Chene Park amphitheater are the perfect shape and innovative combination of

structure.

The late 1980s, Americans B. Fuller proposed the idea of ​​a tensegrity dome and the earliest introduction of this new

structure to cover a large space, people began to use this the cable - rod combinations film structure instead of

early inflatable dome. 1986 National Sports Center in San Olympic Gymnastics Hall and Fencing Hall designed by

Geiger. 1988 Weidlinger designed Ilinois State University Redbird Arena, the Thunder Dome in 1989, the Georgia Dome

in 1992, these buildings are used tensegrity structure system.

1980s, many famous architects began designing membrane structures in European countries and improved design

standards, its project is unique, more unique. The 1985 Schlumberger was the first European research center has a

membrane structure, cable - composite structure of the film. Across traditional roof of the auditorium, football

field tends to darken the space below the membrane structure built in Europe was not the case. The 1990 Rome Olympic

Stadium membrane structure hanging down from space compression ring frame is both lightweight and aesthetically

pleasing, become the most commonly used model across the auditorium roof, made more reasonable and economy than any

other structure.

Today, membrane structure has begun to spread throughout the world. Japan and South Korea co-hosted the 2002 World

Cup stadiums in Japan arena 10 stadium six membrane structure (Niigata Stadium, Kashima Stadium), Korea stadium 10

Stadium 5 using membrane structure (Seoul Stadium, Daegu Stadium), Saudi Arabia, JiDa Airport departure lounge

suspended membrane structure covers an area of ​​420,000 m2, is still the world's largest membrane structure building.

From the practical experience of domestic and foreign film structure has a strong vitality, has become a major

program of structural design selection.

The development of the membrane structure material

Europe and the United States, the film structure of the Early Japanese PVC coated polyester fiber membrane, the

membrane material having a higher strength, tear resistance is better able to meet the needs of the early membrane

structure the existence of the self-cleaning properties, but the material , impatience ultraviolet, short life, as

well as adverse climatic conditions may exist accident. Later, large span the membrane structure building, high

strength, good performance PTFE-coated glass fiber membrane since the knot has been more widely used. The 1990s, R &

D success PVF and PVDF membrane structure, and has been applied in the project.

Famous producers of the film structure is mainly concentrated in a few developed countries in the United States,

Japan and Germany. PVC film, and PVF film, the PVDF membrane mainly by France (Ferrari company), Germany (Mehler

(meters music) company, Durakin Company) (Seamen company) and South Korea (show Bo company) production; PTFE membrane

mainly by Japan Sun Industries strain type clubs, Asahi Glass Co., Ltd., Japan, and other production; addition, ETFE

film production only Japan's Asahi Glass Co., Ltd. and other three companies, due to the expensive, high construction

requirements only for specific sports venue construction.

Domestic film structural materials industry development status

The development of the domestic architecture of membrane structure

Membrane Structure in China relatively late development, starting in 1995, only the construction of a 3300m2 area of

​​the membrane structure, 1997 years ago, there were only a small number of small and medium-sized membrane structure

building; 8th National Games held in Shanghai in 1997, its main stadium grandstand cantilevered roofs membrane

structure canopy roof area of ​​36,000 m2, can accommodate 80,000 spectators. This is China's first large stadium roof

membrane structure, membrane structure opened a new chapter for our country, has a significant impact on the

development of the membrane structure. The Shanghai Stadium adopt fiberglass PTFE membrane material, all of the

Department of the imported products.

Membrane structures built within five years from 1997 to 2001, 37 million tons; membrane structure built in 2003 is

about 18 million tons; membrane structure built in 2005, in 2006 more than 33 and 40 million tons respectively.

Predict the membrane structure of our country will continue to grow at a speed of 15 to 20% per year, and will reach

60 million tons in 2010. With the growth of China's economic and cultural life of the rich, and more will be built

with novel functions, various forms of construction. World Expo 2010 will be held in Shanghai, the construction of

various types of exhibition hall and around the country vary in size membrane structure must be with the development

of the membrane structure technology, applications and more widely. Architectural membrane material has strong

vitality, is bound to be the mainstream in the development of 21st century architectural structure will be very broad

market prospects.

The development of the domestic film structural materials

Since the 1995 film structural materials applications in the domestic, high performance membrane materials mainly

rely on imports. The same time, China's enterprises, universities and other efforts to conduct the study of membrane

structure material substrate, coating processing technology, coatings and application performance, through the

introduction of technology and equipment, some Chinese enterprises have been able to produce PVC membranes, PVDF

membranes and PTFE membrane material. Ningbo Group Tianta, first developed PTFE fiberglass membrane material, 3m

glass fiber used 6m glass fiber used than foreign crude, large differences compared to the final product performance

and abroad; 2002 Shanghai Shen Dakota Bao Co., Ltd. is a full set of the introduction of the German company Mehler

(Miller) PVC + full set of hot melt PVDF adhesive film technology and German the KKA company's production lines and

equipment production PVDF membrane structural materials, the structural material of the membrane structure diagram

shown in Figure 6.

Figure 6 Shenzhen Middle School the stadium bleachers film structure

However, the domestic film structural materials due to the physical properties of poor or inadequate mechanical

properties, it remains difficult to meet the needs of the domestic large-scale engineering and industrial development

of membrane structure. Currently, 90% of the domestic film structural engineering materials imported film, such as

the 2008 Olympic Games in Beijing National Stadium - Bird's Nest, the National Aquatics Center - Water Cube all high

-performance membranes Germany FORTEX company and Japan's Asahi Glass Co., Ltd., the only two venues reached 320,000

m2 of membrane structure material.

The application prospects of the membrane structure material

The membrane structure is the latest development in a form that in the construction of the structure, to the

excellent performance of the fabric as the substrate, the use of a flexible cable or a rigid support structure to the

surface tension, thereby forming with a certain stiffness, capable of covering the structural system of the large

span space . The most important feature of the membrane is high strength, durability, fire flame retardant, self-

cleaning from ultraviolet rays affect the life of 15 to 25 years, with high transmittance, 73% of the heat

reflectivity, heat absorption small Bird's Nest steel structure engineering welding stress and strain control

techniques

I. Project Overview

National Stadium grandstand concrete frame structure with radial surround them and form the main roof space steel

structure completely separated. Space steel structure surrounded by 24-bay door truss within the stadium bowl

bleachers rotate made 22 bay through basic through. Structural components to support each other to form a mesh-like

architecture, composed Stadium "Bird's Nest" shape overall. All steel components form a structural and architectural

features.

Engineering ± 0.000 elevation relative to the absolute elevation 43.500m, saddle-shaped steel structure roof was

hyperboloid, north-south structural height of 40.746m EW structural height of 67.122m. The roof of the main structure

are box section chord section for basic l000mm x l000mm, lower chord section 800mm x800mm basic abdominal cross-

section of the rod is 600mm x 600mm, basic, intersecting webs with upper and lower chords, the roof rise 12.000m.

Vertical portfolio by 24 steel column supported by two 1200mm × 1200mm Box Column and a diamond-shaped steel

columns, each combination of steel column loads through it passed to the foundation. The basic structure cross-

section of the facade times 1200mm × l000mm, the top surface times structure cross-section is basic l000mm ×

l000mm.


1 steel structure design weight

Main truss: l2720 tons of composite columns: the structure of the 12,548 tons times: 11,670 tons
Stairs: 4137 tons bridleways: 800 tons Total: 41,875 tons

2 steel models thickness

The maximum thickness of the steel sheet lOOmm. When the plate thickness ≤ 34mm Q345 steel: when the plate thickness

≥ 36mm using Q345G daub material: a small amount of thick steel plate Q460, 8480ML steel. Local steel castings.

Thickness distribution:

- The combination steel columns in addition to a small amount of prism bottom of the column and the top is 90. lOOmm,

the rest is 50480mm, the vast majority of the other two square oblique column plate thickness for 30, 25, 20 mm.
- The truss chord individual segment 50mm, the rest are less than 40mm, most of them for 30, 25, 20 mm.
- The individual segments of the truss bottom chord 50,42 mm, the vast majority of 20mm.
The the - webs 20,14 lOmm majority of lOmm.
- Sub-structure of the plate thickness 36mm, the vast majority of less than 20mm.

3 steel performance


1 large size of the project, re-member tonnage

- Saddle-shaped steel roof long axis of approximately 333m, short axis approximately 280m: inner ring long axis the

approximately l82m, short axis approximately l24m: vector high 12m.
- The maximum weight of the composite steel column weighs about 520t per meter heaviest about lOt: main truss per

meter weighs about 3t.

2-node complex

- The main structure are large cross-section and the box member nodes in space listing the root of rod: time

structure node complex and changeable, less regularity.


Third, the construction program profiles

According to the adjusted preliminary design drawings and other technical conditions. Determine the final

installation program for the ground assembled altitude bulk construction method, T8-roots support system that is

arranged at the venue, the main structure of the slice or ground block assembly after forming, 800T and 600T crane

hoisted to the top of the temporary support, was divided into four districts J stages symmetry finished loading and

welding, after the completion of the structure and sub-structure of the facade of the main structure the T8

supporting system overall synchronization uninstall the final installation of the structure of the plane times.

Lamellar tearing problem analysis

Lamellar tearing risk analysis


Due to the formation of the welded joint is binding on the plate thickness direction, there is a certain tendency to

from the joints ways perspective, according lamellar tearing empirical formula:

LTR = INF (A) INF (B) INF (C) INF (D) INF (E):
INF (A) of the impact of the size of fillet S s larger value, LTR bigger. It should not be the large size of fillet.
INF (B) joints to form the way.
INF (C) to withstand the lateral restraint thickness Sa the influence of jLTR,; the greater, LTR the greater.
INF (D) is the binding degree of impact, restraint intensity R Yue, lamellar tearing the greater the tendency.
The INF (E) for the preheating conditions, using preheated advantageously.

According to the LTR of the calculated value know, the thickness greater than 40mm lamellar tearing great danger, but

produce lamellar tearing is mainly depending on the material of the steel, steel works optional its performance must

be meet the requirements of Zl5 ~ Z35, effectively prevent the emergence of lamellar tearing phenomenon in the

control of the stress-strain.

Five steel welding deformation and residual stress analysis and countermeasures

Welding deformation and residual stress is a major issue that must be taken seriously in steel construction, there

must be strict technical rules and countermeasures must be scientific and rational management, in the conduct of the

process of the project, so as to form a complete system management engineering, ensure the quality of the steel

structure engineering.

The basis of a welding deformation and residual stress analysis

The National Stadium steel structure engineering field welds divided into two main types: fillet weld and butt weld.

Generally fillet welding deformation is not too large, the residual energy is mainly present in the form of welding

residual stress of the steel structure of the weld and H ^ z: fillet weld is not a major force weld control of

welding The key to the size of the residual stress is the minimum size of fillet weld. The residual energy of the

thick plate butt weld shrinkage deformation of the weld and form of welding residual stress in the weld and H ^ z:

control of welding deformation and welding residual stress must be integrated governance. Practice has proved that:

welding stress and residual stress exist among the same weldment, both complementary and can be interchangeable, the

theoretical basis of the conclusions of the conservation of energy, see equation (1), (2).

Set the total weld energy E = 1:amounts. This unique structure has unlimited potential, able to adapt to a variety of

functions, and has strong vitality, will become the mainstream of the development of 21st century architectural

structure. (End)