by The copyright of this article comes from “Beijing Review Association” and belongs to the original author.
First, the new standard unified standard for reliability design of building structures gb50068-2018 improves the safety level compared with the old standard gb50068-2001.
Announcement No.
263 of the Ministry of housing and urban rural development of the people’s Republic of China on Issuing the national standard unified standard for reliability design of building structures is hereby approved as the national standard, No.
gb50068-2018, which will be implemented from April 1, 2019.
Among them, Section 3.2 1、3.3.
Article 2 is mandatory and must be strictly implemented.
The original unified standard for reliability design of building structures (gb50068-2001) shall be abolished at the same time.
The most noticeable changes of the Ministry of housing and urban rural development are: the partial coefficient of permanent action (dead load) is adjusted from 1.2 to 1.3; variable action The partial coefficient of (live load) shall be adjusted from 1.4 to 1.5.
The new standard 8.2.9 partial coefficient of action of building structures shall be adopted according to table 8.2.9.
Table 8.2.9 application of partial coefficient of action / partial coefficient of action of building structures when the action effect is unfavorable to the bearing capacity and when the action effect is favorable to the bearing capacity γ G1.
3≤1.0 γ P1.
thirty-one γ Q1.
50 old standard 7.0 4.
The partial coefficient of load shall be adopted according to the following provisions: 1.
Partial coefficient of permanent load γ G.
When the permanent load effect is unfavorable to the bearing capacity of structural members, 1.2 shall be taken for equations (7.0.2-1) and (7.0.2-3) and 1.35 shall be taken for equation (7.0.2-2); when the permanent load effect is favorable to the bearing capacity of structural members, it shall not be greater than 1.0.
2 ﹐ the first and I variable load partial factors γ Q1 and γ Qi, when the variable load effect is unfavorable to the bearing capacity of structural members, it shall be taken as 1.4 in general; When the variable load effect is beneficial to the bearing capacity of structural members, it shall be taken as 0.
The increase of structural safety is undoubtedly a good thing.
At the same time, it has led to the increase of structural cost to a certain extent.
In view of this, we believe that it is necessary to carry out the overall calculation, comparison and analysis of the real engineering cases of the old and new standards, so as to judge the impact of the new standards on the overall structural cost and the overall construction and installation cost of the house after the partial coefficient in the standards is increased.
CSCEC Aetna (Beijing) Engineering Consulting Co., Ltd.
organized a special discussion meeting on March 20, 2019, and selected four recently reviewed projects in Beijing to carry out horizontal components of one-way slab, two-way slab, simply supported beam and multi span frame beam, as well as high-rise public buildings (frame shear), multi-storey public buildings (frame shear) and pure underground garage (beam slab), high-rise residential (shear wall) and other structures as a whole.
II.
The influence of the partial coefficients of the old and new standards in the unified standard for reliability design of building structures in the design.
1.
Horizontal members (greater influence).
2.
Vertical members (less influence)..
