Analysis and research of steel structure measurement
Key words: steel frame structure; accuracy analysis; calculation method; 5: goal 1. With the development of urban construction, more and more buildings with steel frame structure are measured during the inspection and acceptance of steel structure engineering. A highly professional and very important job. The accuracy of measuring fl directly affects the quality of the engineering quality fi, which is an important indicator of the engineering quality of the steel structure.
The stadium stand of Changchun Economic Development Zone is a steel frame structure. In order to check the strength and stability of the steel structure and the safety of the steel large-span structure, according to the requirements of Party A, some points on the steel frame and the length of the truss and cable should be measured. And torsion angle, used to detect the accuracy and stability of engineering installation.
2 Accuracy analysis National third-class wire accuracy analysis: Note: "is the number of angle measurements, Mp is the error in the angle measurement, M is the error in the distance measurement. When the wire meets the straight extension, it is calculated that when the number of sides is 8 and the length of the side is M, the national third-class wire can meet our requirements.
Accuracy analysis of the three-dimensional fixed point of the total station. The calculation formula of the three-dimensional coordinates of a point P in the total station: the accuracy analysis of the detection point. We use the TPCON601 total station, two rounds of angle measurement, the distance is read 6 times, and the standard of the instrument The accuracy is said to be mQ = l ", m5 = 2 + 2 Miao W, so, according to the error propagation law, =% can be obtained from the above formula: 2.21mm meets the design requirements.
The layout and implementation of the 3 plan adopts the national third-class wire. The two points q (south side) and 2 (north side) in the football field are known. The two wire loops are arranged. The ring points in the stadium are at On the stand, it is used to observe the points on the main truss. The other ring is used to measure the points on the side truss and the points on the ground anchors and the cable points outside the stadium. The two wire loops are connected at two known points. The wire network is connected to some directions during the measurement process to form a wire network, and then the overall tight adjustment is used.
= 1/85219, reaching the national third-class wire accuracy.
The elevation control uses the second-class leveling fi, and the point on the south side of the football field ((point, value of traverse: lm) is used as the known starting point to form the same network as the plane control, and then perform a tight leveling network adjustment. The results are shown in Table 1. Table 1. Closing difference statistics table No. 1 Geometric conditions: closed level height difference closed difference = 1.5 No. 2 geometric conditions: closed level quotient difference closed difference = -1.8 No. 3 geometric conditions: closed level difference high difference = -0.2 The error of unit weight after the elevation network inspection = 0.05 (mm), which meets the national second-class requirements.
The vertices 3 or 3 'on each tower are measured with two total stations at the same time (3 angles are measured back and the distance is 4 times), and then the average value is obtained; the 1 or 1' point at the bottom of the tower is passed It can be obtained by measuring the points at both ends of the interpolation axis and then taking the average value.
(, 5 (5 '), 6 (6') can not be directly measured, so the upper point of the point is measured, and the height value is subtracted from the radius of the tube to obtain the coordinates of the measured point.
(6 '), 7 (7'), 8 (8 '), because the prism can not be placed, the intersection point is measured by the intersection method, and the measured height is subtracted from the tube radius to obtain the coordinates of each point measured.
The length of the lower point of the cable is obtained by subtracting the design radius of the ear, and the average value is obtained by measuring the actual value of the BP: that is: the lower point of the cable is measured by measuring the center of the two sides of the insertion axis, and then the average value is obtained, and then the distance between the two points in space Formula S (x up x down) 2 Find the cable length.
Table 2 Test results Point number instrument 1 measuring instrument 2 measurement direction intersection mean remarks The measured point of the west truss southwest tower is located at the column to be measured 3 points the west truss southwest tower column 5 dry point The measured point of the west truss is located above the southwest tower at the measured point 18.6 cm (steel pipe half column 4 point diameter) West truss southwest tower column 4 point west truss southwest tower column 3 point west truss southwest tower column 2 point west truss southwest tower column point west truss northwest tower column If point The specific calculation of the direction and angle is as follows: since the spatial coordinates of the two ends of each axis already exist, you can calculate the verticality of the axis of the required column =. ,) 2 The vertical angle of 6 (or 7) to the main truss after the camber of the tower = 4 Analysis of the results of the measurement of fl In the calculation process, due to the excess data, we used several methods to calculate, Table 2 is a few points Method test results.
From the above data, it can be seen that using two total stations to perform high-altitude measurements can not only improve the speed of measuring fl, but also meet the requirements of accuracy. These data also indicate that the total points can also be used for high points that can not be reached by comparison personnel. Method, but also shows the reliability of this method.
5 Conclusions Due to the difficulty of measuring fl and the high precision required for steel frame structural engineering, first of all, in the M measurement process, an accuracy analysis should be carried out according to the accuracy requirements, and the implementation plan should be determined according to the analysis. At the same time, for safety, the level of control can be appropriately increased.
The measurement of steel frame structure is an important task to check the quality of the structure and to judge the safety of the project. It requires high accuracy and reliable test results. Therefore, in the process of measuring fi, some extra data should be measured as much as possible, and as many methods as possible Use, mutual inspection, so that comprehensive analysis and evaluation can be performed to improve the reliability of the measurement results ... Wen 1 Li Yinyue. Engineering survey fi. Surveying and Mapping Press, 1984. 2 Wu Yiqi, Kong Xiangyuan. Precision Engineering Surveying S. Surveying and Mapping Press, 1993.
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