CN106193288A - A kind of precast concrete node pouring ECC layer - Google Patents

Abstract

The invention discloses a prefabricated concrete node for pouring an ECC layer, comprising square steel pipes, prefabricated beams, and prefabricated columns; the prefabricated beams and prefabricated columns are coaxial and parallel to each other and arranged on the outer ring of the steel skeleton, and the square steel pipes are The shaft is built into the prefabricated column longitudinally, and steel plates 1 are respectively arranged on the longitudinal end faces of both sides of the square steel pipe. The area formed between the sides and the prefabricated columns, between the steel plates 2, and between the steel plates 1 constitutes the main pouring area, and the engineering cement-based composite material ECC layer is poured in the main pouring area. The prefabricated concrete node for pouring the ECC layer of the present invention has the advantages of fast construction speed, convenient node connection, high strength, more guaranteed quality control, etc., and has more safety, applicability, durability and economy.

Description

A kind of prefabricated concrete node for pouring ECC layer

technical field

The invention relates to a concrete node, in particular to a prefabricated concrete node for pouring an ECC layer.

Background technique

At present, rectangular concrete-filled steel tube composite structures have been widely used in construction projects. The technology of rectangular steel-filled concrete-filled composite structures has been greatly developed in recent years. Rectangular steel-filled concrete-filled composite structures have been widely used in engineering because of their high bearing capacity and good ductility. With the continuous emergence of super high-rise and long-span building structures, rectangular concrete-filled steel tube connection points have become one of the important contents in the design of building structures. The connection points directly affect the overall performance of the structure under load-bearing conditions and the load-bearing performance of the connected structures. Therefore, the performance of the connected node structure cannot be ignored.

At present in our country, the research and application of engineering cement-based composite materials ECC (Engineered Cementitious Composites) is still less, and the most used in actual engineering is still ordinary concrete.

Contents of the invention

In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a prefabricated concrete node with higher safety, applicability, durability and economy.

In order to achieve the above object, the present invention adopts the following technical solutions:

A prefabricated concrete node for pouring an ECC layer, comprising square steel pipes, prefabricated beams, and prefabricated columns; the prefabricated beams and prefabricated columns are coaxial and parallel to each other and arranged on the outer ring of the steel skeleton, and the square steel pipes are The shaft is built into the prefabricated column longitudinally, and steel plates 1 are respectively arranged on the longitudinal end faces of both sides of the square steel pipe. The transverse ends of the steel plates 1 are connected to the steel plates 2 built in the prefabricated beams. In the longitudinal plane, the area formed between the outer side of the square steel pipe and the prefabricated columns, between the steel plates 2 and between the steel plates 1 constitutes the main pouring area, and the engineering cement-based composite material ECC layer is poured in the main pouring area.

The square steel pipe is set in the prefabricated column node, connecting the steel plate 1 and the steel plate 2, which enhances the overall performance and strength of the node.

Steel plate 1 and steel plate 2 are used for connection of prefabricated column joints and prefabricated beam joints, and bear tension/compression stress.

The outer ring of the above-mentioned square steel pipe is provided with a transverse reinforcement skeleton.

The reinforced skeleton constitutes a structural entity and strengthens the overall strength of prefabricated beams and prefabricated columns; stirrups increase the shear stress of oblique sections, and connect and connect the main reinforcements to act together.

The above-mentioned steel plate 2 is fixedly connected with the two inner longitudinal surfaces of the prefabricated beam.

A concrete layer is poured in the square steel pipe.

The post-casting concrete layer or the engineering cement-based composite material ECC layer in the above-mentioned prefabricated beam.

The post-casting concrete layer or engineering cement-based composite material ECC layer in the above-mentioned prefabricated column.

The above-mentioned steel plate 1 and steel plate 2 are connected by bolts.

The steel plate 1 and the steel plate 2 are tightly combined by bolts, and the force on the steel plate 2 is transmitted to the steel plate 1 through the friction surface, that is, the force on the prefabricated beam is transmitted to the prefabricated column. The bolt connection strengthens the connection strength between the steel plates, and after the prefabricated beam is damaged, it is convenient to repair or replace the prefabricated beam without involving the prefabricated column, maintaining the overall safety.

The benefit of the present invention is that: the beam column of the prefabricated concrete node of the pouring ECC layer adopts a built-in steel structure, and the built-in steel plate is connected by high-strength bolts. Compared with the traditional connection method, it has the advantages of fast construction speed, convenient node connection, and high strength High quality, more secure quality control and other advantages, and more safety, applicability, durability and economy.

Through the improvement of the structure, under the action of cyclic load, the final damage point of the precast concrete joint is shifted from the core area of the joint to the end of the steel plate in the precast beam and the bolt connection part, and the damage position is moved outward, which is in line with the principle of "strong column and weak beam". .

The prefabricated concrete joint maintains good ductility while improving the bearing capacity, and the engineering cement-based composite material ECC is used for pouring in the main pouring area of the joint, and square steel pipes are pre-buried to strengthen the joint area and improve the joint strength. The energy consumption is in line with the design principle of "strong nodes, weak components".

The use of engineering cement-based composite material ECC improves the seismic performance and damage resistance of the joints, thereby reducing the cost of repairing joints after the earthquake, and the configuration of ECC can use industrial waste fly ash to replace about 50% of the joints. Cement clinker realizes waste recycling with lower cost.

In addition, the good compactness of ECC effectively prevents the penetration of harmful substances into the interior of the component material, improves the durability of the component, and prolongs the service life of the structure.

Description of drawings

Fig. 1 is a side view of a schematic structural diagram of a prefabricated concrete node for pouring an ECC layer according to the present invention.

Fig. 2 is a top view of a structural schematic diagram of a prefabricated concrete node for pouring an ECC layer according to the present invention.

Fig. 3 is a perspective view of a structural schematic diagram of a prefabricated concrete node for pouring an ECC layer according to the present invention.

Fig. 4 is an appearance diagram of a structural schematic diagram of a prefabricated concrete node for pouring an ECC layer according to the present invention.

Figure 5 is the hysteretic curve of the cast-in-place concrete joint simulated by the finite element software ABAQUS.

Figure 6 is the hysteretic curve of the precast concrete joint simulated by the finite element software ABAQUS.

Fig. 7 is the load-displacement skeleton curve of the poured ECC layer and the poured concrete C60 layer in the main pouring area of the precast concrete joint simulated by the finite element software ABAQUS.

The meanings of the marks in the attached drawings are as follows: 1. square steel pipe, 2. prefabricated column, 3. prefabricated beam, 4. steel plate 1, 5, steel plate 2, 6. stirrup, 7. steel skeleton.

detailed description

The present invention will be specifically introduced below in conjunction with the accompanying drawings and specific embodiments.

A prefabricated concrete node, including square 1 steel pipe, 3 prefabricated beams, 2 prefabricated columns; 3 prefabricated beams and 2 prefabricated columns are a number of 6 stirrups coaxial and parallel to each other and arranged on the outer ring of 7 steel bar skeletons, 1 square steel pipe with The shaft is built in 2 prefabricated columns longitudinally, and 4 steel plates 1 are respectively arranged on the longitudinal end faces of both sides of 1 square steel pipe, and the transverse ends of 4 steel plates 1 are connected by bolts to 5 steel plates 2 built in prefabricated beam 3, 4 steel plates 1 and 5 steel plates 2 After being connected on the same longitudinal plane, the area composed of the outer side of the 1 square steel pipe and the 2 prefabricated columns, the 5 steel plates 2, and the 4 steel plates 1 constitutes the main pouring area, and the engineering cement base is poured in the main pouring area. Composite ECC layer.

The outer ring of the 1-square steel pipe is provided with a horizontal 7-bar skeleton.

5. The two inner longitudinal surfaces of the steel plate 2 and 3. the prefabricated beam are fixedly connected.

Concrete layer is poured in 1 square steel pipe.

3 prefabricated beams and 2 prefabricated columns post-cast concrete layer or engineered cement-based composite material ECC layer.

Under the action of cyclic load, the final failure of the cast-in-place concrete joint is the core area of the joint, while the damage of the precast concrete joint is concentrated at the end of the steel plate and the bolt connection part of the 3 prefabricated beams. It is in line with the principle of "strong columns and weak beams".

Figure 5 and Figure 6 are the hysteretic curves of the cast-in-place concrete joints and precast concrete joints simulated by the finite element software ABAQUS respectively. 28.22%, the equivalent damping coefficient increased by 58.86%, and the average value of the displacement ductility coefficients of the two is greater than 3, which meets the requirements of the reinforced concrete structure displacement ductility coefficient greater than 2.57.

It shows that the precast concrete joints maintain good ductility while improving the bearing capacity, and the engineering cement-based composite material ECC is used for pouring in the post-casting area of the joints, and the square steel pipe 1 is pre-buried to strengthen the joint area and improve The energy consumption of the nodes is guaranteed, which is in line with the design principle of "strong nodes, weak components".

The tensile damage factors of the poured concrete C60 layer and the poured ECC layer in the main pouring area of the precast concrete joints were simulated by the finite element software ABAQUS, and the failure modes of the precast concrete joints of the poured ECC layer and the poured concrete C60 layer in the main pouring area were similar, and the damages were both major Concentrated on the bolt connection position, the pouring surface and the end of the steel plate in the beam. When the pouring material is concrete C60, the damage degree of the joints is obviously more serious than that of the cement-based composite material ECC in the pouring project.

Fig. 7 is the load-displacement skeleton curve of the poured ECC layer and the poured concrete C60 layer in the main pouring area of the precast concrete joint simulated by the finite element software ABAQUS.

Table 1 Comparison of node feature quantities between pouring material ECC layer and concrete C60 layer in the main pouring area:

Characteristic values of specimen with different late-pouringmaterial

Table 1

It can be seen from Fig. 7 that the initial stiffness of the joint skeleton curve of poured concrete C60 is slightly larger than that of poured ECC joints. This is because the matrix of engineering cement-based composite ECC does not contain coarse Due to the tensile strain-hardening effect, the particle size and content of the sand in the matrix are also limited, which reduces the stiffness of the ECC to a certain extent. In addition, due to the incorporation of PVA fibers, the porosity of the matrix increases. The homogeneity is reduced, which also causes the elastic modulus of ECC to be lower than that of ordinary concrete, so the initial stiffness of the skeleton curve of ECC joints is lower than that of concrete C60 joints.

In addition, comparing the skeleton curves of ECC joints and concrete C60 joints, it can be seen that although the maximum load that the two joints can bear is not much different, there is a significant difference in deformation capacity. Table 1 lists the main characteristics of the joints under the two pouring materials It can be seen that the yield displacement and ultimate displacement of ECC joints are larger than that of concrete C60 joints, and its average displacement ductility coefficient is 8.16% higher than that of concrete C60 joints, and after reaching the peak load, the skeleton curve of ECC joints decreases Slower, this is because when the node curve enters the descending section, as the cracks continue to expand, the crack resistance effect of the PVA fiber in ECC begins to be obvious, causing the load curve to decline slowly, and its peak strain is significantly greater than that of ordinary concrete. Among them, the high-strength The ultimate tensile strain of the ECC can reach about 3%, which shows that PVA fiber can significantly improve the plastic deformation capacity of the ECC matrix, and due to the increase in the plastic deformation capacity, the energy dissipation performance of the nodes is also improved accordingly, as can be seen from Table 1 , compared with concrete C60 joints, the equivalent damping coefficient of ECC joints increased by 21.26%.

Therefore, when the main pouring area of precast concrete joints adopts engineering cement-based composite material ECC, the seismic performance and damage resistance of the joints are improved, thereby reducing the cost of repairing joints after the earthquake, and when ECC is configured, Industrial waste fly ash can be used to replace about 50% of cement clinker to realize waste recycling. In addition, the compactness of ECC is very good. Under normal use conditions, the surface of components can not crack for a long time, effectively preventing harmful substances from flowing into Penetration inside the component material improves the durability of the component, which in turn prolongs the service life of the structure.

Considering the three elements of society, economy and environment, the use of ECC materials has a cost advantage of about 37% compared with ordinary concrete. Therefore, for the node form in the present invention, the use of ECC as the pouring material in the main pouring area is in line with safety and applicability , durability and economical structural design functional requirements.

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the above-mentioned embodiments do not limit the present invention in any form, and all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (7)

1. the precast concrete node pouring ECC layer, it is characterised in that include square steel tube, precast beam, prefabricated post；Described Precast beam and prefabricated post are the outer ring being arranged on framework of steel reinforcement that some stirrups are coaxial and are parallel to each other, and described square steel tube is coaxially indulged To being built in prefabricated post, the both sides longitudinal terminal surface of described square steel tube being respectively equipped with steel plate 1, the transverse end of described steel plate 1 connects Being built in after the steel plate 2 of precast beam, described steel plate 1 and steel plate 2 connect and be in same longitudinal surface, described square steel tube lateral surface is with pre- Between post processed, between steel plate 2, between steel plate 1, the region of composition constitutes main casting area, pours engineering in described main casting area Cement-base composite material ECC layer.

A kind of precast concrete node pouring ECC layer the most according to claim 1, it is characterised in that described square steel tube Outer ring be provided with transverse steel skeleton.

A kind of precast concrete node pouring ECC layer the most according to claim 1, it is characterised in that described steel plate 2 with Inside the two of precast beam, longitudinal surface is fixing connects.

A kind of precast concrete node pouring ECC layer the most according to claim 1, it is characterised in that described square steel tube Interior casting concrete layer.

A kind of precast concrete node pouring ECC layer the most according to claim 1, it is characterised in that described precast beam Interior after-pouring concrete layer or engineered cementitious based composites ECC layer.

A kind of precast concrete node pouring ECC layer the most according to claim 1, it is characterised in that described prefabricated post Interior after-pouring concrete layer or engineered cementitious based composites ECC layer.

A kind of precast concrete node pouring ECC layer the most according to claim 1, it is characterised in that described steel plate 1 He Steel plate 2 is bolted.