Steel structure
The bolt of the column bottom plate is installed to control the elevation, and the fixed nut under the column bottom plate is leveled and fixed. After the steel structure column is installed, the upper fixing nut is welded with the embedded bolt, and the lower nut is spot welded. Fill the reserved gap under the column floor with expansive concrete, and wrap the part of the column foot below the ground with concrete (the thickness of the protective layer is not less than 5cm), and make the wrapped concrete at least 15cm above the ground.
The following four kinds of installation defects are easy to occur in the manufacture of connecting holes at the contact surface of main beam and column, connecting plate between main beam and secondary beam and high-strength bolt (1). ◆ The hole of high-strength bolt is slightly larger than the diameter of high-strength bolt 1~2mm. When the installation hole can't be used, the low-hydrogen covered electrode matched with the base material can be used to fill the hole, and the hole can be drilled again after polishing, instead of gas cutting reaming or gas welding drilling. ◆ The position of the first row of holes from the edge of the main beam and column and the edge of the web shall be subject to 5cm, not in the middle of the flange plate of the main beam or 5cm from the edge of the flange plate. The drilling must be accurate when making, so that the installation can proceed smoothly. ◆ At the connection plate between the steel column and the main beam, the horizontal stiffening plate of the column should be set at the upper and lower flange plates of the beam connection hole, or bolt connection can be adopted, that is, the flange plate adopts the method of single V-shaped groove and gasket, and is fully welded instead of filling the end gap with steel heads with different strengths. ◆ At the intersection of the main beam and the secondary beam, the secondary beam does not enter the flange of the main beam, the bolt hole is too far away from the web of the main beam, and the connection gap between the main beam and the column, the main beam and the secondary beam shall be subject to 1cm. (2) The welding spots at the ends of the main beam and the secondary beam shall be polished and derusted in time. The friction surface of high-strength bolts must be clean and tidy, and there must be no flash, burr, welding scar and dirt. Sand blasting and inorganic zinc-rich primer should be used in this part. , to achieve the effect of anti-slip, rather than painting anti-rust paint. (3) When fastening high-strength bolts and nuts, a special manual torque wrench should be used to tighten them symmetrically from the center to the edge. The initial and final screwing should be carried out twice, and it is strictly forbidden to complete them at one time. After reaching the design torque, the bolt ends shall be marked with chalk to avoid distortion. The construction site generally requires an initial torque of 220N? M, the final torque is 374~5 10N? M, generally take the test value as 440N? m； High-strength bolts must also be tested for anti-slip coefficient of friction surface and re-tested for prestress of high-strength bolts.
Key points of welding: preparations should be made before welding, and the welding seam should be uniform, neat and flat, and make a smooth transition with the base metal. Weld width requires the depth-width ratio of each weld to be1:1; Generally, the height of the weld is twice the width; The covering width of each side of the weld is 2 ~ 4 mm. 90 weld should be 45. There should be no quality defects such as cracks, incomplete penetration, root shrinkage, undercut, poor joint, surface porosity, slag inclusion, flash, arc pit, burn-through and arc scratch on the weld surface that affect the dynamic load. Allowable deviation should be paid attention to in the size of welding leg. The deviation depth of incomplete penetration is not more than 1mm, and the length per 10cm is not more than 2.5cm. Generally, the combination of full penetration fillet weld and butt weld shall not exceed 10 mm. ..
Other (1) components must be leveled during transportation and stacking, and the pad points should be reasonable, and the upper and lower pads should be on a vertical line to avoid uneven stress and deformation of the pad points. (2) Components shall be fixed by reasonable welding sequence and welding process or fixtures and fixtures, and then welded to prevent warping and deformation after welding. (3) The fabrication, hoisting and inspection of steel members shall use a steel ruler with uniform accuracy, and the fabrication dimensions of the members shall be strictly checked, and the allowable deviation shall not be exceeded. (4) The welding construction shall be carried out in strict accordance with the specification requirements to minimize welding defects. (5) During installation, reaming or welding shall not be carried out at will, and it shall be handled according to specifications or negotiation requirements after consultation with the design unit. (6) The welder shall have the license and number, and the welding parts shall be inspected and recorded according to the number. If all welds fail to meet the requirements after visual inspection, they should be re-inspected after repair welding. (7) When installing, it is necessary to temporarily fix it with the installation bolts, and then install and replace the high-strength bolts after adjustment and fastening.
frame construction
Avoid the displacement of the main reinforcement in the frame column. During the construction of frame structure, attention should be paid to the firm rooting of fixed column rebar, and the spacing of column rebar and the thickness of protective layer should be controlled to meet the requirements to avoid displacement. Pay attention to ensure the correct position when arranging the foundation reinforcement, and add stirrups as required; If the bottom of the column reinforcement is inconvenient to fix, it must be fixed by welding; Control the thickness of protective layer of main reinforcement. After completion, precast cushion blocks should be added in sections or reinforced supports should be set up. To ensure the qualified reinforcement ratio of the structure, attention should be paid to the reinforcement ratio of the members of the frame structure to meet the construction requirements and avoid pursuing high reinforcement ratio. The reinforcement ratio of longitudinal tensile reinforcement at the beam end shall not exceed 2.5%, and the total reinforcement ratio of column reinforcement shall not exceed 5%, which shall be symmetrically arranged; For parts prone to small eccentric tension (such as corner columns and side columns, etc.). ), the reinforcement ratio can be appropriately increased, longitudinal reinforcement with larger cross section or the number of reinforcement can be increased. In the deformation construction of column section, attention should be paid to controlling the stiffness of formwork or support when pouring concrete, otherwise it will affect the concrete forming effect. When setting ring beam fixture outside the column, the spacing scheme should be made according to the column section size and template material, generally 500 ~ 800 mm If the column section size is greater than 500mm, checking calculation should be carried out to determine whether it is necessary to set through fastening bolts to ensure the overall stability of the structure, avoid the vibrating rod touching the template during pouring, fix the upper and lower ends of the column template, and appropriately add external formwork hoops. Avoid stirrup leakage. The binding process of stirrups during installation is unreasonable. If the whole stirrup is in place outside the formwork, all kinds of steel bars are bound and put into the formwork, then the stirrup in the core area is installed, and finally the negative reinforcement of the primary and secondary beams is installed. In order to avoid the difficulty of resetting caused by too many steel bars in the joint, the stress state should be considered to make it shift upward or downward. Before laying the infilled wall, the builder must make technical disclosure to the operators according to the construction scheme, and at the same time put forward specific requirements for the operators according to relevant specifications, such as mortar mortar joint should be controlled at 8~ 12mm, and mortar fullness should not be less than 80%. In particular, it should be pointed out that the joints of infilled walls, frame columns and shear walls must be driven with expansion bolts at specified intervals, and then Rachel steel bars with diameters and lengths meeting the requirements of specifications are welded in the mortar joints of masonry and buried; When bricklaying or masonry is about 200mm away from the bottom of frame beam or cast-in-place slab, it should be left standing for at least one week, and then it should be laid obliquely to the bottom of beam (or slab) with clay bricks or blocks.
brick construction
Seismic structure of seismic infilled wall-setting of tie bars between masonry and column or concrete wall. Because the position of Rachel is inconsistent with the modulus of block, there are problems in the length and hook of Rachel. In order to ensure the seismic performance, the method of planting reinforcement is often used in construction, but the position of the main reinforcement should be detected. For the commonly used embedding methods in masonry, problems such as offset of embedding position and non-correspondence with masonry mortar joint should be avoided. Reinforcement shall be buried by setting concrete blocks locally between masonry and columns, and Rachel reinforcement shall be pressed into mortar joint through a certain inclination in concrete. (1) When constructional columns are installed on the filling wall, the column rebar should be reliably connected with the beam at the top (the lower part should be inserted into the beam with steel dowel), and the rebar should not be disconnected. The correct way is to weld embedded parts and column reinforcement at the bottom of the beam. In some cases, it is unacceptable to remove the concrete protective layer at the bottom of the beam and then weld the column rebar with the main rebar at the bottom of the beam, which will cause certain damage to the beam. (2) For some hollow bricks, if core columns are designed, especially in seismic fortification areas, concrete structural columns should be changed. Generally, core column concrete pouring is not easy to be vibrated and compacted, and the quality of poured concrete is difficult to check and deal with. (3) The use of too thin infilled wall masonry materials in some projects should be restricted. If the engineering design adopts 100mm thick autoclaved aerated block as the masonry material for filling the wall. The height of this part of the wall is 4.0m, and the length of some walls exceeds 5m. Time-controlled infilled walls generally do not bear the pressure of the upper component load, but only play the role of enclosure or partition. But in the construction site, we can often see some infilled walls, which have been laid before pouring the upper concrete members, and then pouring concrete directly on the masonry, which is harmful, especially some brick-concrete balcony cantilever lower masonry and some 120mm thick wall masonry. For the former, the cantilever beam concrete is poured directly on the lower filling wall, which changes the structural stress of the cantilever beam; For the latter, 120mm thick wall is weak and not suitable for bearing. At the same time, if the construction is carried out according to this method, under the load of the upper component, it may cause quality problems such as vertical cracking of the infilled wall or cracking of the plastering layer. On-site construction and supervision personnel should control the masonry time of the infilled wall and stick to post-masonry. The above wrong construction methods shall not be continued.
grid structure
Bulk at High Altitude (1) In order to ensure assembly accuracy and reduce accumulated errors, small assembly units or bars can be assembled directly at high altitude. During the assembly of grid structure, the position, elevation and deviation of reference axis should be checked at any time and corrected in time. (2) When installing and assembling the bracket, the position of the support point on the bracket should be located at the bottom chord node. Support should check its bearing capacity and stability, and carry out pressure test when necessary to ensure safety and reliability. Measures should be taken under the pillar to prevent the bearing from sinking. (3) In the process of dismantling the support, the stress concentration of individual support points should be prevented. According to the structural gravity deflection value of each support point, the support point will be dismantled in stages or by equal step descent in proportion, and each step shall not exceed10 mm. ..
Integral lifting (1) The integral lifting of grid structure can be realized by installing lifting equipment on the structure, or by lifting the grid structure at the same time of column slip-form construction. At this time, the grid can be used as a lifting platform. (2) To improve the service load capacity of the equipment, the rated load capacity should be multiplied by the reduction factor, and the through-heart hydraulic jack should be 0.5 ~ 0.6; The electric spiral elevator can be 0.7 ~ 0.8; Other equipment is determined by test. (3) When hoisting the grid, it shall be carried out synchronously. The allowable lifting difference between two adjacent lifting points and the highest and lowest lifting points shall be determined by checking calculation. (4) The resultant force point of lifting equipment should be aligned with the lifting point, and the allowable deviation value is 10 mm ... The stability of the lower supporting column of integral lifting method should be checked.
membrane structure
When installing the membrane structure (1), the construction conditions should be strictly controlled: the membrane structure installation should be carried out under the condition that the wind force is not more than 4; During installation, pay full attention to wind speed and direction to avoid vibration. At the same time, the suspension and continuation of the project should be decided according to the rainfall degree, and rainwater accumulation should not occur during installation. (2) When tensioning, the sequence and size of batch tensioning shall be determined, the tensioning speed shall be controlled, and the overstretching size shall be determined according to the characteristics of materials. When the next working procedure or adjacent project starts construction, protective measures must be taken for the completed membrane structure to prevent damage. (3) Isolation layers must be set between membrane surface supporting structures, and no direct contact is allowed. Before the membrane surface is unfolded, fastening splints should be installed, and the spacing between the splints should be no more than 2m. According to the span of the membrane structure, adjust the spacing between the centers of the splint, and the bolts and nuts of the splint must be tightened in place. (4) The installation of membrane structure spinal cord and valley rope shall be carried out according to the requirements of construction organization design. During the installation of membrane structure, temporary ridge ropes and valley ropes should be used before installing them. To prevent the unfinished membrane structure from shaking too much under wind load. The assembly of anchor heads of chord and valley of membrane structure must be carried out in strict accordance with technological standards, and the chord and valley should be tensioned in place. Construction records shall be made for tensioning values with control requirements, and tensioning travel records shall be made for those without control requirements. (5) During quality control, the processing machinery and equipment shall be comprehensively inspected and inspected. According to the requirements, do a good job in the heat sealing strength test of film materials. Strengthen the technical disclosure process, and handle the strict training and technical disclosure by the squad leader for the personnel involved in membrane treatment. (6) The blanking member should check the variety, model and color of the membrane material, be familiar with the size of each membrane material, accurately blank and mark it, put the cut membrane materials in order, and proofread them with the form-finding cutting diagram again before sewing them in order. In the process of processing, the sealing temperature and sealing time specified by the film material should be strictly observed. The processed membrane materials are numbered and packaged and delivered to the project site by the logistics team. In the process of construction of various structures, we should try our best to reduce cross-operation. When crossing, pay attention to the following aspects. (1) The person in charge of construction shall organize all parties involved in crossover operation in advance, and stipulate the construction scope and safety precautions of all parties; Each working procedure should be closely coordinated, and the construction site should be staggered as far as possible to reduce interference; For vertical cross operations that cannot be staggered, strict and firm protective isolation facilities must be set between layers. (2) The channels in the crossover workplaces should be kept clear; Dangerous entrances and exits should be fenced or hung with warning signs. (3) Isolation layer, hole cover plate, railing, safety net and other safety protection facilities are strictly prohibited to be dismantled at will; If it must be demolished, it shall be approved by the original erection unit, and it shall be restored to its original state immediately after the project is completed and accepted by the original erection unit; It is forbidden to tamper with equipment, tools and safety facilities that are not within the scope of work. (4) During cross construction, it is forbidden to throw tools, materials and leftover materials up and down, and use tool bags, laundry baskets or hanging cages for lifting. It is forbidden to accept materials or stay under the hanger. (5) shuttering, painting, wall-building and other types of work shall not be operated in the same vertical direction when the upper and lower columns cross. The location of the lower operation must be outside the radius of the possible falling range determined by the upper height. If the above conditions are not met, a safety protection layer should be set up. (6) When dismantling steel formwork and scaffolding, there shall be no other operators below. (7) After the steel formwork component is dismantled, the temporary stacking place shall be not less than 1m from the floor edge and the stacking height shall not exceed1m.. It is strictly forbidden to pile up any dismantled objects on the edge of the floor, the opening of the passage and the edge of the scaffold. (8) Since the second floor of structural construction, all personnel access openings (including derrick and construction elevator access openings) shall be provided with safety protection sheds. Double protection should be provided for cross operations with a height exceeding 24 cm. (9) Due to the above construction, objects or passages that may fall within the swing range of the crane boom must be built within the affected range.
Other preventive measures
The concrete pouring on the floor is uneven, and the impression of the stress surface is poor. It is required that the elevation control points led by labor services can be controlled by pulling wires in each bay, and the height of concrete should be measured by pulling wires during concrete pouring. The relevant building number and technicians should check the elevation, the personnel on duty should be on duty, and the receiving surface should always be tracked and controlled. The plane rough surfaces of walls and columns should be leveled, and the roots should be kept flat, so as to avoid slurry leakage, root rot and dislocation caused by uneven formwork support next time, and the concrete should be chiseled before and after the final set. Hanging formwork is supported by shaped square steel formwork, which must be reinforced firmly without floating, sinking or deviation. Control the elevation when shuttering, and protect the finished product when ripping. Stair step is the main channel to watch the main building, so it is necessary to ensure the unity of step size and the impression of closed surface. It is suggested to refer to the technological practice of Tianshun Labor Service for stair stepping. There is no iron wire and step by step for stepping reinforcement, and the stair slab reinforcement pad is laid in place. Small components such as constructional columns, bay windows, air conditioning panels, air shafts, etc., pay special attention to details to ensure that the structural dimensions and stress surfaces are in place, and there is no obvious dimensional deviation between the upper and lower floors, so it is difficult to repair the floor-to-ceiling frame after it is removed. Exterior window openings should focus on formwork support and acceptance, and take care of them from top to bottom. Exterior wall, elevator shaft lateral formwork top should be straightened to prevent distortion. The surface of details should be in place, and the details and internal corners of water and electricity pipe roots, straight embedded parts, pay-off holes, etc. should not be closed with a grinder, but should be manually compacted and polished with a trowel. Steel bar displacement, for the labor force with more steel bar displacement, strengthen control in each process of setting-out positioning, shuttering and pouring. When pouring concrete, the concrete worker should reset it in time after prying the steel bar, or require the labor force to make ladder bars with waste steel bars to strengthen the steel bar displacement control. For the template, the flat-fell seam of the template should be less than 1mm, otherwise double-sided adhesive should be pasted, and double-sided adhesive must be pasted at the corner of yin and yang. It is forbidden to use iron wire to pull the template when shuttering. Template edge stare blankly and falling concrete should be cleaned up in time to avoid concrete pollution and waste. Set up a double-layer protective corridor, the top of which can prevent penetration.
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