A, the safety of civil engineering structure
Structural safety is the ability of structure to prevent collapse and the most important quality index of structural engineering. The safety of structural engineering mainly depends on the design and construction level of the structure, and it is also related to the correct use (maintenance and inspection) of the structure, and then to the reasonable setting and application of civil engineering regulations and technical standards (specifications, regulations, procedures, etc.). ).
1. Safety setting level of China structural design code. For the design of structural engineering, the safety of structure is mainly reflected in the safety of bearing capacity of structural members, the overall firmness of structure and the durability of structure.
2. Adjust the level of structural safety settings. The safety setting standard in China's structural design code is low. Now it is proposed to re-examine the safety setting level of structures, mainly based on the changes in the objective situation, because the infrastructure construction we are engaged in now should lay the foundation for future modernization and meet the needs of the development of people's production and living standards in the next few decades and hundreds of years, and some civil structures, such as commercial houses, should meet the needs of commodity attributes under the conditions of market economy. For engineers and technicians, the structural safety degree becomes more unpredictable and fuzzy after being expressed by reliability index and false failure probability, and it is not as intuitive and convenient as the safety factor when dealing with the safety problems of specific projects. The reliability method in the current design code is immature and has many fundamental defects. They think that the semi-probability multi-safety factor method is more suitable for the specification, and it does not rule out that the results of reliability analysis can be used as a reference, which should be considered when comprehensively judging the reasonable value of safety factors.
Second, the durability of civil structural engineering
The durability of civil structural engineering is related to the service life of the engineering, that is, the ability of the structure to maintain normal functions during the service life. This normal function includes the safety of the structure and the applicability of the structure, which is more reflected in the applicability.
The concepts of structural durability and service life are inseparable from inspection, maintenance and repair in the use stage, especially for infrastructure projects in the open air and harsh environment. In order to ensure the safety and durability of the structure, some projects should be tested and maintained regularly during the use after completion. There are design specifications and construction specifications for structural engineering in China, but there is no specification on how to use them. Some accidents can be avoided if there is a requirement for regular inspection. In China, the level of construction management and the quality of accident operators are relatively poor, the quality control and quality assurance system is not perfect, and the standards of structural safety and durability are relatively low. There are many hidden dangers in built projects, so it is necessary to determine the requirements of normal use and regular inspection of civil engineering from the legal system. For the safety and quality of civil structural engineering, although the government has stipulated that the units and individuals responsible for design and construction should be responsible for it for life, the implementation of this regulation lacks maneuverability. To reduce structural safety and quality accidents to a minimum, we should also give priority to prevention and find problems in time through routine testing.
At present, a large number of civil engineering projects in China need to be diagnosed and treated because they have entered the aging stage, and a large number of illegal projects need to be evaluated. Many projects have diseases that need to be diagnosed and reinforced. Many teams engaged in civil engineering diagnosis, treatment and reinforcement have emerged in various places, and there is a trend of vigorous development as a new industry. It is important to treat problems and diseases in the future, but we should put more emphasis on prevention. For the detection and evaluation of civil engineering in service, it is necessary to establish corresponding laws and standards, have the registration of employees and the qualification certification system of institutions, and standardize the management system.
Judging from the state's investment in public engineering construction and the requirements for engineering design, it is necessary to demonstrate the whole life of the project, that is, the whole life expenditure. Only paying attention to the one-time investment expenditure of the project construction and seldom considering the long-term cost of normal maintenance and repair after the completion of the project may not only damage the service life and normal use function of the project, but also be uneconomical to calculate the general ledger economically. Although China is a developing country, a large number of projects are being built now, but a large number of projects built in the past have been prematurely aging. In addition, since the 1990s, the traffic volume has soared, the overload is serious, the previous design standards are low, and the maintenance problems of roads and bridges are very prominent. Because the maintenance cost can not be guaranteed, it will cause hidden dangers of engineering safety, and more overhaul costs will be needed in the future.
Third, the role and management of technical specifications
For a long time, influenced by the planned economic system, we often regard technical specifications as laws and the specific provisions and requirements of specifications as legal provisions. Technical specifications or regulations, like technical documents such as technical regulations, technical requirements, construction methods and guidelines, are technical standards and have no legal effect in themselves. Only when all parties (owners, design and construction enterprises) agree to take it as the basis of design and construction, and take the contract as the basis, can it be used as the basis of legal arbitration. Legalizing and enforcing technical problems is not conducive to technological progress and creativity, but is easy to become an excuse to shirk responsibility. Of course, from the overall interests of the country and the public, government departments need to put forward the minimum requirements that civil engineering design and construction must meet, and formulate corresponding laws and regulations on major principles such as safety and environmental protection, but laws and regulations generally do not need to provide specific technical ways and methods to achieve these requirements, which is the task of technical standards. The government can also recognize or approve the use of some important technical specifications or some of their contents in principle.
Civil engineering has a strong personality, which requires engineers and technicians to solve design and construction problems according to specific characteristics. Therefore, as a technical standard, the specification should emphasize its guidance rather than mandatory. If the standard provisions are regarded as legal provisions in a general sense, it may limit the initiative and creativity of designers and constructors and hinder the application of new technologies. The biggest gap between China's civil engineering and foreign countries in structural design lies in the innovation of scheme and technology, which is not unrelated to the tendency of overemphasizing the legal status of norms and thus forming the so-called "structural design is norms plus calculation". China's technical specifications tend to imitate the law in writing style, and rarely mention that users need to pay attention to some possible shortcomings of the specifications or allow and encourage users to find another way on some issues. It is illegal to replace outdated or even harmful technical clauses in the specification in design and construction. On the contrary, as long as you follow the rules, even if there is an accident, you can not bear legal responsibility. This objectively reduces the requirements for the professional skills and responsibilities of engineers and technicians, which is not conducive to improving the quality of construction enterprises and employees in China and participating in future international competition.
In order to eliminate these negative effects and stop using the loopholes in the standard provisions to cut corners, it is necessary to establish such an understanding and make provisions that observing the standard provisions does not mean that legal responsibility can be exempted. Some foreign norms stipulate this. It is not an effective way to solve the recurring engineering accidents by constantly strengthening the compulsion of technical specifications. At present, the relevant authorities have taken out some provisions in the Code for Design of Building Structures, which are clearly listed as mandatory provisions. At the same time, it is stipulated that the design completed by each design unit must be reviewed by the relevant departments or other enterprises and institutions authorized by them. The main content of the review is to control the requirements of mandatory provisions in the specification, and its task is similar to law enforcement; Whether this is wise or not seems debatable.
The frequent occurrence of civil engineering accidents in China mainly lies in poor management, especially corruption in management; Secondly, the quality of construction operators is low, which is difficult to solve in a short time; Too much emphasis on the status and role of norms, failure to establish a complete standard system supporting norms, such as the lack of more detailed and specific technical documents such as guidelines and construction methods, can be used to guide and standardize each specific link of design and construction, and there is a certain relationship. From the design point of view, the accident is not mainly due to the failure to comply with the mandatory provisions of the code, but to the wrong scheme or neglect of the main design conditions; There are also some projects that fail because of low design standards, insufficient durability and lack of proper routine tests during use. In fact, it is the easiest to meet the requirements of the mandatory provisions in the design code, so it seems unnecessary to ask professionals to review it. Important engineering design should require a comprehensive audit by professional units, and its main points should also be on the principles of structural scheme, structural method and calculation and analysis. The mandatory provisions extracted from the national Code for Structural Design are inevitably scattered, and the provisions of individual provisions may not be suitable for the specific characteristics of certain areas and projects, but cause trouble.
China has a vast territory, unbalanced economic development, great disparity in technical strength and different environmental conditions. Objectively speaking, it is required that the specification can give designers more flexibility and less compulsion, so as to solve problems better under the guidance of the specification and according to the characteristics and specific conditions of the project. In short, in terms of norms and standards, we should get rid of the tendency of excessively demanding unity, giving less consideration to individuality and lacking the flexibility of seeking truth from facts left over from the planned economy era. To advocate and encourage provinces and cities to compile local codes, there may be different standards for the safety and durability of the project. For example, Shanghai, Beijing and Guangzhou are higher, and they are treated differently in terms of earthquake resistance and disaster prevention requirements. The more detailed the national norms are, the worse the applicability may become, and the more confusion may be caused; This is especially true for specifications such as geotechnical engineering.
The more mandatory the technical standards are, the heavier the responsibility of the relevant government departments on specific technical issues, which should not be the responsibility of government departments. The requirements in the code are the minimum requirements, and the level of security settings that the government needs to intervene should also be the minimum requirements for ensuring public safety. For the seismic design of civil structures, the relevant government departments still stipulate that no department or individual may raise the seismic fortification standards without authorization (anti-document No.586). In fact, if the seismic fortification intensity of commercial housing is increased by 1 degree, the seismic capacity can be increased by about 1 time, and the increased housing cost is quite limited, which may be only a fraction of the indoor decoration cost of many urban residents. This provision of the government is tantamount to restricting residents from buying houses with the lowest seismic safety and quality standards. If the earthquake causes damage, how can the relevant departments explain it?
For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd