The steel structure under the action of alternating load for a long time is prone to fatigue failure and affects the safety of the engineering structure. For steel structures in complex environments such as corrosive media and fires, the remaining fatigue life is more difficult to predict theoretically. To this end, the article carried out fatigue tests on Q420qD high-performance steel cross joints under three different working conditions, established a 95% survival rate $$S{ - }N$$ S - N curves, and analyzed the effects of corrosive media and high fire temperatures on its fatigue performance. And refer to the current specifications to evaluate its fatigue performance. The results show that the fatigue performance of the cross joint connection is reduced under the influence of corrosive medium, and the fatigue performance of the cross joint connection is improved under the high temperature of fire. When the number of cycles is more than 200,000 times, the design curves of EN code, GBJ code, and GB code can better predict the fatigue life of cross joints without treatment, only corrosion treatment, and corrosion and fire treatment, and all have sufficient safety reserve.

Mass concrete is widely being used in the construction field, especially for the foundation of super high-rise building. In the initial stage of pouring completion of mass concrete, lots of heat generated from the cement hydration will lead to a high temperature inside of concrete. When the temperature difference between the inner and outer of concrete exceeds the limited value, thermal stress will be greater than the tensile strength of concrete, which may cause hazardous penetrating cracks of the structure. To ensure the safety and durability of concrete structure, necessary measures should be taken to control the temperature rise and construction quality of concrete. Taking a super high-rise building project as an example, this paper introduces several effective solutions to resolve above problems. The technical measures such as enhancing the concrete quality, controlling temperature rise, strengthening temperature monitoring would be detailed illustrated. Meanwhile, valuable suggestions achieved from this practical project are proposed in order to guide the structural design and on-site construction of similar projects.

In order to meet the requirements of mechanical recovery of residual film before tillage in Xinjiang cotton field irrigation area, a combined machine for cotton straw returning and residual film recovery with the function of secondary throwing was independently developed, and the field test of scavenging rate and mulching film hybrid rate was carried out to determine the optimized performance of the machine and tools. Moreover, the comprehensive prevention and control technology model of mulching film pollution was established in Xinjiang cotton field irrigation area. In the end, the system and application basic theory of mechanization recovery technology for residual film before tillage in Xinjiang were created, so as to contribute to the “White Pollution” control in Xinjiang.

Nowadays steel space truss structure becomes an increasing trend, but its fire resistance performance, especially in practical project, is seldom researched. The residual bearing capacity of fire-damaged space truss structure, the force-bearing condition of member bar used in fire-damaged space truss, and the accuracy of conventional temperature field analysis method are all hot spot issues to be solved. This paper, based on a steel space truss demolition project of fire-damaged tall building, elaborates the adopted method of cutting steel member bar, and meanwhile verifies the security and efficiency of that cut technology as well as the accuracy of the finite element analysis by comparing monitoring data with finite element analysis. Additionally, this paper discusses a specific analysis of eccentric force in member bar which encountered during demolition process, and proposes the solution. Keywords-internal force monitoring; fire-damaged space truss structure; stepwise-baking cut technology; eccentric forceI.

Designing a top-stem-cutter part for the top-cutter machine. Adams was used to analysis the moving simulation, with the help of it, the normal structure and dimension were inspected and verified. In this paper, the tract of the top-stem-cutter part analyzed by Adams was matched the result from the theoretical calculations; the model and structure also had been analyzed by Ansys, which provided a way to analysis and verify the machine, and analysis of the model can get the nature frequency of the top-stem-cutter part, and it had given us a way to lower frequency of machine; the structure analysis provided that the stress of the top-stem-cutter part should be lower than certain value.