In this paper, weld stress field of Non-preheating with t-joint weld process of high strength low alloy steel Q550 is simulated applying the coupling analysis of temperature and stress field in finite element method(FEM) software ANSYS. The research proves that weld joins can achieve equal strength with the base metal using low alloy high strength steel flux-cored welding wire PK-YJ707A of low hydrogen slag type system. Impact absorbing energy comes up with 107J at -20°C and comes up with 80J at -40°C. After the results of bending, the weld joins have no crack or smaller than 3mm. The mechanical property meets the requirements of the HSLA Q550. In addition, the simulation result is able to more accurately predict the welding stress field that can provide theoretical basis for guiding production practices, reducing cost and improving working environment.

This article investigates the welded joints of HSLA Q550 without preheating and post-heating treatment process. Tensile test, bending test, low temperature impact test, and the impact fractures and joint microstructure observation and analysis are used.The test result shows that the welded joins achieves equal strength with base metal. The average values of the welded joints impact absorbed energy at-20 °C are greater than 40J and at-40 °C its average values are greater than 27J, thus the low-temperature impact energy joint can meet the service requirements of hydraulic support. It shows that choosing proper welding material, developing reasonable welding and post-heating treatment process can cancel the preheating process of Q550 steel welding.

No abstract

It is doubted whether wood columns could be reinforced when their bearing capacities are under requirement, and there are few studies on it. In this paper, eight wood columns, including six basalt fibers reinforced plastic sheet (BFRPS) and two compared members, are tested. Based on the damage characteristics, mechanical performance, bearing capacity calculation method is explored mainly. And the calculation formula used for wood columns strengthened and repaired by BFRPS is formed by analyzing the experimental data. The calculation results based on the formula agree well with the experimental data. The experiment and formula can provide reference and theoretical basis for practical reinforcement construction. Keywords-basalt fiber reinforced plastic sheet (BFRPS); reinforcement; wood columns; bearing capacity; method of calculatingI.

Using BFRPS to increase strength and durability of the structure has recently started to be used as a new technical mean. In this paper, eight BFRPS timber columns under axial compressive loads are tested, and damage characteristics and mechanical properties are studied based on the testing results. Compared with the components which are reinforced and not, the relationship between the effects of bearing factors and increasing degrees can be concluded, providing reference for the similar engineering problems.