Coarse woody debris (CWD) is composed of dry wood, fallen wood and large branches, and it is an important element for structure and function in forest ecosystems. In this paper, we studied the characteristics of coarse woody debris (CWD) of natural Larix gmelinii forests with different ages in Daxing’anling Mountains. The results show that (1) the CWD volumes in near-mature, middle-age and young forests are 88.55 m3•hm-2, 52.07 m3•hm-2 and 3.96 m3•hm-2, respectively; and their biomasses are 52.96 t•hm-2, 36.22 t•hm-2 and 2.35t•hm-2, respectively. Which indicate that the CWD volumes and biomasses increase with forest ages addition; (2) The CWD volume and biomass follow normal distribution in middle and near-mature forest; (3) the CWD volume and biomass decrease with forest age increasing within decay classes I and II, whereas increase in decay classes III, IVand V; (4) the volume of middle-age and young forests present a near normal distribution with decay class increasing.
There is no a united formula about how to calculate the bearing capacity of a single gravelly pile yet. Recent years, the engineers had developed several theory or experience formulas through many experiments and much studying. But every one has its drawback in calculating. The writer of this paper expresses a new formula bases on Brauns theory to choose by designers.
The spatial analysis model of special-shaped column frame structure is established in ANSYS. The nonlinear dynamic analysis is carried out for the structure by inputting ground motions in one direction. The seismic performance of the structure under rare seismic actions was examined and whether the structure achieved the predetermined seismic aims is evaluated. The results indicates that the structure which under the 8-degree zone designed according to the codes can achieve the predetermined seismic aims under the rarely occurred earthquake actions.
The differential equations about distortional buckling are established according to the distortional buckling mode of cold-formed thin-walled C steel on the lateral and vertical loads. The formula of critical moment is obtained according to the differential equations of bending. This formula can calculate the critical moment if the properties of the section of C steel are given.
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