Steel Engineering and Technology Encyclopedia

Steel Engineering and Technology Encyclopedia

Hainan Steel Companies specializing in plant mainly refers to the main load-bearing member is made of steel composition. Including steel pillars, steel beams, steel base, steel roof (of course, relatively large span of the plant, are now basically a steel roof trusses), steel roof, attention steel wall brick wall may be used for maintenance. As China's steel output increases, many are beginning to use a steel plant, specifically also points of light and heavy steel plant.

1, light steel structure construction quality, high strength, span.

2, steel construction, short construction period, the corresponding lower investment costs.

3, high fireproof steel construction, anti-corrosion.

4, easy to move steel construction, recycling pollution.

First, the steel member is detected and the steel plant in Hainan

1, the detection and accounting steel rod slenderness ratio, according to the "Steel Engineering Specification detection" predetermined measuring rod size, slenderness ratio should be based on the actual size and other accounting rod member.

2, the connecting steel support system, according to "Steel Engineering Specification detection" predetermined detection; member of the support system size, according to "Steel Engineering Specification detection" predetermined measured; according to the design drawings or relevant design specifications verified or evaluated.

3, a cross-sectional width to thickness ratio of steel member, according to "Steel Engineering Specification detection" predetermined measurement member associated sectional dimension, and accounting, according to the design drawings and related specifications to be assessed.

Second, Hainan Steel Structures Painting

1, the quality of steel protective coatings, should the current national product standard for paint quality requirements for testing.

2, the surface rust grade steel, can be used with existing national standards "before painting steel surface rust grades and rust grades" GB8923 predetermined image control observation to determine.

3 different types of paint coating thickness, respectively, using the following method should be detected:

(1) film thickness, the film thickness can be used to detect, the number of sampling member shall not be less than the minimum capacity of the standard table 3.3.13 of the class A test sample, nor should be less than 3; each measuring 5 , the values ​​for each of the three distance measuring points 50mm dry film thickness average.

(2) fire retardant coating on the thin coating thickness, coating thickness tester can be used to detect, measure method should comply with "fireproof coatings application of technical regulations" CECS24 of.

(3) thick fire retardant paint coating thickness should be used to detect the stylus and ruler, measurement methods should be consistent with the provisions of "fireproof coatings application of technical regulations" CECS24 of. Coating thickness value and the deviation should be required to "Steel Construction Quality Acceptance" GB50205 be assessed. 6.7.4 appearance quality coating, can be detected and evaluated in accordance with the provisions "Steel Construction Quality Acceptance" GB50205 according to the different materials.

Third, the steel frame of steel

1, steel truss bearing capacity of detection can be divided into nodes, weld size and bias, not flatness rods and steel truss deflection and other items.

2, test steel truss bolts welded spherical joints and spherical joints bearing capacity, should be "grid structure Engineering Quality Inspection and Evaluation Standards" JGJ78 requirements. On the existing bolts ball grid nodes, the nodes can be removed from the structure to the ultimate bearing capacity test nodes. When the interception bolt ball node, should take measures to ensure security.

3, steel truss welds, ultrasonic flaw detection method can be detected, the detection and evaluation of the operation should be "welded spherical joints steel truss weld ultrasonic testing and quality grading" JG / T3034.1 or "steel bolt ball node truss weld ultrasonic testing and quality grading "requirement JG / T3034.2 be.

4, the steel truss weld appearance quality, should be "Construction Quality Acceptance of Steel Structure Engineering" GB50205 requirements for testing.

5, solder balls, ball screws, high strength bolts and rods deviation detection, detection methods and allowable deviation value should be required to "grid structure Engineering Quality Inspection and Evaluation Standards" JGJ78 implementation.

6, the wall thickness of steel pipe truss rod, can be used to detect ultrasonic thickness gauge, should be removed before finishing layer detector.

7, steel truss rod without the axis of flatness, the cable can be used to detect, it is not straight shall not exceed the length of the rod member thousandth.

8, steel truss deflection, can be used to detect water level or laser rangefinder, every half points measured across a range of not less than three, and the span should be a measuring point, end bearing end of the measuring point should not be more than 1m.

Fourth, the structure and properties of solid steel load test and dynamic test

1, for large complex steel structures can be carried out in situ non-destructive real load testing, inspection and structural performance directly. Structure and properties of solid load test according to the provisions of Appendix H of this standard will be. Loading coefficient and a decision in principle determined according to the provisions H.2 can also be adjusted according to the specific circumstances of the appendix.

2, when the bearing capacity of the structure or member of doubt, can be carried out full-scale model or prototype load test. The test shall be entrusted to specialized institutions have sufficient equipment capacity will be. Should develop detailed test program prior to the test, including test purpose, test piece selection or production, loading apparatus, measuring points and test equipment, procedures, and test results of the evaluation method is loaded. Appendix H to develop test programs can and should be agreed by the parties concerned before the test.

3, for large and important new steel structure system, should the actual structural dynamic tests to determine dynamic parameters of the structure of natural cycles. Dynamic test should comply with the provisions of Appendix E of this standard.

4, stress steel rod, the choice of resistance strain gauges, or other effective methods to detect the actual condition.

Fifth, the second largest steel plant defects

China's modern construction steel construction defects. Steel in construction has been adopted by many companies, but the majority in order to optimize the structure, resource conservation, recycling, only the implementation of the new construction of steel structures. In the steel plant it has also brought a lot of flaws and potential safety problems. In the steel companies in the majority of business owners to promote weight steel advantages while ignoring the defects and safety risks.

Steel Works produces analytical quality problems; steel works difficult to guarantee quality for many reasons, but also very complicated issue both processes improper, there are also problems caused by violation of process operation, as well as due to the level of technology and responsibilities of construction workers problems caused by the heart, as well as decision-makers mistakes caused by quality problems.

Presence of (a) steel itself is the problem

A unit in the processing of building a box-shaped column 1200 * 1200 * 60 in the welding process, suddenly found 60mm emerged as tearing the web plate, clearly visible cracks in the thickness direction of the plate in half after NDT detected crack depth occurs at a depth of about 3mm, while another batch of the same type in the same cutting board a few parts for testing, found the mezzanine board memory, poor quality rolling is the main cause of quality problems. In the process of welding due to welding stress generated by welding the interlayer material opened. Hence there slab thickness direction tear phenomenon Analysis: Due to the use of part of the special nature of the components in the use of the web as a member, along the longitudinal direction of the welded parts in the upper and lower welding formal opening of the full penetration groove stiffeners force due to the presence of layered inner plate, welding stress generated by welding outwardly thereby releasing tear plate thickness direction. You can take several measures to deal with the actual situation:

(1) a large number of steel sandwich quality issues that exist within the mill itself produced during the rolling process, has exceeded the national standards requirements, they can send someone to verify the requirements of mills, steel mills in consultation with the return or exchange deal with;

(2) If the amount is less sandwich technology sector and may seek the views of the owners, will feedback to the mills, to take remedial measures to construction problems, according to the results of non-destructive testing in problem areas using all gouging gouging open over the depth of their own, and then with an equal strength welding material to fill after the completion of the surface treatment, after a predetermined time for NDT inspection, while the same member sampled for physical and chemical testing, to meet the design specifications can continue to use;

(3) Under the supervision witness parts cut off, back into the condition of the plate, Replacement parts for non-load-bearing and non-critical parts or as an auxiliary use, after completion of the prescribed time NDT testing, make a record.

(B) appear in the construction process in question

Quality problems during manufacture and are more prone to it after a very difficult process mainly special process and important step. General Procedure for quality problems proportion of small. During the construction process in the above, there is a special process of welding, painting, important steps have cutting, assembly.

1. welding process. This process belongs to the hidden works, one process quality problem is most likely to occur from 2004, a company's product quality report statistics show that in the process of quality problems: Because the weld seam quality due to failure rates as high as 80% , followed by the procedure due to technical problems and improper operation of the operator and cause weld quality problems about 10%, so a direct impact on project quality issues are the main issues, so this type of problem must be applied by a professional testing company specializing in detection tools can detect, judge it, generally based on the type of defect in the weld into slag, incomplete fusion, such as porosity.

2. The coating process. This step is part of covert step for building functional impact on the structure of less than. Also easier to process quality problems. Process quality problems mainly in: paint off a large area of ​​the surface member and a partial loss, the film off the surface of the member, sagging, the film thickness is not enough, uneven distribution of film thickness, film color color larger.

3. Stake cutting step. Before this process belongs to the leading member before processing, its quality to the next step there is a direct impact, and even lead to cutting scrap all parts of this happening is very common, so for the next feed strengthen quality control process is very important and necessary. This process produces quality problems mainly in: For elongated and thin types of components in the cutting deformation more powerful; cutting gas cutting surface due to the presence of internal or sheet metal and slag caused by uneven distribution of ingredients appear horse tooth pattern , gnarled, nicks depth exceed the standard; gas cutting or sawing parts without considering the subsequent process of shrinkage caused by excessive size parts; batch process documentation components by mistake which led to the scrap; cutting cut size severe than the standard requirements.

4. The assembly process. This process plays in the quality of the processing member in an important position, which greatly influenced the quality of the procedure, so before the assembly to strengthen the monitoring process is very important. This process produces quality problems mainly in: Parts assembly position error, such as pretend 3450mm 4350mm; using the wrong parts, should have been # 2 parts assembly parts, assembly # 3 is another member; parts assembled in the correct position on the error, such as aperture plate 45mm originally outward, toward the actual contents of the 45mm; assembly parts assembly clearance exceeds specifications and technical documentation requirements, the gap is now 3mm 7mm; some parts no after correction to be assembled, after completion of the assembly already exists no way to eliminate the distortion deformation; operatives is the easy way to cut without permission on the part caused excessive size hole location;-chip area without surface treatment; assembly errors caused by errors caused by paper size .

Six of the nine advantages of steel plant in Hainan

1, shock resistance: low-rise villas roof mostly sloping roof, so the roof structure basically is made of cold-formed steel members made of triangular roof truss system, light steel structural member after the seal plate and finished gypsum board formed very strong "plate rib structure system," the ability to have a stronger structural system to resist seismic and horizontal loads applied to the seismic intensity of 8 degrees above areas.

2, wind resistance: steel structure building light weight, high strength, good rigidity, deformation ability. Only one-fifth the weight of buildings of brick and concrete structure, resistant to 70 meters per second hurricane, so that life and property can be effectively protected.

3. Durability: light steel structure residential structure used in all cold twisted thin steel component system composed of high-strength cold-rolled steel reinforced using super corrosion galvanized sheet manufacturing, effectively avoid the effects of corrosion of steel in the construction and use of the process, increasing the light steel life member. Structural life of up to 100 years.

4, insulation: thermal insulation materials used in fiberglass cotton-based, with good insulation effect. For external wall insulation board, effectively prevent the wall "cold bridge" phenomenon, to achieve a better insulation effect. R15 insulation around 100mm thick cotton thermal resistance can be equivalent to 1m thick brick wall.

5, noise: the effect of noise is an important indicator to assess residential, light steel system installed windows are made of hollow glass, sound insulation, sound insulation up to 40 decibels; the wall by the light steel keel, gypsum board insulation material composed of its sound insulation up to 60 decibels.

6. Health: dry-construction, to reduce pollution caused by waste on the environment, housing material can be 100% recycled steel, other materials may also be supporting most of the recovery, in line with current environmental awareness; all materials green building materials, to meet the ecological environment requirements, conducive to health.

7. Comfort: light steel wall using energy-efficient system, with respiratory function, can regulate indoor air humidity; roof with a ventilation function, can be formed between the internal air flow over the house, to ensure internal roof ventilation and cooling requirements.

8, Shortcut: all dry construction jobs, seasonal effects from the environment. A 300 square meters around the building, just five workers 30 working days to complete renovation from the foundation to the whole process.

9. Environmental Protection: 100% recycled material, truly green pollution.

10, energy: all use energy efficient walls, insulation, heat insulation, sound insulation, up to 50% energy saving standards.

Seven, shortcomings in the quality of the steel works

(A) Complexity: Steel Project Construction Quality complexity of the problem, mainly in the range of factors that lead to quality problems, the cause of quality problems are complex, even if the quality of the same nature, because sometimes not the same, so analysis, judgment, and deal with quality problems adds to the complexity. Such as welding cracks, which can occur in the weld metal, heat affected may also occur in the base material, either in the weld surface, but also in the internal weld; fracture strike parallel to the bead can also be vertical to weld cracks can be both cold crack, it may be hot crack; welding material also causes improper selection and welding preheat or hot inappropriate points.

(B) Severity: severity of the problem of construction quality performance in steel projects: Generally, the impact of construction carried out smoothly, resulting in schedule delays, cost increases, severe, building collapse, causing personal injury, damage to property caused by adverse social impact.

(Iii) variability: steel construction quality problems with the extension of the outside world will change and the time and constantly evolving, quality defects gradually reflected. For example, weld steel member due to the stress of change, so that the original weld cracks cracks: As the role of hydrogen after welding activities can be a delay in the weld cracks. Another example is the member long withstand overload, the steel components to produce bending deformation under the arch, resulting in problems.

(Iv) frequent: As China's modern buildings are in concrete structures mainly engaged in construction management and technical staff for production and construction technology of steel is relatively unfamiliar to mainly migrant construction workers are less specific scientific method to understand the construction of steel structure engineering, construction process leading to frequent accidents.