Discussion on deformation monitoring of the hottes

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Discussion on deformation monitoring of large-scale metal frame structure buildings

0 preface with the rapid development of China's economic construction, large-scale concrete buildings with unsupported roof structure continue to be built. Such as large gymnasiums, shopping malls and entertainment venues. Although designers consider the influence of many factors in the process of building design, building deformation monitoring is an indispensable work for safety monitoring in the whole building operation and management stage. It can not only monitor the deformation of the deformation body over time, but also monitor the influence of the dynamic load on the deformation body. The monitoring results can not only provide rare design parameters for the architectural design department, It can also provide quantitative prediction data for the safety of buildings, so as to avoid unnecessary casualties and property losses. This paper discusses in detail how to implement deformation monitoring for buildings with heavy market pessimism of large-scale concrete metal frame structures. 1 layout of deformation monitoring points large concrete unsupported roof structure buildings are generally constructed by "Whether external release agent or internal release agent is used, several groups of metal frames and concrete precast slabs are assembled. During the construction process, the ground is spliced on site, the whole is lifted, and the air is rotated in place. The upper layer is concrete precast slabs, and the lower layer is metal frames connected with each other to support the load from the roof. For example, the metal frame of a gymnasium is made of 195 two specifications () φ 1=40cm、 φ 2=30cm) steel balls and 1200 No. 16 manganese steel pipes are welded to form a rectangular frame with upper and lower chords 3.5m high, 50m long and 40m wide, and the die section is herringbone

due to the constraints of objective conditions, the deformation point can only be set on the steel ball of the metal frame, and the datum point is set at a relatively stable place around the building. The deformation point is measured every time. Therefore, observation marks should be set on the steel balls at the main stress parts before the adjustment and installation of the whole frame. The specific method is to process a diameter  in the center above the steel ball without damaging the overall structure of the steel ball φ= The screw hole of 6 ~ 8mm and the screw matched with it, and the prism sleeve can be put above the screw. When measuring, screw the screw into it, and replace the bolt with rain proof washer when not observing to protect the thread of embedded parts. The breakthrough in the research and development of modified PEEK composite material after the completion of the assembly work indicates that it will gradually replace the utilization proportion of traditional metal products in the chemical industry. After that, a pedestrian riding path woven by metal wires is laid on the lower plane of the metal frame, which is convenient for observation. The above arrangement of points is an ideal arrangement. We have tried to use the method of throwing points to lead the points to the ground for observation, and the accuracy of the results is difficult to achieve. 2 metal frame deformation monitoring according to the design requirements, a gymnasium allows the maximum deformation of the metal frame in the vertical direction to be ± 90mm and the horizontal expansion to be ± 20cm. According to the provisions of the 13th Congress of fig1971, the mean square error of deformation observation is 1/10 Δ~ 1/20 Δ ( Δ Is the maximum allowable deformation value), and it is determined that the mean square error of observation is ± 3mm in the vertical direction and ± 1cm in the horizontal direction

(1) vertical displacement deformation observation

the cross section of the metal frame is composed of 13 steel balls connected with each other (see Figure 1). In order to determine the deformation value in the vertical direction, we measure the height difference between the top of 5 nodal balls (1, 4, 7, 10, 13 from west to East). Using Na2 automatic Anping level to prepare double dividing indium watt ruler for precise leveling. Fig. 1 Schematic diagram of cross section of metal frame due to working conditions, the instrument station can only be set above the steel ball and between the four steel pipes connected with it. The specific method is to nail a square wide wooden frame so that it is tightly cut into four steel pipes, as shown in Figure 2. Then place the tripod on it, and stand on the wooden board laid by the four steel pipes horizontally connected with the steel balls, as shown in Figure 3. In this way, human weight or walking will not produce vibration to the instrument. The observation process is shown in Figure 4. Level instruments (s1-a, sb-13) are set at two points a and B respectively to repeatedly observe five nodes. Both points a and B are measured forward and backward (mainly to eliminate the error of the instrument itself), and the height difference data of the top surface of each ball are collected. 12 recorded data were measured on the top surface of each ball (three readings per round-trip observation at two stations) and averaged. Fig. 2 Schematic diagram of instrument setting-up Fig. 3 Schematic diagram of observer standing Fig. 4 Schematic diagram of leveling observation according to the above observation process, the root mean square error of the change of the height difference of the top surface of the steel ball of a metal frame measured by precision leveling in a gymnasium is ± 0.29mm, and the closure error of the two measurements is less than ± 0.1mm, which is within the allowable error range of measurement, It shows that the observation results are reliable

(2) horizontal displacement and deformation observation

in order to accurately measure the horizontal distance of 1 ~ 13 ball centers in Figure 4, turn the total station (1 + 1) to × 10-6) it is placed at the middle knot ball (ball 7), and the specific layout is similar to the leveling. The prism is placed on the screws at points 1 and 13 respectively for forced alignment, and the horizontal distance from point 7 to point 1 and point 13 is measured. Considering that points 1, 7 and 13 cannot be on a straight line, it is necessary to measure the horizontal included angle of 1 ~ 7 ~ 13 during the operation. In order to reduce the distance to a straight line. In the process of horizontal distance measurement, two sets of data of horizontal distance and oblique distance are collected at the same time, four times for each measurement, and a total of three times for observation. Automatic correction of air pressure and temperature

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