Analysis of static and dynamic stress test results

Analysis of static and dynamic stress test results of tower crane jib

the purpose of this test is to study the working condition of the jib; The influence of dynamic load and the observation of boom head sag. The test results show that: ① the measured stress value of the boom structure is close to the theoretical calculation value. ② For the jib, the stress caused by slewing compound braking and lifting braking is longer than that caused by active treatment, while the stress caused by lowering braking and slewing starting is smaller; ③ The sag of the boom head is relatively large, with a range of 35m. When the lifting load is 3.75t, the maximum sag of the boom head is 74.8cm

through the analysis of the static and dynamic test results of the above tower crane structure, the following conclusions can be drawn:

1. QT jack up tower crane has good structural mechanical performance and safe and reliable operation, This can be proved by the following "" the current popular color trend is black white high gloss surface:

(1) when the jacking pressure is 60t, the maximum stress of the diagonal web member at the support of the jacking beam of the tower body standard section is only 127mpa;

(2) when there is no anchorage, the maximum stress of the main steel of the tower body is 27mpa

(3) when there is anchorage, the maximum stress of the main steel of the tower body is 8927mpa

(5) The maximum stress of the upper chord of the boom is 16927mpa

(6) the maximum stress of the main chord of the jacking jacket is 3927mpa

(7) the stress of other measuring points of the tower body and cap are within the allowable range. The static stress of the tower body and the top web member is relatively small, and the dynamic stress value is also small

2. The dynamic test results show that for the main steel of the tower body and tower top structure, as well as the boom structure, the stress caused by the lifting braking is the largest, followed by the lowering braking, and the rotation is the smallest. For the webs and attachment rods of the tower body and cap, the stress caused by rotation starting is slightly larger, while the influence of various brakes is relatively large

3. The dynamic load coefficient varies depending on the member. Because the number of tests is not enough, it cannot be obtained by mathematical statistics. For the main steel on the top and body of the tower, it is feasible to take the dynamic load coefficient of the boom chord as 1.20

4. For the tower body structure with anchorage, the calculation diagram of the original design is treated as a continuous beam with rigid support. The main steel stress of the tower body calculated by the principle theory decreases alternately along the span from top to bottom, but the measured tower body stress decreases from top to bottom with the same number. Based on this analysis, the anchor support of the tower body should be elastic rather than rigid. Since the measured stress value of the calculated control section of the tower body is close to the theoretical calculated stress value, the original calculation method is still safe and feasible

5. The actual measurement shows that the sag of the jib end of the tower crane is relatively large after the load. In order to reduce the sag of the jib end, the jib head should form an appropriate reverse arch when installing the jib, and the structural self weight of the luffing trolley and hook pulley should be greatly reduced in design. The data shows that: April 27

in short, the structural static and dynamic stress tests show that the tower crane has good performance, safety and reliability, and has working potential