Steel structure as a kind of bearing structure system, because it has the advantage of light deadweight, high strength, good plasticity toughness, seismic performance is superior, industrial assembly degree is high, short construction period and the comprehensive economic benefit is remarkable, flexible structure, beautiful appearance, and many other advantages, and thus is more and more should be widely used in industrial workshop, urban rail (subway) car depot warehouses, shopping malls supermarkets such as large span, or span of all kinds of buildings., corresponding to its construction process to build a large reinforced concrete soil foundation for the building and equipment foundation, the buried steel structure (column) and the reinforced coagulation soil foundation bolt connection structure.Because of the large steel structure foundation (upper more than four trustum of a pyramid shape), set not easily fixed bolt dangling, steel structure installation quality requirement is high, so the coupling bolt embedment accuracy become the key technology of the steel structure installation.
Using independent and finalize the design mould for embedded bolt supporting system, by using the theodolite or total station after precise adjustment, proofreading, a complete concrete pouring pile cap, thus to achieve the embedded location accurate.The process is characterized by:
(1) due to finalize the design fixed mold plate embedded bolt, keep the bolt group within the relative position accurately.
(2) system using the independent support and finalize the design mold embedded screw bolt, bolt fine-tuning resistance, high precision operation, the deviation is small.
(3) Make full use of the erection of scaffolding used Φ 48 mm steel tube feet hand lever and fasteners turnover materials, versatility, low cost, can be a lot of saving project investment.
(4) Construction process is simple, the operation personnel easy to master.
2. 1 construction preparation
2. 1. 1 processing anchor bolt anchor bolt should be processing customized according to design requirements and in acceptance, must have the corresponding material certificates and test reports.
2. 1. 2 mold design and processing
(1) according to the embedded anchor bolts with the axis of the concrete foundation of the position, and consider the mold assembly requirements, determine the plane size of mould steel, carved mold steel plate of vertical and horizontal axis cross line, and then press mould axis determine the relative position of the embedded bolt, drill holes.Mould position, aperture to drill hole and the bolt hole of steel structure column, aperture, appropriate ≮ 4 mm steel plate thickness.
(2) the mold steel processing good later can assembly at the scene, the car with length 2. 0 m short feet hand lever, stud using Φ 18 mm steel rebar or Φ 20 mm, stud height should be higher than that of the embedded bolt 5 ~ 10 cm, convenient to use the axis of the steel rule proofreading.
(3) if the concrete foundation top for short cylindrical, can consider to dig a hole in the center of the steel plate, for concrete pouring.
2. 1. 3 measurement precision of the control
According to the engineering design and position coordinates and elevation, encryption and elevation control network layout axis, convenient for the precise measurement of the different parts.
2. 2 the construction sequence
According to the steel structure column layout, first beginning from the Angle or side column, along the longitudinal axis fixed embedded bolts.If multiple span steel structure, should be in the middle across the vertical axis to the vertical drain construction on both sides, to minimize error measurement and construction, improve the overall installation accuracy.
2. 3 independent installation of supporting system
Steel structure design of the concrete foundation size is bigger, the maximum width is 3. 8 m, upper often design for four trustum of a pyramid shape, the height is far lower than the anchor bolt embedded height, moreover steel or wood pattern all has certain flexibility, short of embedded bolt accuracy requirement, therefore, project USES a set of independent supporting system.The installation of support points as follows:
(1) along the longitudinal axis based on both sides of the axis 0. In about 75 m (shall ensure that the ground beam lateral) arrows, along the thread in the foundation pile caps, cushion and basis set upright between pile caps, spacing 2. 0 ~ 2. 5 m.
(2) the stud should be into the foundation soil 30 ~ 50 cm (according to soil soft hard degree), high above the longitudinal bar about 20 mm.Longitudinal rod must ensure that the level set, height should guarantee the embedded bolt
Comply with the design height and leave adjust up and down the mobile space.
(3) the general construction of pile caps is the basis of width were greater than 2. 0 m, can be based on both sides of the vertical rod and the upper level rod with inclined rod connections, form a door glyph;Inclined rod and horizontal stem node spacing of 1. 5 m, guarantee level bar does not produce deflection deformation.
(4) on both sides of the level inclined rod and stem node to erect inclined support (support into the foundation soil depth of about 30 cm), and then in the attached Nearly horizontal rod installation, and based on the upper is composed of horizontal rod and transverse pull rod tic-tac-toe frame, form a space geometrical variations, to ensure that the frame body rigidity and stability
2. 4 shape mold adjustment in place
(1) using theodolite and total station in the support system of tic-tac-toe frame Horizontal axis point layout, drawing form the cross axis, and then to finalize the design mould poles frame on the tic-tac-toe frame on the horizontal bar, made the ten words engraved on the mould steel axis line and the tic-tac-toe frame drawing for, with the foot hand fasteners axle rod and horizontal poles (temporarily not fasten for adjustment).
(2) the finalize the design after the mould is in place, loosen the poles on the fasteners, with a string cable drop from the axis of the tic-tac-toe frame drawing moulds for sheet metal, lightly stroke the poles, to finalize the design mold tiny moving around, using tic-tac-toe frame on the axis of the thread on the precise adjustment, make the shot point and mold carved marks overlap, then tighten the fasteners.
2..5 embedded bolts to install
(1) the embedded bolt from mould steel drilling through, obligate exposed screw length, according to the requirements of design and two nut should be fixed;With a bolt at the top of the elevation level detection, by fine-tuning and nut to conform to the requirements of the elevation, tighten the nut (temporarily don't die).
(2) with level by testing the embedded bolt screw facade in two directions vertical degree, can be mild to break off the screw to adjust, until the two directions vertical degree requirements, complete fastening nut.
(3) when a bolt set every bolt of level and vertical degree adjustment after passing each other with short steel bolt root welding lap connection, make a bolt group form a whole.Such as embedded bolt is longer, can increase one or two weld reinforcement, to ensure that the positioning accuracy and stability.
(4) to make sure that the whole embedded bolt settlement and the tilting, with the foundation reinforced with short steel rack suspension spot welding, and in two short steel bar embedded bolts at the bottom of the diagonal spot welding, support the base development cushion layer.
Based steel rack (5) when the internal space is enough big, does not affect the overall embedded bolt installation, can be installed in the mold before embedded bolts.
2. 6 the review of the embedded bolt
(1) when the foundation pile caps is embedded bolt after the installation is complete, with whole station instrument in the mold plates on layout axis intersection, check whether steel notch pay point and layout axis intersection overlap, if there is error, by loose fasteners tap its lever trimming die, until completely overlap.If the deviation is too big, should loosen its screw fasteners based network frame of reinforcement bar connection, and to adjust.
(2) steel check the foundation pile caps is the distance between the bolt group meets the design requirements, pull on line check the foundation bolt group one row of embedded bolt linear arrangement, if there is any error, repeat the preceding method to correct.
(3) of the longitudinal axis of long steel structure, due to the limitations of visual and instrument, can adopt subsection embedded and encryption methods of control network, and strengthen the review and have embedded bolt measurement, to ensure that the control precision meets the requirements., versatility, low cost, can be a lot of saving project investment.
(4) construction technology is simple, the operation personnel easy to master.