Precast building | practice and analysis of passive ultra-low energy consumption building based on precast steel structure

In recent years, vigorously developing precast, steel structure and passive ultra-low energy consumption buildings is an important measure for the country to advocate greening and implement energy conservation and emission reduction.

With the passive ultra-low energy consumption building The successful practice of the (passive housing) project in many climate zones in China indicates that it is being paid attention to and recognized by more and more people, and leads the development direction of building energy conservation in China with many advantages such as health, comfort and ultra-low energy consumption.

Precast passive housing integrates the advantages of fast construction speed, energy conservation and environmental protection of precast buildings, and carries out the construction of passive housing Standardized and industrialized design can promote the rapid promotion of passive housing to a certain extent.

However, in order to realize the transformation from the ordinary construction mode of passive house to the industrialized construction mode of assembly, it is necessary to solve the problem of transforming the structural system and envelope system of passive house into the standardized and industrialized precast components of building industrialization.

However, many precast components will form different types of gaps after splicing.

The gaps after splicing and assembly of precast components contradict the high requirements of non thermal bridge and air tightness of passive low-energy buildings.

In view of this, the study takes the precast passive ultra-low energy consumption building as the carrier, analyzes the problems encountered in its construction process, and systematically summarizes the new construction technology of passive building from three aspects: building structure system, enclosure structure selection and precast construction, It plays a guiding role in the construction technology of passive ultra-low energy consumption buildings in the future.

Engineering difficulties and characteristics 1.

Lack of referential cases of construction technology.

Remarkable achievements have been made since the technical cooperation between the science and technology promotion and development center of the Ministry of housing and urban rural development and the German Energy Agency on passive housing in 209.

From the initial project practice in cold areas to the attempts in many climate zones in China, from the initial residential monomer to residential groups, kindergartens, office buildings, hotels and commercial buildings have been successfully built.

However, the construction technology of both residential and public buildings has little reference value in transforming it into assembly system construction.

Therefore, the use of precast system to build passive ultra-low energy consumption buildings is a new measure in this field, which increases the difficulty of construction to a certain extent.

It is difficult to deal with the nodes after the industrialization transformation.

The excellent characteristics of high quality and low energy consumption of the passive house need to be supported by its five core technologies, namely, efficient envelope, no heat bridge technology, efficient air tightness, good door and window system and recyclable fresh air system.

In order to industrialize the passive housing system Standardized precast components (recyclable fresh air system is not within the scope of this study) for the transformation, the basic composition of the passive house and the possibility of transforming the constituent elements of the enclosure structure of the passive house into industrialized components should be analyzed first.

Due to the different positions of the joints of precast slabs, the sealing methods of the joints are also different.

For example, the joints and elevations of two precast slabs at the corner of the building The treatment methods of plate gaps at the relatively central position are different.

Therefore, with the change of building shape and the increase of corners, the difficulty of installation and sealing also increases.

The diversified types of gaps between precast components make it more difficult to deal with air tightness, which is one of the key factors affecting the energy consumption and quality of passive buildings.

In view of the construction system of passive ultra-low energy consumption buildings built by precast technology, it is necessary to assemble multiple precast wallboards into walls, And other components and building structures are fixed by installation and welding.

Therefore, many joints and gaps will be formed after collage and assembly, and many gaps are the key to affecting the air tightness of the house.

In order to avoid the uncontrollability of node gap treatment in the later stage of construction, the connection mode of each node should be comprehensively considered in the architectural construction drawing design of precast passive house, so as to reduce the number of slab joints and through wall openings, In order to facilitate the sealing construction and fault maintenance of the later air tight layer.

The whole construction process of envelope construction follows the principle of green construction within the whole life cycle of green building, strives to achieve green construction control without pollution, dust, low noise and interference to surrounding classrooms, always runs through the characteristics of precast building system, gives full play to its advantages in the construction process, and maximizes water conservation, material conservation, energy conservation and environmental protection, It can achieve good economic benefits.

Before the foundation is fixed, the embedded reinforcement components connected or fixed by the precast wallboard shall be added to ensure the smooth installation of the precast wallboard after the foundation construction.

The specific method is to bind and weld the embedded parts with the foundation beam and pour concrete to make the foundation form a complete reinforced concrete frame.

Before the concrete is solidified, the embedded parts shall be visually leveled until fixed, so as to facilitate the connection with the reserved sleeve of the precast wallboard.

When installing precast stair segments, the stairs shall be lifted to the corresponding position with a crane, and then the technicians shall fix them with the structural system with bolts or steel sheets.

When fixing, adjust the levelness with the help of a level, as shown in Figure 8, to ensure that the direction of the stairs is consistent with the building structure.

Wall panel installation is limited by the manufacturer’s R & D technology, mold type and transportation equipment.

At present, the maximum precast wall panel size that domestic wall panel manufacturers can achieve is 3280mm × 8780mm, it is temporarily impossible to use a whole precast wall panel as a complete facade of the building, which needs to be spliced by several wall panels.

After the precast components are transported to the project site, they shall be marked and numbered in the order of stairs, floors, precast wallboards, balconies, doors and windows according to their types and building parts.