Concrete column and steel beam constraint release the source of the problem

For concrete column and steel beam constraint release, mainly to have two kind of situations, one is turning two is released, rotate + translation release; in 3D3S want to achieve these two goals can be in a variety of ways.

1, rotation release, is the release of connections of the moment, can end of the beam is around a 3 axis of rotation release, can also be a column around the 3 axis of rotation release, can also be a Liang Genzhu top around the 3 axis of rotation release, the calculation result is the same, to get the correct result is the premise of Liang Genzhu's orientation to the right so, 3D3S, display the command you to be familiar with, often with.

2, rotation + translation release, is released at the junction of the moment, also the release of joint movement in one direction.To achieve this purpose, can be a beam around a 3 axis rotation release + beam along a 1 axis translational release, attention, beam 1 axis is the beam along the axial direction; also can be a string around a 3 axis rotation release + columns along the 2 axis translational release; it can also be a Liang Hezhu were done, the result is the same as the.

As for when there is a need for increased translational release, depends on the specific structure, energy conservation, translational release [force (mainly for the horizontal force) direction displacement release] will inevitably lead to the release, necessarily leads to the Liang Kuazhong deflection increases, the two are related; in general, the slope is greater, the horizontal force large deflection, smaller, and vice versa, the horizontal force is released, to see whether lower structure can bear, not just for translational release, need comprehensive consideration, release effects on the beams and release on the effect of column.According to my personal view, multiple span structure release, multi span can do continuous span, can reduce the deflection of the beam; single span structure can not release will not release, great influence on deflection.

In the 3D3S component of 123 shafts, many just school friends often confused, actually not difficult, the key is to master its characteristics, 1 shaft is a component along the axial direction, is subjected to axial force direction, 2 axis, the I-shaped cross section, is the web toward the direction, only need to remember this, 2 axis is the direction of web, two, 3D3S and K node direction, but also the direction of the 2 axis, for variable cross section member, K node direction also represents member web slope changes direction, such as variable cross section beam, the upper flange flat, the lower flange is variable, that is to say the web variable slope direction is down, so the K node direction should be the coordinates of Z axis in the negative direction, in the 3D3S is the K node in Z direction negative infinity is infinite, as to why this view, here can do not need to care about it.

3 axis is vertical web toward the direction, to decide the 2 axis, and then based on 2 axis determining 3 axis, on a number of rectangular cross section, defined in section time, we should pay attention to procedure provides the diagrams in the direction of a 23 axis, generally rectangular cross section need to display section to match the judgment, or define an H-shaped cross section, and then modify the section of rectangular cross section.

laser weldingBrazinghigh-frequency welding

2)
    The laser welding is the use of high-power coherent monochromatic sub streams to the laser beam focus from the welding heat source. This welding method usually continuous power laser welding and pulsed power laser welding. The advantages of laser welding need not be carried out in vacuum, the disadvantage is the Penetration than electron beam welding. Laser welding energy can perform precise control, and thus can achieve precision microdevices welding. It can be applied to many metals, in particular, is able to solve a number of difficult to weld metal and the welding of dissimilar metals.
       4.
    Brazing energy may be a chemical heat of reaction, may be an indirect heat energy. It is the use of a melting point than the metal having a low melting point of the brazing material for brazing, brazing materials and rely on capillary action into the gap of the joint contact surface, wetting the surface of the welded metal is heated so that the solder melts, the liquid phase and interdiffusion between solid phase and form a brazed joint. Therefore, brazing is a solid phase and a liquid phase of welding methods. Brazing heating temperature is lower, the base material does not melt, but also do not need to apply pressure. But before welding must take certain measures to clear the the welders surface oil, dirt, oxide film. This is an important guarantee for the workpiece wettability, to ensure the quality of the joint. Solder liquidus line humidity is higher than 450 ° C but below the melting point of the base metal material, referred to as brazing; below 450 ℃, referred to as soldering. Different brazing can be divided according to the heat source or heating methods: flame brazing, induction brazing, furnace brazing, dip brazing, resistance brazing or the like. Brazing, when the heating temperature is relatively low, so the impact on the performance of the workpiece material, the stress distortion of the weldment is also smaller. However, the strength of the brazed joints generally low heat capacity. Brazing can be used for welding carbon steel, stainless steel, superalloy, metallic material such as aluminum, copper, can also be connected to a dissimilar metal, metal and nonmetal. Suitable for welding by not upload or room temperature connector is particularly suitable for precision miniature and complex multi-brazing seam weldment.
       5. Other welding methods
    These welding methods belonging to the different degrees of specialized welding method, a narrow its scope. Main the electroslag welding resistance heat energy, high-frequency welding; chemical energy for the welding gas welding, pressure welding, explosion welding; machinery for welding energy friction welding, cold welding, ultrasonic welding, diffusion welding.
Electroslag welding (1)
    As previously described, the slag resistance of the electroslag welding is a welding method of the heat energy. Welding process in the vertical welding position, the assembly gap formed by the the two workpiece face and both sides of the water-cooled copper slider. The welding current through the slag generated heat of the resistance of the workpiece ends melted. According to the shape of the electrode used in the welding, electroslag welding into silk electroslag welding, plate electroslag welding and melting mouth electroslag welding. The electroslag welding advantage of: welding workpiece thickness is greater than (from 30mm to 1000mm), and high productivity. Mainly used in the welding section butt joints and T-joints. The electroslag welding can be used for various steel welding, assembly welding can be used for casting. Electroslag welding head are slower due to heating and cooling, heat affected zone width, coarse microstructure and toughness, are generally required to normalizing after welding.
(2)
    The same frequency welding is solid resistance heat energy. Resistor thermal welding, using high-frequency current is generated in the workpiece so that the surface of the workpiece weld zone is heated to the melting or close to the plastic state, then applied (or not applied) upsetting force to achieve the binding of the metal. So it is a solid phase a resistance welding method. High frequency welding according to the high-frequency current to generate heat in the workpiece can be divided into contact with high-frequency welding and induction of high-frequency welding. Contacting the high-frequency welding, a high frequency current through the contact with the workpiece mechanical incoming workpiece. The induction of high-frequency welding, high frequency current through the workpiece the coupling effect of the external induction coil within the workpiece generates an induced current. High-frequency welding is a a strong specialized welding method, according to the product is equipped with special equipment. High productivity welding speed of up to 30m/min. Mainly used for the manufacture of pipes welded longitudinal seam or spiral seam.
(3) welding
    Welding with a gas flame of a welding method as a heat source. The most widely used in acetylene gas as fuel oxygen - acetylene flame. Easy to operate simple equipment but gas welding heating rate and low productivity, the heat affected zone and prone to large deformation. Gas welding can be used for welding of ferrous metals, non-ferrous metals and alloys. Generally applicable to repair and a single piece of sheet metal welding.
(4) pressure welding
    Pressure welding and gas welding, pressure welding gas flame as a heat source. Welding the two butt end portion of the workpiece is heated to a certain temperature, then applying sufficient pressure to obtain a firm joint. Is a solid phase welding. Pressure welding without filler metal, commonly used in the rails welded and welded steel.
(5) explosion welding
    Explosive welding is a chemical reaction heat energy of another solid phase welding method. But it is the use of the energy generated by the explosives to achieve a metal connection. Two metal within less than a second explosion waves can be accelerated impact the formation of the metal binding. The most widely in a variety of welding methods, the combined range of the explosive welding of dissimilar metals can be welded. Two metal welding metallurgy incompatible with explosion welding various transition joints. The explosion welding is used for the large surface area of ​​the tablet coated with an efficient method of manufacturing composite panels.
(6) friction welding
    Friction welding is the mechanical energy is the energy of the solid-phase welding. It is the use of the heat generated by mechanical friction between the two surfaces to achieve the connection of the metal. Friction welding heat is concentrated at the joining surfaces, and therefore the narrow heat-affected zone. Required to exert pressure between the two surfaces, and in most cases is increased when heat termination pressure, so that the hot metal by the upsetting is incorporated, generally combined with the surface is not melted. Friction welding productivity is high, almost all friction welding forging of the metal can in principle. Friction welding can also be used for the welding of dissimilar metals. To apply to the cross section is circular the maximum diameter of a workpiece of 100mm.
(7) The ultrasonic welding
    Ultrasonic welding is also a mechanical energy to the energy of the solid-phase welding method. For ultrasonic welding, the workpiece under the low static pressure, high frequency vibrations emitted by the acoustic pole enables joints generate strong crack friction and heated to the soldering temperature and form a combination. The ultrasonic welding can be used for the welding between the the most of the metal material, to achieve the welding between the metal, dissimilar metals and metal and nonmetal. Applied to the metal wire, or foil, or less than 2 ~ 3mm sheet metal joint repetitive.
(8) diffusion bonding
    Diffusion welding generally based on indirect heat energy solid-phase welding method. Is usually carried out in vacuum or under a protective atmosphere. Welding when the two welders member surface contact under high temperatures and large pressure and incubated for a certain time, to reach the distance between atoms, After atoms simplicity mutual diffusion bonded. Not only need to be cleaned before welding the workpiece surface oxides and other impurities, and surface roughness below a certain value in order to ensure the welding quality. Diffusion welding of welding material performance almost no harmful effects. It is a lot of the same species, and the dissimilar metal, as well as some non-metallic materials, such as ceramics, etc. can be soldered. Diffusion bonding can be the welding complex structure and thickness of very different workpiece.
       The welding process: → arc welding (TIG, manual arc welding, submerged arc welding, gas tungsten-shielded arc welding, and other high-energy beam welding (electron beam welding, plasma arc welding, gas metal arc welding) → resistance welding → laser welding) → brazing → the resistance heat energy: electroslag welding, high frequency welding; → chemical welding energy: gas welding, pressure welding, explosion welding; → machinery for welding energy: friction welding, cold welding ultrasonic welding, diffusion welding
Welding process accuracy deformation heat affected weld quality solder conditions of use
Laser welded precision small small good
 Brazing precision general general general needs of the overall heating
Generally no need electrode resistance welding precision greatly
TIG generally greatly generally need to need to electrode
Plasma welding is better in general general general need to need to electrode
Electron beam welding precision little good vacuum

he development of light steel

Since the 1990s, the development of China's steel building very quickly, and some representatives of the city's

iconic high-rise buildings built for the steel structure has opened a new chapter in the development of our country.

As the world's third-highest 88 floors, high 420m Jinmao Tower has been completed and is now operational. Allegedly

the world's first highly Pudong, Shanghai World Financial Center, 460m, 95 floors, the building area of ​​310,000 m2,

is now stepping up its construction. By foreign investment in Dalian, President Building, is stepping up its

preparation, a total of 95 floors, allegedly after the completion of its height will be among the highest in the

world.

The development of light steel structure is more is in full swing, especially in the construction of industrial

plants is more rapid. Substantial growth in the number of firms from steel manufacturing and construction can get a

glimpse, such as the Shanghai steel manufacturing and construction unit has increased from dozens to more than 400

development, only Shanghai Baosteel region there are nearly a hundred The home of the steel structure factory.

Excellent situation, how to capitalize on the trend, do a good job of design and construction quality, which is a

very urgent problem.


Light steel structure and its Scope

The so-called light steel structure constituted by the following steel: cold-formed steel structures; hot-rolled

light steel structure; welding or high frequency welding of light steel structure; lightweight steel tube structure;

siding thin welded combination of beams and welding structure constituted by a combination of column.


1. Scope

According to our current situation, this structure because of its expense obvious advantages, have been widely used

in the single-storey industrial plant a multilayered industrial plants, office buildings and high-rise buildings in

non-load-bearing components such as. Storey industrial factory, usually the main H-shaped steel, welded connection as

beams and columns, a C-shaped or Z-shaped light steel purlins, roof or floor system with pressure-type color steel

plate as the surface layer, the above concrete, steel sheeting can be used as reinforced, if necessary, can also be

matched with reinforced. Wall cladding can be applied to single-layer or sandwich inside the pressure plate, sandwich

plate can be filled with a variety of insulation layer.

2 main advantages

(1) The construction period is short: light steel biggest advantage is that all of the components can be produced by

a factory field splices installed in just 45 days to two months, generally smaller industrial plants, and the use of

reinforced concrete buildings will have to about 8 to 12 months.

(2) comprehensive economic benefit: due to the short construction period, can be put to use in advance, to obtain

investment returns in advance; using colorful color steel sheeting, beautiful, gorgeous, dynamic sense to improve the

surrounding environment; buildings light weight, under normal circumstances, do not need to do pile foundation, you

can save the investment; due polyphenylene hexene foam sandwich board or veneer plus cotton insulation measures,

insulation, thermal insulation, and every chapter to good effect. Color steel galvanized substrate surface with

silicone as processed by the two in addition to two bake better durability, cost has been lower than the current

market price, light steel reinforced concrete structure, when greater the span of the plant, its advantage is more

obvious, which is on which it is a big advantage in the competition.


(3) seismic performance: steel structure is a flexible structure, light weight, and thus can effectively reduce the

seismic response and disaster impact, highly conducive to the earthquake. China is a multi-the earthquake zone

countries, should be a lot to promote the use of steel structures, can greatly reduce the earthquake disaster, and

casualties in the earthquake zone construction. At present, Tianjin has officially launched the light steel structure

house.

(4) is appropriate demolition relocation: Once the owners had made site are not satisfied or unexpected changes in

the external environment, the entire building in a very short time the demolition, the loss is minimal, and all of

these reinforced concrete building with .

It is because of the many advantages of light steel, and with the recent fire safety, the continuous emergence of new

anti-corrosion products have to solve the shortcomings of poor light steel corrosion resistance makes it gained in

industrial plants as well as civilian facilities a wide range of applications.

Considerations in the choice of materials and design

Light steel structure as ordinary steel structure derivative structure, the basic computing theory and the latter is

basically the same. Details can be found in Shanghai standard DBJ08-68-97 "light steel design procedures and the

China Engineering Construction Standardization Association standard CECS102: 98" portal frame houses light steel

structure technical regulations, only emphasized several points:

Timber priority should be given to the "H"-shaped steel, it is subject to reasonable force, stitching, easy

processing. Q235 steel and low alloy steel of 16Mn, 15MnV or 15MnV steel load-bearing structure is appropriate, but

should pay attention to the Q235-A carbon content of the steel as the delivery conditions, weldability is no

assurance that it should not be used as a welded structure. For plate thickness greater than 25 mm beam flange

column, field welding of the beam-column joints should not be with Q235-BF, should try to use the Q235-B or Q235-Bb,

Q235-C should be chosen for a particularly important structure or Q235-D.

Steel structure stability problem of the reliability of the Research Review

(A) The steel structure system stability Research
The past two to three decades, the use of high-strength steel, the development of construction technology and computer applications make the steel system development and wide range of applications possible. The steel system stability has been the research areas of concern to scholars at home and abroad. After decades of research, has made a lot of research.
So far, the study of the basic building blocks of steel structure theory more and more mature stability analysis based on a variety of numerical analysis [1]. Member overall stability and local stability of the interaction of theory and design applications has yet to be carried out in-depth research. Reticulated shells damage due to structural instability, reticulated shell stability is a very important issue, correct latticed shell structure the monolayer shells structure stability analysis and design is to ensure that network shell the security of the key. Since the sixties, the the reticulated shell nonlinear stability analysis has been the focus of attention of scholars at home and abroad. Britain, the United States, Germany, Italy, Australia, Romania, Poland and other countries, researchers conducted a wide range of theoretical analysis and study of the theoretical aspects.Various methods such as the Newton - Raphson iteration method and arc-length method, generalized inverse method, artificial spring method, automatic solution technology, energy balancing technology to track the yield problem the whole process, the structure of the descent stage curves become possible [2] . Domestic scholars have undertaken extensive research about the stability of reticulated shells. [3] on the basis of the foreign research, through accurate theories expression, reasonable path to balance tracking technology and iterative strategies geometric nonlinear analysis of complex structural systems and regularity results. Random defect mode method and consistent defects modal method while taking advantage of the two methods, the reticulated shell structures of various initial defect study to describe the actual structure carrying. Some scholars to conduct experimental research [4] - [6], the validity and accuracy of different analytical methods were described. [7] the power of reticulated shell instability mechanism, stability criteria, dynamic postbuckling research. Like dynamic stability study of of reticulated shells sensitive structures such defects in the role of the strong winds and earthquakes, as it involves the theory of stability and vibration theory, it is difficult, the research is still very limited. [8] studied the dynamic stability of the spatial structure.
Large span truss arch structure as a new large-span structure, its stability, very little research. [9] using nonlinear finite element theory to the entire process of tracking the stability of large-span truss arch structure, and to draw some conclusions with practical application value. The cable-stayed space grid structure is a new type of hybrid space structure, the depth and breadth of its research is still very limited. [10] pointed out the need to further study the stability of the cable-stayed monolayer shells. Studies have grid structure the pillars supporting role and the grid structure of the cable-stayed plane in the grid structure constraints simplify the equivalent spring pillar stability, draw some useful conclusions 11]. Pre-tensioning structural system is currently more and more, a new type of structural system [12] - [16]. The system theoretical studies of this system largely lags behind the actual application, in particular, the study did not pay sufficient attention to the pre-tensioning structural system stability, the research is still very limited. [12] [13], the stability of the initial equilibrium state of the pre-tensioning structural system must attract enough attention, instability and failure may also occur under load prestressed cable structure system in working condition, and the actual The design calculations proposed two methods - direct algorithm with stability design method, nature and structural stability of the structure of the system to determine the method, and provide some theoretical guidance for further research.
In addition, scholars from the perspective of the overall stability of the stability of the steel frame structure, draw some useful conclusions [17] - [19].
(B) of the steel structure system stability study
Steel structure system stability studies made some progress, but there are also some problems can not be ignored:
1) the study of the stability of reticulated shells, beam - column element theory has become a major research tool. Beam - column element if true reflection of the stress state of the structure of the network shell is hard to say, although some scholars have been fixed beam - column unit [3]. The main problem is how to reflect the coupled effect of axial forces and bending moments.
2) the overall stability in the large span structure design, with locally stable relationship is a question worth exploring, take a unified stability safety factor in the design of large-span structures do not reflect the overall stability and local stability associated.
3) pre-tensioning structural system stable design theory is far from perfect, yet do not have a complete theoretical system to analyze the stability of the pre-tensioning structural system.
4) Study on the stability of the steel structure system, there are many random factors, the the structure random effects most of the analysis process is limited to determining the structure parameters, random load input range of such a pattern, and in the actual project, due to structural parameters uncertainty will cause the structural response of a significant difference. So we should focus on considering the structure of the random parameters extremum instability, interference-type buckling jumping instability problem in [20] [21] had to consider the stability problem of the random parameters dome network shell beneficial.
Steel structure system reliability stability problems
The actual structure due to the presence of a variety of random defects ideal structural differences. For the sensitivity of the structure of the defect, the defect may cause a sharp decline in the structural stability, it is necessary to consider the impact of random parameters, the introduction of the reliability of analytical methods, stability reliability.Due to the large-span steel structure system reliability study involved more knowledge of mechanics and mathematics, there is a certain degree of difficulty, the limited success of current research in this area. [2] had the reliability of the analysis and design of the stability of reticulated shell exhaustive research, rich theoretical and computational methods of structural reliability, and applied to engineering analysis and design of the structure, showing good prospects.
The uncertainties sources of structural analysis of (a)
Affect just many of the basic variables of the structural stability of the system uncertainty is random, and is generally divided into three categories:
1) physical, geometrical uncertainty: such as material (elastic modulus, yield stress, Poisson's ratio, etc.), the size of the rod member, the cross-sectional area, the residual stress, initial deformation.
2) the statistical uncertainty: Statistics and relating to the stability of the physical quantities and Geometrical always based on limited samples to select the probability density function, so bring some empirical. This uncertainty called statistical uncertainty is caused by the lack of information.
3) the uncertainty of the model: In order to analyze the structure, the various factors mentioned assumptions, mathematical models, boundary conditions and the current level of technology is difficult to reflect in the calculation, the result of the theoretical values ​​with the actual carrying capacity differences attributed to the uncertainty of the model.
(B) the reliability of the study of the structure
Scholars of structural reliability theory has a more in-depth study, reliability analysis of the reliability calculation method and the complex structure made a lot of research [22] - [39].
The ultimate goal of any engineering analysis and design is to design structures to meet the different requirements of different features - security, usability, durability, due to the presence of uncertainty, you need these uncertainties added engineering design, whicha lot of reliability methods. In order to estimate the structural reliability, we must first solve the load and resistance parameters as well as the functional relationship between them, where this relationship (also called functions) denoted X1, X2, ..., Xn is a random variable. Limit state (or failure surface) is defined as Z0, reliability parameters describe the reliability index is defined as the minimum distance of the coordinate origin to the failure surface is calculated for reliability indicators are generally two methods: a reliability method (FORM ) and secondary Reliability of methods (SORM).
(C) Review of numerical methods of analysis for structural reliability
Performance function g (x) usually can not articulate the complex structure, usually by numerical methods (such as finite element) to calculate the response function, the structure of the input random variables. These numerical methods are generally divided into three categories: (1) Monte Carlo simulation (MonteCarloSimulation) [34] (including efficient sampling and variance reduction techniques); (2) in response to surface method (ResponseSurfaceMethod) [31] [32] ) based on the sensitivity analysis method (Sensitivity-basedApproach) [30].
1) Monte Carlo simulation (MonteCarloSimulation)
The basic idea of ​​the Monte Carlo simulation method for statistical analysis to calculate the reliability of the structure during every uncertainty analysis before randomly generated a set of input variables, a large number of repeat uncertainty analysis of structural response output parameter. Combine Monte Carlo simulation with finite element method, finite element method in Monte Carlo. Monte Carlo finite element method is usually calculated as the reliability of the relative exact solution, but to achieve high accuracy, a sufficient number of samples must be taken, the computational workload is quite vast.
2) Response surface methodology (ResponseSurfaceMethod)
The basic idea of ​​the response surface method implicit performance function g (X) (one or quadratic polynomial) is expressed by a polynomial approximation to construct a clear expression of the form, where X contains all load and resistance random variables a vector. In essence, the response surface method is a statistical method, considered this way to find the input variable values ​​variability or uncertainty after the response best value. The probability of failure by once or twice a reliability method. Response surface method for a problem with a large number of random variables, accurately construct an approximate polynomial deterministic analysis required is quite huge, so this method is very time-consuming. Even for a problem with a small number of random variables, response surface method of reliability estimation accuracy with the accuracy of the approximate polynomial functions. If implicit functions has strong nonlinear function approximation is very approximate reliability estimate is very approximate.
3) based on the sensitivity of the analytical method (Sensitivity-basedApproach)
Based on sensitivity analysis and a reliability method (FORM) / secondary reliability method (SORM) combined analysis of the reliability problems with implicit functions overcome the Monte Carlo simulation and response surface method shortcomings. This method in the process of looking for control point (also called a minimum distance point), the true value and the real gradient of the function of the information used in each iteration are functional, and using optimization method converges to the minimum distance point of the control point, with the Monte compared Carlo simulation and the response surface method, it is time-consuming small than the response surface method more accurately. In addition, based on the sensitivity analysis methods from the design point of view to know the sensitivity of the structural response of the basic random variables. Which may be based on the uncertainty of the random variable and their structural characteristics different design safety factor of different random variables. The method can also be based on the sensitivity analysis does not affect the calculation accuracy, ignore those little random variables on structural reliability, thereby saving computation time. Based on the sensitivity analysis method using an iterative the perturbation analysis technology have combined to produce a so-called stochastic finite element method (StochasticFiniteElementMethod) and the finite element method.Iterative perturbation technique stochastic finite element method can be used to carry out non-linear analysis of the structure.
4) steel structure system stability reliability research methods
Just the reliability of the study of the structural system stability, the stochastic finite element method provides a powerful means of analysis, stochastic finite element method can be expected due to the stochastic finite element to consider the actual structure of the presence of a variety of random factors, so [ 30] in this field of research will have a good prospect.

Light steel building projects the quality investigation drip to

Light steel building means: portal frame light steel structure housing, pressure plate sandwich panel light envelope structure, 1 to 3 layers of light steel residential, low-rise office light steel structure buildings and light combination of housing, etc. which the widest range of portal frame light steel structure housing applications, the largest amount. This article surveys the main content is about the quality of the project portal frame light steel structure housing situation.
A portal frame light steel building development overview:
A review of twenty years history of the development of steel buildings, light steel structure housing the main portal frame is one of the fastest growing and most widely used building new technologies and products.
Entry of foreign manufacturers, the introduction of new technologies and new products:
1) 1979 Shanghai Fisheries Road Lun library to introduce Japanese S60 pressure plate molding machine for plant Lun library roof, Shanghai Baosteel in 1980 a project to introduce Japan W550, V115N steel sheeting forming machine roof wall in a project surface nearly 600,000 square meters of building envelope applications, it is the first time in the early 1980s, the largest amount of engineering.
2) 1983 Economic Development Zone, Shekou Industrial Zone began deep training and the introduction of a large number of the United Kingdom, the United States, Australia and Japan, the door-frame light steel structure workshop Lun library. Introduction of Australia prestressed door lattice-type light steel structure Lun library. Coastal economic development zone then gradually introduce abroad light steel plant Lun library, this building can also be used for logistics Lun Chu, supermarkets, wholesale markets, farmers markets and other commercial buildings; for sports and drinking places Museum and Exhibition Center; used in office buildings and other multi-storey buildings.
3) 1994 U.S. companies invest in creating Upbest Steel Structure Co., Ltd., and the Jiading plant put into operation in 1996. Has over 500 large and medium-sized projects in the domestic construction, building area of ​​more than 580 million square meters.
Engineering Construction Co., Ltd. of the United States the Midland Steel Structure Co., Ltd. (USA) and the United States Hongyu built in China in 1994 dozens of product design, manufacturing technology and management software, all imported from the United States of America USA steel building systems, providing customers with provide housing design, production to install the perfect service.
PCC Steel, Shanghai Baosteel Group Investment Holdings in 1993, the Taiwan management into shares of the steel building company. The Baocheng Steel set to introduce the American Maple design systems, building products, systems and production lines, with a set of pre-engineered steel housing sales offer design, installation in one full set of services.
ASTRON building system is the best quality of the Luxembourg subsidiary in the United States in Europe, the maximum amount of light steel structure building system. ASTRON building system in 1994, China has built more than a dozen large projects in Beijing, Suzhou and other places.
Taiwan-owned enterprise in 1994, Hua Yin factory in Xiamen, factories in Kunshan, Jiangsu Province in 1996, has set up branches and offices in Beijing, Shanghai, Dongguan, Xi'an, Nanjing and other places.
Then manufacturers entering the country, the United States Belem Steel Structure Construction Co., Ltd.; Oddo, Singapore, Malaysia and Australia joint investment company of steel products; many manufacturers of Taiwan-funded enterprises in Hangzhou Xinfeng Steel Company.
4) The key new materials, new products and new technology:
Computer-aided design and production of the portal frame (1) (CAD-CAM), portal frame light steel structure housing design and construction procedures.
(2) z-type oblique curling cold-formed steel, C-type cold-formed thin-walled of section steel Eurya bar wall beam material, design calculations and tectonic the knee bracing settings and structure;
(3) the steel sheeting of the roof and wall material selection, design calculations and links structure; the board upright seam 360 degrees occlusion pressure plate type connections and other accessories, board and other accessories of the the chimeric pressure plate connections sandwich panel board and component connections, the manufacturers own roofing systems, wall systems.
2. Domestic portal frame light steel structure housing development
1) 1980 Shanghai Baosteel Construction Headquarters was established thematic group pressed aluminum steel sheeting Experimental Study digestion and absorption of a project to introduce Japanese color coated steel sheeting and molding equipment, test use of domestic aluminum alloy plate instead of color coated layer steel plate made pressure plate for roof and wall building envelope, after an investigation and extensive experimental research in Baosteel roof and wall of a project to promote application of more than 60 million square meters of aluminum alloy pressure plate, pressure plate and molding research and application of the production line, and the National Science and Technology Progress Award.
2) in 1984, the Building Research Institute of the Ministry of Metallurgical Industry researchers in learning the Baosteel and Shenzhen Shekou Industrial Zone pressure plate and gantry frame light steel structure on the basis of foreign advanced technology, combined with the specific situation of China research and development of portal frame light Steel plant Lun library, first used in the Business Department of the urgent need to build national cotton reserve Lun She, three years in the areas of Shandong and Henan three provinces over forty, construction of a light steel cotton Lun library of more than 300 buildings, construction area of ​​more than 200,000 square meters, the project won the National Science and Technology Progress Award. 1986 bear food infrastructure of the Department of Commerce in Nagqu Prefecture in Tibet national food reserves Lun library construction, praise of the Tibet Autonomous Region and the Ministry of Commerce.
3) Building Research Institute of the Ministry of Metallurgical Industry is one of the earliest research and development of light steel structure housing units, a compound of a group of researchers lightweight welded H-shaped steel, cold-formed steel, the mechanical properties of the steel sheeting, processing technology and its processing equipment, other accessories fittings and sealing materials research and development, engineering design and application of light steel building, presided over or participated in the preparation of national standards and regulations and standards.
4) With the deepening of reform and opening up, China's rapid economic growth, the portal frame light steel structure housing industry has been rapid development, especially in the southeast coastal areas, new plants Lun library growth in demand prompted manufacturers of light steel structure housing processing installation mushroomed developed from the beginning of the development of small-scale modern enterprise Hangxiao Steel Seiko Zhejiang Hengda Steel, Shanghai GM, Wu Tai Steel, four new Steel, Baosteel color plates, northern space Steel enterprises are professional the Beijing Foton Steel, Beijing multidimensional Steel, Chengdu Huiyuan, Sichuan Hengsheng portal frame light steel structure manufacturer, annual sales are in the hundreds of millions, more than ten billion yuan. The national manufacturers engaged in the manufacture of light steel structure of the portal frame is estimated that about 500, more than 50 of a certain scale. Portal frame light steel structure fabrication and installation of quality housing also gradually improve, more and more beautiful novel architectural modeling, such as Cambridge and Pu Industrial Park of Shanghai GM plant, Butler contractor Motorola Tianjin, Shanghai and the United States built construction Tianjin Development Zone, the mint plant and a new machine tool plant in Beijing, Hunan six built construction Changsha Bosch plant and so are the industry quality engineering.
5) pressed steel sandwich panel processing manufacturers across the country, some manufacturers already own roof and wall containment system, some manufacturers to introduce advanced foreign equipment and technology has improved continuously. Dozens of domestic pressure plate board type, and most of its production lines are manufactured domestically. Introduction of sandwich panel production line manufacturers, according to incomplete statistics, there are more than 20 production lines, mainly imported from Italy, Germany, South Korea, Australia and other countries. At present, the domestic manufacturers can produce sandwich panel production line.
6) portal frame light steel structure housing a large number of applications, driven by the development and prosperity of the design software development of the related industries, the manufacturing of welded steel, cold-formed steel pressure plate processing equipment, lighting tile also many other accessories connected pieces and sealing materials manufacturer and agent technology level gradually improved.
7) on the design and construction standards and regulations and of the preparation of the Atlas:
(1) Ministry of Metallurgical Industry Standards pressed sheet metal design and construction procedures "YBJ216-88, the Metallurgy Building Research Institute of the Ministry of Industry editor, is now being revised.
(2) China Engineering Construction Standardization Association standard portal frame light housing steel structure technical regulations CECS102: 98, Steel Structure Committee of China Construction Metal Structure Association, China Building Standard Design & Research Institute editor. The 2002 revision of the gantry frame light house steel structure the technical regulations CECS102: 2002. The gantry frame light house steel components JG144-2002.
(3) the national standard of the People's Republic of China "cold-formed steel structure technical specifications" GB50018-2002 "Steel Structure Engineering Construction Quality Acceptance" GB50205 - 2002 has a rigid frame, Eurya bar and wall beams, steel sheeting special section.
(4) New standard atlas have: the gantry frame light house steel structure (no crane) "Atlas No. 02SG518-1 gantry frame light house steel structure (crane)," Atlas No. 04SG518- 3, the pressure plate, sandwich panel roof and wall building construction "01J925-1, 06J925-2.
In summary it can be seen, the portal frame light steel building is one of the most promising building structure type and products, according to the statistics, in 2004 the gantry frame light house and the color coating steel sheeting steel accounted for 35.8% of the total amount of steel in the steel building, its construction area accounts for more than 80% of the total area of ​​the steel building. 2006 the young steel structure manufacturers Butler sales of 17 billion yuan, the construction area of ​​3.8 million square meters; the northern space sales of 1.235 billion yuan, the construction area of ​​3.25 million square meters. The fittings manufacturers Zhe Jiang Zhencheng sales reached 400 million yuan, self-tapping screws to buy 3 billion. The gantry frame light house in all walks of various types of plant and warehouses, supermarkets and wholesale markets store buildings, office and school buildings, a small stadium training hall gym, exhibition halls displaying very wide range of applications.

Portal frame light steel building problems:
Portal frame light steel structure housing each year the number of millions of square meters of the increase, but should see us there are still many technical and managerial aspects of the design calculations, building construction, manufacture, installation quality and after-sales service issues, differences between enterprises is relatively large, the overall level of foreign advanced technology gap, the portal frame light steel structure housing project quality overall is good, but due to the fast development of the industry, some of the technical regulations and management measures not sound, light steel construction market is chaotic, weak individual manufacturers quality awareness, lack of responsibility, the long-term goal of quality first, safety in production only in slogans, chaotic management, illegal subcontracting layers of subcontractors to cut corners in order to the times charged lower prices, this vicious competition will inevitably lead to the decline in the quality of the project, seriously affecting the reputation and development of the industry.
1) quality problems reflected in the housing use functional defects: the main problems found in the portal frame light steel structure houses completed and put into use following the impact of these problems, large will discontinued. :
(1) Roof leaks: because most of the roof the double steel sheeting and insulation glass wool composite is not easy to find the exact point of leakage, often also drain repair. Roof slab the condensation dripping impact production.
(2) wall windows up and down the eaves, door, awning extended parts sealed well water;
(3) plant poor quality of the installation and stiffness pulled crane plant shaking, the some plant the card rails phenomenon crane start inflexible;
(4) plant by strong winds or typhoon toppled or partial damage to the plant was overwhelmed by the blizzard or partially damaged;
2) design management and design quality problems:
(1) has a light steel special design qualification, but the technology backbone in place or the technical level is not high, bear outside the the design qualification level design; lightweight steel special design qualification everywhere affiliated; strict plan approval requirements; industry professional and technical personnel to be trained to improve the overall level of light steel special design qualification should be strict examination and approval, to strengthen management. Steel manufacturers design their own construction but also to the strict quality management to prevent jerry-building design and construction.
(2) In order to meet the requirements of the low price of the contract, the technical staff in without trial research is based on case excessive "optimize" the amount of steel portal frame, roof slope more and more flat the the steel sheeting wave more election The smaller the plate thickness is thin, the result of doing the door-frame light steel building carrying capacity reserve further reduced, could not resist the attacks of the strong winds and heavy snow.
(3) did not consider the special strengthening measures designed and constructed for the windy and snowy regions.
(4) The manufacturers of light steel special design qualification training of designers is not enough, designers studying learning lack not reference standard atlas design, structural design and building construction are evident at the unreasonable.
3) Steel Components manufacture and installation of the problems:
(1) the material selection of steel and steel plate thickness and design do not conform, most choose low intensity thin plate.
(2) Production of portal frame beams and columns H beam flanges and webs of steel plate flatness, welding quality steel components rust paint quality problems.
(3) did not follow the formal portal frame installation sequence for installation between the pillars supporting the roof support and brace no tension exists in name only some 10,000 square meters on engineering during installation, blown down by strong winds, causing a great loss.
(4) lap steel sheeting for roofing, roof openings at through the ethos floor at the pressure plate and lighting tile lap joints, waterproof construction imperfect measures, the construction is not causing roof leakage risks carefully. Some project Roofing self-tapping screws leakage hit, the impact of wind resistance. In addition, the roof profiled wall plate other parts processing installation accuracy directly affect the building's facade and beautiful, should also be given attention.
(5) do not pay attention to the civil construction of steel structure members, color coated steel sheeting pollute.
(6) steel columns independent foundation to the buried anchor bolts position is not accurate enough, the the basic top elevation error a direct impact on the accuracy of the installation of the pillars.
4) construction supervision or quality supervision station technical staff of the steel structure are not familiar with, it is difficult to find problems to solve the problem.
5) the responsibility of the owners and the credibility problem: Some gantry frame light house steel quality problems and the owners, for example, at the tender stage, the owners only consider the price (according to the strength of the manufacturers of several investigations lowest low bid in the price of 245 yuan / square meter, the most Gao 850 yuan / square meters), the price is too low forcing manufacturers to cut corners, According to the survey results, the portal frame light plant profit margin is only about 4.2%, if the final payment is received not back manufacturers would lose money. Tender required schedule too tight caused whirl progress rush period, some process is skilled work can not be sloppy, for example, encountered the Roof Engineering crashing will cause water leakage hidden; addition, manufacturers generally reflect the owners can not comply with the contract scheduled to pay for projects, especially the final payment is difficult to discuss back, as of 2006 less the prop owed 600 million, more prop arrears amounted to 50 million yuan, the problem is too serious, I hope to attract the leading departments to attach importance given to solve, the owners also talk about integrity.

Light steel structure construction industry healthy development proposals:
1) Looking to the future light steel building is a most promising building structure type and products, excellent performance for the continued development of light steel structure industry lay the foundation. Twenty-five years, the portal frame light steel structure house from scratch, from small to large, from simple to Gao file, unprecedented speed of development, popularization applied to other structural type of difficulty the degree of confidence in all parts of the country, Many manufacturers with annual sales of more than a billion, several large annual sales of more than ten billion. The next ten years, China's economic sustainable development and the revitalization of northeast, central China, the development of the western region gave light steel industry business opportunities, light steel building industry promising.
2) technological innovation is driving the sustainable development of light steel construction industry.
Portal frame light steel structure housing each year the number of millions of square meters of the increase, but should see us there are still many technical and managerial aspects of the design calculations, building construction, manufacture, installation quality and after-sales service issues, differences between enterprises is relatively large, the overall level of foreign advanced technology gap, qualified enterprises should set up special funds, professional staff for research and development of new products and technology, brand-name industry, engage in their own brand products so as to improve the competitiveness of enterprises in the market. For example: how to improve the capacity of portal frame light steel structure housing the wind resistance, anti-blizzard, how rich houses architectural modeling, and the creation of a unique building system, computer-aided design and manufacturing (CAD - CAM) research and development, H side welding of steel flange and web technology research is good research topic.
3) the quality and integrity is the key to the healthy development of light steel construction industry.
Portal frame light steel structure housing project quality overall is good, but due to the fast development of the industry, a number of technical regulations and management measures are not perfect, light steel construction market is chaotic, individual manufacturers cut corners, shoddy down prices, this vicious competition will inevitably lead to the decline in the quality of the project, and seriously affect the credibility of the industry and development. In order to ensure the quality of the project, the enterprise should be strictly design and construction management to formulate concrete steel structure of the company process, installation method and quality testing methods, in accordance with current national and industry standards and regulations, to develop the processing of pressed steel sandwich panel installation guide to ensure that each project are qualified, excellent, and establish a good business reputation. The industry as a whole will be a healthy development.

4) It is recommended often organized industry, new technologies and new product seminars, design and construction of key projects and large-scale projects and technological exchanges, engineering, accident analysis, scientific enterprise management experience exchange activities; give full play to the advantages of university research, expert advice, organizational research on key projects, design construction of a joint technical research; practitioners and technical personnel conduct regular training and examination requirements of the certificates; establish a system of inspection for the annual light design and production of special steel company owned post, strict management and inspection; carry light steel structure manufacturers with foreign technology engage in innovation cooperation and exchanges, broadens the mind. These measures will improve the technical level of the industry as a whole.
5) Experimental study on strengthening portal frame light steel structure, organized as soon as possible gantry frame light house steel structure technical regulations CECS102: 2002, pressed sheet metal design and construction procedures "the revision. The combined domestic experience in the use of light steel structure design and construction of the portal frame and appear revise and improve the procedures content, for example, our portal frame the housing carrying capacity reserves smaller than the United States; cross level of plant parapet , roof height difference at our snowy regions, strong winds, areas given special requirements. Two decades, the pace of development of the portal frame light steel structure, construction scale and penetration is unprecedented in the world and domestic, but due to the lack of research and development and technical training, impact of raising the level of the industry as a whole, about the door Frame Light steel structure, steel plate, cold-formed steel design and construction standards and regulations is urgent to modify and improve, and as a revision based on a lot of research needs to be conducted and the necessary pilot studies.