一纹平腹小蜂(Anastatus albilsis A shme ad)是落叶松毛虫卵期的主要天敌之一。通过1984年在室内变温条件下,对该蜂有效积温及发育起点温度的初步研究看出,发育起点温度为7.45±1.02℃,有效积温为369.60±34.15日度,其可靠程度...一纹平腹小蜂(Anastatus albilsis A shme ad)是落叶松毛虫卵期的主要天敌之一。通过1984年在室内变温条件下,对该蜂有效积温及发育起点温度的初步研究看出,发育起点温度为7.45±1.02℃,有效积温为369.60±34.15日度,其可靠程度为90％。此资料可预测一纹平腹小蜂在自然界的发生代数,同时为人工繁殖提供依据,以确保适时放蜂,提高治虫效果。展开更多
Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordi...Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordion. In order to study the lateral-torsional buckling of box beams with corrugated steel webs (BBCSW) under the action of bending moment load, the neutral equilibrium equation of BBCSW under the action of bending moment load is derived through the stationary value theory of total potential energy and further, along with taking Kollbrunner-Hajdin correction method and the mechanical properties of the corrugated web into consideration. The analytical calculation formula of lateral-torsional buckling critical bending moment of BBCSW is then obtained. The lateral-torsional buckling critical bending moment of 96 BBCSW test specimens with different geometry dimensions are then calculated using both the analytical calculation method and ANSYS finite element method. The results show that the analytical calculation results agree well with the numerical calculation results using ANSYS, thus proving the accuracy of the analytical calculation method and model simplification hypothesis proposed in this paper. Also, compared with the box beams with flat steel webs (BBFSW) with the same geometry dimensions as BBCSW, within the common range of web space-depth ratio and web span-depth ratio, BBCSW’s lateral-torsional buckling critical bending moment is larger than that of BBFSW. Moreover, the advantages of BBCSW’s stability are even more significant with the increase of web space-depth ratio and web depth-thickness ratio.展开更多
文摘一纹平腹小蜂(Anastatus albilsis A shme ad)是落叶松毛虫卵期的主要天敌之一。通过1984年在室内变温条件下,对该蜂有效积温及发育起点温度的初步研究看出,发育起点温度为7.45±1.02℃,有效积温为369.60±34.15日度,其可靠程度为90％。此资料可预测一纹平腹小蜂在自然界的发生代数,同时为人工繁殖提供依据,以确保适时放蜂,提高治虫效果。
基金Projects(51408449,51778630)supported by the National Natural Science Foundation of ChinaProject(2018zzts189)supported by the Fundamental Research Funds for the Central Universities,China
文摘Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordion. In order to study the lateral-torsional buckling of box beams with corrugated steel webs (BBCSW) under the action of bending moment load, the neutral equilibrium equation of BBCSW under the action of bending moment load is derived through the stationary value theory of total potential energy and further, along with taking Kollbrunner-Hajdin correction method and the mechanical properties of the corrugated web into consideration. The analytical calculation formula of lateral-torsional buckling critical bending moment of BBCSW is then obtained. The lateral-torsional buckling critical bending moment of 96 BBCSW test specimens with different geometry dimensions are then calculated using both the analytical calculation method and ANSYS finite element method. The results show that the analytical calculation results agree well with the numerical calculation results using ANSYS, thus proving the accuracy of the analytical calculation method and model simplification hypothesis proposed in this paper. Also, compared with the box beams with flat steel webs (BBFSW) with the same geometry dimensions as BBCSW, within the common range of web space-depth ratio and web span-depth ratio, BBCSW’s lateral-torsional buckling critical bending moment is larger than that of BBFSW. Moreover, the advantages of BBCSW’s stability are even more significant with the increase of web space-depth ratio and web depth-thickness ratio.
