1 internet of things technology
The Internet of Things is a network that realizes intelligent identification, location, tracking, monitoring and management by exchanging and communicating information through information-aware devices according to agreed protocols [3]. As far as the current level of scientific and technological development is concerned, it is more appropriate to use RFID as the sensing device of the Internet of Things in construction project management. RFID is radio frequency identification, which is a kind of wireless information sensing equipment, commonly known as electronic tag. At present, the most advanced RFID is made of heat-sensitive and light-sensitive materials, with intelligent components as the core, storing information electronically, connecting objects with the Internet, enabling objects to actively perceive and feedback information, realizing mass storage and achieving the purpose of intelligent identification and management. According to statistics, the use of RFID can help reduce the level of theft and inventory by 25%, and save labor costs, because there is no need to manually check the bar code of incoming goods.
2 Internet of Things technology in the construction of project management platform application
The Internet of Things technology is based on perception layer, transport layer and application layer, which realizes the intelligentization of construction project management. Construction engineering management involves a large amount of information, a wide range and a lot of tedious, and the whole process detection of building materials involves a lot of time and space information. For the whole life detection of a building, it is necessary to arrange several to a dozen RFID devices on each main load-bearing member of the building. Therefore, building engineering information management needs a large number of sensors and a huge data storage and processing system. The emergence of cloud computing makes the price of storing and processing data drop sharply, and the price of sensors drops rapidly, which makes it possible to use a large number of sensors in construction projects and realize intelligent management of construction projects.
2. 1 perception layer
Perceptual layer refers to collecting information through RFID, making objects carry their own information and realizing the update and accumulation of flowing data [4]. In the whole process of monitoring and management of building materials, the information collected by the perception layer mainly includes: product information of building materials, logistics information chain formed during transportation, handler information and so on. In the whole life cycle detection of buildings, the information collected by the sensing layer mainly involves the design information, acceptance and in-service detection information of main load-bearing components.
2.2 transport layer
Transport layer is a network transmission technology, which is used to solve the problems of network access, transmission, conversion and positioning in the network layer. Because WLAN has many advantages, such as high mobility, strong anti-interference, strong security performance, strong expansibility, easy network construction, convenient management and so on, and the construction project has a large amount of information, and the construction environment is complex, in order to realize the whole life cycle detection of buildings, we should try our best to use more advanced technical means as the transmission layer to facilitate the future system upgrade. According to the current level of science and technology, WLAN can be used as a transmission platform for construction project management.
2.3 Application layer
Application layer is the core architecture to show the great value of Internet of Things applications. It aims to realize information analysis, processing, control and decision-making, and complete specific intelligent applications and services, so as to realize the perception between things, people and things and play an intelligent role. In construction projects, the application layer is required to have the functions of mass storage, data management and intelligent analysis. Therefore, cloud computing technology should be used as an application layer and gathered on high-performance computers everywhere [5] to provide a service platform for the application of the Internet of Things in construction project management. The elements of the application of Internet of Things in construction project management are shown in figure 1.
3. Application mode of Internet of Things in construction project management
3. 1 Whole process monitoring and management of building materials
The whole process monitoring and management of building materials refers to embedding RFID in each unit material to record the product information of the materials when they leave the factory. In transportation, the logistics information chain is formed by time and space information until the building materials enter the site and put into use. Managers can clearly understand all the information of this batch of building materials by scanning RFID. When entering the site, the management personnel who receive the materials should make a preliminary evaluation of the product quality and input the inspection results into RFID to further ensure the quality of the materials entering the site. When there is a problem with the building materials of a certain unit, the responsible person can be identified by scanning RFID, which can reduce the responsibility shirking and improve the management enthusiasm of managers. The whole process monitoring and management information input of specific building materials is shown in Figure 2. Among them, the place of use refers to which part of the building materials are specifically used to facilitate future management. Product information includes product attributes, quality grade, production date, manufacturer, etc.
3.2 Building life cycle detection
The concrete method of life cycle detection of construction project is to put RFID with stress sensing function into main load-bearing components, such as frame beams and columns, without affecting the structural function of components. According to the stress requirements of components, RFID should be arranged in places with large tensile and compressive stress, and the corresponding basic information of components, such as design information, construction unit information, construction unit information, etc. , should be entered. With the progress of the project, new information is continuously input: the acceptance status of each component and the information of inspectors are input during acceptance, and each component is tested in real time after it is put into use, and the stress of each component is recorded, so as to eliminate potential safety hazards and rationalize the service life of the building.
3.2. 1 Enter basic information
The input of basic information serves the subsequent acceptance, safety assessment and reasonable life assessment of buildings. The basic information mainly includes the information of project construction unit, design information and construction unit. This link is the premise of building life cycle detection. The more detailed and organized the input information, the more labor-saving the follow-up work will be. The information of the project construction unit includes the name of the project, the address of the construction site and the name of the construction unit. , input when needed in the future. Design information includes drawing number, component number, concrete grade, reinforcement information, section size, design unit, stress design limit value of components, etc. Main load-bearing members. The information of the construction unit mainly includes the name of the construction unit, the person in charge of the project, the management personnel in a specific area, etc. Entering these information can speed up the information circulation between the management personnel in the construction site, clarify the responsible person, and improve the work efficiency and project quality.
3.2.2 Improve the acceptance efficiency
When the project is accepted, the supervisor first enters the acceptance date, the acceptance unit and the personal data of the supervisor in RFID. Scan RFID during acceptance, check component design information with field inspection results, and record the quality acceptance results of components. This can save a lot of time to consult drawings, reduce the quality problems caused by the quality of managers and other reasons, and the on-site acceptance results are well documented and the acceptance quality is guaranteed.
3.2.3 Reduce potential safety hazards in use.
After the project is completed and put into use, RFID with stress sensing function can realize the whole life cycle monitoring of the building. When the stress of the component exceeds the allowable value, it will give an alarm, so as to find the problematic component in time, take maintenance measures as soon as possible, realize preventive and targeted maintenance, and reinforce the building before the safety problem occurs. This means zero unplanned downtime instead of wasting a lot of time on daily maintenance, that is, if there are no emergencies, there will be no safety problems in the building. In daily operation, possible safety hazards can be handled in advance through monitoring, which greatly improves the safety performance of buildings and saves the detection time of the current detection department. Because some tests need to partially destroy buildings, RFID is used to avoid unnecessary damage. Because it can solve the security risks in time, RFID is used to indirectly improve the service life of buildings.
3.2.4 Rational evaluation of building life
When the building reaches the designed service life, it is necessary to collect all-round data, that is, to carry out a physical examination of the building, and analyze whether the building can continue to be used or what maintenance measures need to be taken according to the detection data collected by RFID and the information previously stored in RFID, so as to reasonably extend the service life of the building. In recent years, there are more and more short-lived buildings in China. Many buildings can still be used normally after reaching the designed service life, and some can continue to be used with minor repairs. In today's increasingly tight resources, it is undoubtedly a waste of resources to artificially stipulate the service life of buildings, and repeated construction causes a lot of waste of manpower and material resources. Using RFID can rationalize the service life of buildings and maximize the economic benefits of buildings.
4 conclusion
The emergence of the Internet of Things has brought great changes to people's lives. Applying the Internet of Things to construction project management is likely to be an important means to change the management mode of construction projects. In this paper, two models, the whole process monitoring and management of building materials and the whole life cycle detection of buildings, are initially designed, hoping to provide reference for the application of Internet of Things in intelligent management of building engineering.
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