Seismic fortification is not considered in the original design or the seismic fortification requirements are improved; This provision has a long history, and most appraisal standards list it as the situation requiring appraisal, but there are few cases of such operation in actual projects.
From the wording of each general code issued, the design service life is changed to the design service life.
After suffering from disasters or accidents; The situation mentioned here should be generally consistent with the accidental actions in the unified standard for reliability design of building structures (gb50068-2018), including various accidental actions or accidental disasters such as earthquake, fire, flood, explosion and abnormal impact, which should be identified after the disaster.
It needs to continue to be used after reaching the design working life; The design service life in this clause should be the same concept as the design service life referred to in the unified standard for reliability design of building structures (gb50068-2018).
These two specifications are general specifications.
For other cases, such as reconstruction, building displacement and identification before the change of building purpose and service environment, the requirements of gb55021-2021 can be implemented.
After studying the main contents of the general code for appraisal and reinforcement of existing buildings gb55021-2021, it is not difficult to find that compared with the previous two drafts for comments, the final official draft has been greatly changed, and basically systematically answers the problems such as under what circumstances, what appraisal should be carried out and how to carry out appraisal of existing buildings, In fact, the usability and operability have been greatly improved.
4.
Even the anti-seismic appraisal and reinforcement management documents of primary and secondary school buildings issued repeatedly by the State Council have even become legal provisions in the latest regulations on the administration of earthquake resistance of construction projects, but in fact, most competent departments have ignored it, not to mention other types of houses.
The relevant mandatory provisions of the current engineering construction standards shall be abolished at the same time.
3.
Of course, due to the short time, there are still many places worthy of further discussion in the official draft of the specification.
If the relevant provisions in the current engineering construction standards are inconsistent with the specification, the provisions of the specification shall prevail.
It is worth noting whether “design service life” should be changed to “design service life” in subsequent test reports.
5.
2、 Learning experience (I).
How to improve the seismic performance of relevant buildings in an orderly manner is an important issue in front of relevant industry authorities and relevant industry practitioners.
Recently, the Ministry of housing and urban rural development issued an announcement on its official website and issued the official version of the general code for appraisal and reinforcement of existing buildings gb55021-2021.
How can they be coordinated and unified? Lao Chen suggested that the provisions of this paragraph can be implemented with reference to the provisions of Shanghai engineering construction code standard for seismic identification and reinforcement of existing buildings dgj08-81-2021, that is, when adding, inserting or expanding existing buildings, a calculation model should be established according to the structural state after adding, inserting or expanding, Seismic appraisal and seismic design shall be carried out according to the requirements of gb55002-2021 and other current design standards.
Applicable to the appraisal of existing buildings.
1.
Before alteration, expansion, relocation and change of building purpose and use environment; This clause gives various situations that should be identified before changing the existing buildings, but it should be noted that article 1.0.2 of the general code for seismic resistance of buildings and municipal engineering gb55002-2021 also gives corresponding provisions, that is, all kinds of new, expanded and reconstructed buildings and municipal engineering in areas with seismic fortification intensity of 6 or above must be subject to seismic fortification, and the investigation, construction and reconstruction of engineering projects The design, construction, use and maintenance must comply with this specification.
For example, if a house is within the influence of the construction of adjacent construction projects, due to the measures taken by the adjacent construction projects, the impact on the house is very small, and there is no substantial impact on the safety of the house, should the safety appraisal and seismic appraisal of the house be carried out according to the requirements of gb55021-2021? If the seismic capacity of the original house is insufficient after appraisal, how to deal with it? Especially under the premise that the house property right is inconsistent with the adjacent construction projects, it is very easy to cause unnecessary contradictions, and in fact, it has little operability..
The code will be implemented from April 1, 2022.
The actual appraisal contents of post disaster appraisal should be inconsistent with the contents of safety appraisal and seismic appraisal listed in gb55021-2021.
There are serious quality defects or damage, fatigue, deformation, vibration impact and construction impact of adjacent projects; Similar to paragraph 4, in most cases, special appraisal shall be carried out instead of safety appraisal and seismic appraisal.
2.
Article 2.0.2 of the Code stipulates seven situations for the appraisal of existing buildings, which basically cover most of the situations that need to be appraised for existing buildings.
Summary: in early 2019, the Ministry of housing and Urban Rural Development released 38 full-text mandatory engineering construction specifications for housing and urban rural construction on its official website for public comments, and solicited comments from the whole society.
It is a mandatory engineering construction code, and all provisions must be strictly implemented.
Gb55021-2021 only stipulates safety appraisal and seismic appraisal, and does not specify other types of appraisal, which is the deficiency of the code.
However, when the added floor, intercalated floor or expanded area does not exceed 5% of the total construction area of the original house and the newly added area of a single floor does not exceed 10% of the typical floor area of the original house, the seismic appraisal and seismic design can be carried out according to the requirements of gb55021-2021 and other current appraisal standards.