Fabricated prestressed concrete beam-slab composite floor system

Abstract

The invention discloses an assembly type prestressed concrete beam-slab composite floor system which comprises a prestressed concrete composite floor slab, a prestressed steel-concrete composite beam and a steel pipe concrete column. The composite floor slab is prefabricated through a pre-tensioning method, the slab end is provided with a thickness reduction section, and multiple types of steel bars extend out; the laminated beam comprises a factory prefabricated layer and a field laminated layer, and first profile steel connecting pieces are embedded in the two ends of the laminated beam. The steel pipe of the concrete filled steel tubular column segment is provided with an extending second profile steel connecting piece. The longitudinal stress bars and the prestressed bars of the plate-plate node extend into a laminated layer to form a reinforcing mesh, the transverse distribution bars of the plate-plate node are connected in a staggered manner on a post-cast strip, and beam-column node profile steel connecting pieces are connected through high-strength bolt shear resistance and flange plate welding bending resistance; and all nodes are filled with superimposed layer concrete through one-time pouring. The integrality and the mechanical property of the floor system are improved, construction is efficient, and the method is suitable for large-span and heavy-load buildings.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fabricated concrete frame structure and steel-concrete composite structure, and particularly relates to a fabricated prestressed concrete beam-slab composite floor system. BACKGROUND

[0002] In the fabricated concrete building structure system, the fabricated prestressed concrete beam-slab composite floor system is a core component affecting the overall performance of the building. The system includes three major nodes of the connection of the prefabricated floor slab and the composite beam, the connection of the prefabricated floor slab and the adjacent component (beam or floor slab), and the connection of the composite beam and the concrete-filled steel tubular column, which directly determines the integrity, seismic performance, construction efficiency and durability of the structure.

[0003] However, the existing technology has many technical bottlenecks in the application of the system: The plate-beam joint is weak in bonding and insufficient in integrity: The traditional prefabricated floor slab (such as prestressed hollow slab and double T slab) is mostly simply placed on the beam body or beam lug, only the top negative bending moment reinforcement is connected with the post-poured concrete of the beam, and the prestressed reinforcement at the bottom of the slab is often truncated or simply anchored at the end of the slab without participating in the stress of the joint. This construction causes limited bonding contact area of the steel and concrete, insufficient shear bearing capacity, bending stiffness and negative bending moment transmission capacity of the joint, and the interface is easy to become a weak link of the structure, which weakens the overall stiffness of the floor.

[0004] The connection between the plate side and the adjacent component is poor in reliability: The lateral seams of adjacent prefabricated floor slabs mostly use simple splicing or narrow post-poured strip design, which only relies on a small amount of distributed reinforcement lap joint. When the post-poured concrete is filled, voids are easy to appear due to the narrow space, resulting in low load transmission efficiency between the slabs and unable to form a continuous overall floor. When the side edge of the floor slab is connected with the beam, the length of the transverse distribution reinforcement extending into the beam body and the anchoring mode are unreasonable, which further reduces the cooperative stress capacity of the joint.

[0005] The stiffness of the beam-column joint suddenly changes and the stress concentration is significant: When the traditional prestressed steel reinforced concrete composite beam is connected with the concrete-filled steel tubular column, the longitudinal steel in the beam suddenly terminates at the section height of the beam end, which causes the stiffness of the beam to change sharply from the pure concrete area to the steel area, the stress concentration in the joint core area is serious, the ductility deformation capacity and energy dissipation performance are poor, and the seismic performance cannot meet the demand of high intensity area. Moreover, the anchoring of the longitudinal reinforcement at the beam end needs to be densely holed or bent, which is complex in construction and difficult to construct, and is easy to cause joint failure due to construction quality problems.

[0006] The construction efficiency and quality controllability are low: The combined joint structure of the full prefabricated slab and the composite beam and the composite beam and the column is complex, the risk of steel collision is high, the space for site pouring is narrow, and the concrete is difficult to fill densely.

[0007] Although the existing improved technologies (such as setting shear key grooves, adding U-shaped bars and adopting wet connections) try to solve some problems, there are still defects such as complex structure, large material consumption, insufficient utilization of prestress advantages or uneven transition of beam-column joint stiffness. Therefore, an assembly type prestressed concrete beam-slab composite floor system which takes into account the structural high performance, construction convenience and economy and can simultaneously optimize the structure of three nodes is urgently needed. SUMMARY

[0008] In view of the above problems, the application provides an assembly type prestressed concrete beam-slab composite floor system which comprehensively innovates and optimizes the structure design, joint connection and construction process to solve many problems in the prior art. The optimization in the structure design reduces unnecessary waste of materials, and the reasonable reinforcement and structural design enables the materials to fully exert their mechanical properties, thereby reducing the material cost. In terms of joint connection, the complex structure and a large number of connecting pieces are avoided, the construction process is simplified, and the labor and material costs are reduced. In terms of construction process, factory prefabrication improves the production efficiency, reduces the cost and time cost of on-site construction, and also reduces the additional cost caused by construction quality problems.

[0009] To achieve the above-mentioned purpose, the application discloses an assembly type prestressed concrete beam-slab composite floor system, which comprises a prestressed concrete composite floor, a prestressed steel-concrete composite beam and a steel pipe concrete column, and the key lies in that: The prestressed concrete composite floor comprises a plate body and multiple types of steel bars arranged therein; the plate body is integrally formed by one-time casting by using the pretensioning method, and a gap exists in the upper part of the plate end of the prestressed steel-concrete composite beam to form a thickness reduction section; and the multiple types of steel bars all extend out of the plate edge; The prestressed steel-concrete composite beam comprises a beam body and a beam skeleton arranged therein; the beam body is composed of a prefabricated layer prefabricated in a factory and a composite layer cast on site, and a first type of steel connecting piece is embeddedly installed at both ends of the beam body; the prefabricated layer is integrally formed by one-time casting by using the pretensioning method; and the height of the composite layer is consistent with the thickness of the non-thinning section of the plate body; The steel pipe concrete column comprises a segmented steel pipe and a column body concrete casted inside; the segmented steel pipe is further provided with a second type of steel connecting piece extending out of the pipe wall thereof; Among them, at the connecting joint between the plate end of the prestressed concrete composite floor and the prestressed steel-concrete composite beam, the plate body is placed on the prefabricated layer, the longitudinal stress bars and the prestressed bars in the multiple types of steel bars all extend to the composite layer to jointly form a dense steel mesh with the beam skeleton of the composite layer; and the post-cast concrete of the composite layer fills the joint area and wraps all the steel bars extending into the steel pipe. At the connecting joint between the side of the prestressed concrete composite floor and the prestressed steel-concrete composite beam, the transverse distribution bars in the multi-type steel bars extend into the reserved post-cast zone between the two, and are wrapped by the post-cast concrete of the composite layer along with the pouring of the composite layer; At the connecting joint between two adjacent prestressed concrete composite floors, the transverse distribution bars in the multi-type steel bars of the two are connected in layers and staggered in the reserved post-cast zone of the lateral joint, and the post-cast concrete of the composite layer wraps all the connecting steel bars along with the pouring of the composite layer; At the connecting joint between the prestressed steel-concrete composite beam and the concrete-filled steel tube column, the first web plate of the first type steel connecting piece and the second web plate of the second type steel connecting piece are aligned with each other, and high-strength bolts are used for shear connection; the upper and lower first flange plates of the first type steel connecting piece are aligned with the upper and lower second flange plates of the second type steel connecting piece, respectively, and then welded to form a bending-resistant connection; and the exposed parts of the first type steel connecting piece and the second type steel connecting piece are wrapped by the post-cast concrete of the composite layer along with the pouring of the composite layer.

[0010] Further, the bonding surface between the thickness reduction section and the post-cast concrete of the composite layer is provided as a rough surface, and a plate end reinforcing bar acting on the post-cast concrete of the composite layer is further arranged on the thickness reduction section; a post-cast zone reinforcing bar acting on the post-cast concrete of the composite layer is further arranged in the reserved post-cast zone between the lateral joint of the two adjacent prestressed concrete composite floors and / or the reserved post-cast zone between the side of the prestressed concrete composite floor and the prestressed steel-concrete composite beam.

[0011] Further, the longitudinal load-bearing bars are composed of a top plate longitudinal bar and a bottom plate longitudinal bar, and an upper layer of transverse distribution bars and a lower layer of transverse distribution bars are arranged between the two; the top plate longitudinal bar uses a negative bending moment bar, and the bottom plate longitudinal bar uses a prestressed bar.

[0012] Further, the first type steel connecting piece includes a pair of non-continuous embedded beam body end portions, first flange plates receiving the upper and lower beam longitudinal bars of the beam skeleton, and a first web plate arranged between the two; a section of the first web plate embedded in the beam body end portion extends towards the beam span direction and forms an extension section with gradually decreasing cross-sectional height; the extension section is used to build a transition area with continuously and smoothly changing bending stiffness in the beam body; the second type steel connecting piece includes a pair of transverse stiffening plates with grouting holes arranged in the segmented steel tube, and a second web plate arranged between the two; the second web plate extends out of the segmented steel tube and is aligned and connected with the first web plate; at the upper and lower plate edges of the section of the second web plate extending out of the segmented steel tube, second flange plates receiving the segmented steel tube are respectively arranged; the upper and lower second flange plates are respectively aligned and connected with the upper and lower first flange plates.

[0013] Further, at least part of the cross-sectional height of the extension section changes linearly or non-linearly.

[0014] Further, the overall cross-section height of the extension section varies linearly, and the upper and lower plate edges are inclined and close to each other to form a wedge-shaped structure.

[0015] Further, the combined floor system is constructed according to the following steps: S1. Factory prefabrication: prefabricate the prestressed concrete composite floor to form a thickness-thinned section and make multiple types of steel bars extend by a predetermined length; prefabricate the prefabricated layer of the prestressed steel-concrete composite beam to install the first type of steel connecting piece and build the beam skeleton; prefabricate the segmental steel pipe of the steel pipe concrete column to install the second type of steel connecting piece; S2. On-site installation: hoist the segmental steel pipe, pour the column body concrete, and ensure the compactness through the grouting holes on the transverse stiffening plate; hoist the prestressed steel-concrete composite beam, temporarily fix the first type of steel connecting piece at the end of the beam to the second type of steel connecting piece on the prefabricated steel pipe concrete column, and adjust the position and elevation of the beam; hoist the prestressed concrete composite floor, place it on the prefabricated layer of the prestressed steel-concrete composite beam, and ensure that the longitudinal stress bars and prestressed bars in the multiple types of steel bars extend to the composite layer, and the transversely distributed bars extend into the post-poured belt between adjacent plates or the reserved post-poured belt between beam plates; S3. Post-poured forming of the joint: formally connect the first type of steel connecting piece to the second type of steel connecting piece: first, use high-strength bolts to complete the shear connection of the first web plate to the second web plate, and then weld the butt joints of the upper and lower first flange plates and the second flange plates to complete the bending connection; arrange the plate end reinforcement and post-poured belt reinforcement, and weld, bind or anchor the multiple types of steel bars except the prestressed bars according to the construction standard; pour the composite layer concrete of the prestressed steel-concrete composite beam, and maintain it to the specified strength; the composite layer concrete is poured at one time, and the post-poured space including the beam-column joint area, the plate end and beam connection area, the plate side and beam connection area, and the post-poured belt between adjacent plates is filled at the same time; untension the prestressed steel bar bundle in the prestressed steel-concrete composite beam; perform corrosion and fireproofing treatment on the beam-column joint area.

[0016] Further, the prestressed steel-concrete composite beam in S1 is prefabricated according to the following steps: A1. Determine the embedded depth of the first type of steel connecting piece, the stop position of the flange, the extension length of the web plate, and the gradient slope according to the construction requirements; A2. Weld the first flange plate and the first web plate according to the construction requirement, and cut the extension section of the first web plate to form a transition zone with gradually decreasing cross-section height; A3. Embed the first flange plate and the first web plate into place; A4. Weld the upper steel backing plate at each upper beam longitudinal reinforcement of the beam framework, and weld the lower steel backing plate at each lower beam longitudinal reinforcement of the beam framework; A5. Perpendicularly weld the lower steel backing plate with the completed lower beam longitudinal reinforcement to the first flange plate of the lower part of the first steel connecting piece to form a continuous fillet weld, and perpendicularly weld the upper steel backing plate with the completed upper beam longitudinal reinforcement to the first flange plate of the upper part to form a continuous fillet weld; A6. Arrange the prestressed steel wire bundle at the bottom of the beam body, and perform tensioning and temporary anchoring according to the pretensioning process; A7. Set up the end formwork and the side formwork to form a pouring cavity for the prefabricated layer concrete; A8. Arrange the stirrups and other structural reinforcements to build the beam framework; A9. Pour the prefabricated layer concrete, and maintain it to the specified strength; A10. After the prefabricated layer concrete reaches the specified strength, release the tension of the pretensioning prestressed steel wire bundle to transmit the prestress to the prefabricated layer concrete through the bonding force.

[0017] Further, in step A3, the beam end steel plate is installed at the embedding position of the first flange plate and the first web plate, and the first flange plate and the first web plate are embedded into place based on the beam end steel plate; in step A4, the waist steel backing plate is welded at each waist reinforcement of the beam framework; and in step A5, the waist steel backing plate with the completed waist reinforcement is perpendicularly welded to the first web plate or / and the beam end steel plate to form a continuous fillet weld.

[0018] Further, in step A8, the stirrup spacing of the embedded part of the first steel connecting piece is smaller than the stirrup spacing of other parts; and a through groove is reserved on the plate surface of the embedded part of the first web plate at the end of the beam body, which is used for arranging the tie bar between the waist reinforcements of the beam framework.

[0019] Compared with the prior art, the present application has the following remarkable effects: (1) In the structural design, the pretensioning method of the prestressed concrete composite floor is once casted and formed, and the design of the thickness reduction section ensures the strength and performance of the floor itself and creates good conditions for the connection with the prestressed steel-concrete composite beam. The multiple types of steel bars extend out of the slab edge, which can better participate in the node stress and enhance the integrity and bearing capacity of the node. The prestressed steel-concrete composite beam is composed of a prefabricated layer and a composite layer. The prefabricated layer is once casted and formed by the pretensioning method to ensure the initial performance of the beam body, and the setting of the composite layer can better work with the floor to jointly bear the load. The segmental steel pipe of the concrete-filled steel tube column and the column body concrete poured inside, as well as the second type of steel connecting piece extending out of the pipe wall, provide a reliable basis for the connection with the beam.

[0020] (2) In the node connection, the design of each node is ingenious and reasonable. The connection between the slab end and the beam is through the multiple types of steel bars extending to the composite layer and forming a dense steel mesh with the beam skeleton, and the post-cast concrete fills and wraps, greatly enhancing the shear and bending capacity of the node. The connection between the slab side and the beam is through the transverse distribution bars extending into the reserved post-cast band and being wrapped by post-cast concrete, improving the cooperative stress performance of the node. The connection between adjacent slabs is through the transverse distribution bars connecting in layers and being wrapped by post-cast concrete, so that the floor can form a continuous whole floor and effectively transfer the load. The beam-column joint is connected by the bolted and welded mixed connection of the first and second type of steel connecting pieces, which realizes the smooth transition of the beam end stiffness, avoids brittle failure under strong earthquakes, improves the ductility deformation and energy dissipation performance of the node, and meets the seismic requirements.

[0021] (3) In the construction process, the combination of factory prefabrication and site installation improves the construction efficiency and quality controllability. Factory prefabrication can ensure the quality and precision of the components and reduce the workload and difficulty of site construction. Site installation is carried out in a reasonable order, including hoisting, temporary fixing, adjusting position and elevation, and subsequent formal connection, steel bar arrangement, concrete pouring and other steps, which ensures the smooth construction of the whole floor system. At the same time, the pretensioning of the prestressed steel wire bundle and the corrosion and fireproof treatment of the beam-column joint area further ensure the performance and durability of the floor system. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0023] Figure 1 The structural schematic diagram of the floor system in Example One (1); Figure 2Structure diagram of floor system in embodiment one (two); Figure 3 Structure diagram of beam-slab joint and slab-adjacent member joint in embodiment one (one); Figure 4 Structure diagram of beam-slab joint and slab-adjacent member joint in embodiment one (two); Figure 5 Structure diagram of beam-slab joint in embodiment one (one); Figure 6 Structure diagram of beam-slab joint in embodiment one (two); Figure 7 Structure diagram of slab body in embodiment one (one); Figure 8 Structure diagram of slab body in embodiment one (two); Figure 9 Structure diagram of slab body in embodiment one (one); Figure 10 Structure diagram of slab body in embodiment one (two); Figure 11 Structure diagram of beam-column joint in embodiment one (one); Figure 12 Structure diagram of beam-column joint in embodiment one (two); Figure 13 Assembly relationship diagram of first and second steel connecting pieces in embodiment one; Figure 14 Structure diagram of beam skeleton in embodiment one; Figure 15 End structure diagram of beam body in embodiment one (one); Figure 16 End structure diagram of beam body in embodiment one (two); Figure 17 End structure diagram of beam body in embodiment one (three); Marked number in figure: 1-prefabricated prestressed concrete composite floor, 2-prefabricated prestressed steel-concrete composite beam, 3-steel pipe concrete column; 101-slab body, 102-thickness reduction section, 103-slab top longitudinal reinforcement, 104-slab bottom longitudinal reinforcement, 105-upper layer transverse distribution reinforcement, 106-lower layer transverse distribution reinforcement, 107-key groove, 108-slab end reinforcement, 109-post-poured belt reinforcement; 201 - first type steel connector, 202 - beam body, 203 - beam framework, 2011 - first flange plate, 2012 - first web plate, 2013 - extension section, 2014 - upper steel pad plate, 2015 - lower steel pad plate, 2016 - waist steel pad plate, 2017 - beam end steel plate, 2018 - through slot, 2021 - prefabricated layer, 2022 - superimposed layer, 2031 - beam longitudinal reinforcement, 2032 - prestressed steel wire bundle, 2033 - waist reinforcement, 2034 - stirrup, 2035 - tie reinforcement, 2036 - prefabricated layer concrete; 301 - second type steel connector, 302 - segmented steel pipe, 3011 - transverse stiffening plate, 3012 - second web plate, 3013 - second flange plate, 3014 - connecting plate, 3015 - high-strength bolt; DETAILED DESCRIPTION

[0024] Embodiments of the present application are described in detail below with reference to the attached drawings, which show examples of embodiments of the present application. The same or similar components have the same or similar reference numbers throughout the drawings. The embodiments described below are examples and are intended to explain the present application, and should not be understood as limiting the present application.

[0025] In the description of the present application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, in the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0026] Figures 1 to 4This invention illustrates a first embodiment: a precast prestressed concrete beam-slab composite floor system, comprising a prestressed concrete composite floor slab 1, a prestressed steel-concrete composite beam 2, and a steel-concrete composite column 3. The prestressed concrete composite floor slab 1 includes a slab body 101 and internally reinforced with various types of steel bars. The slab body 101 is prestressed and cast in one piece using a pre-tensioning method, and has a gap at the upper end of the slab relative to the prestressed steel-concrete composite beam 2 to form a thinned section 102. The various types of steel bars extend outward from the edge of the slab. The prestressed steel-concrete composite beam 2 includes a beam body 202 and an internal beam frame 203. The beam body 202 is composed of a precast layer 2021 prefabricated in a factory and a cast-in-place layer. The precast layer 2022 is composed of a composite layer 2022, with first steel connectors 201 embedded at both ends; the precast layer 2021 is prestressed and cast in one piece using the pre-tensioning method; the height of the composite layer 2022 is consistent with the thickness of the non-thinned section of the slab 101; the steel-concrete composite column 3 includes segmented steel pipes 302 and internally cast column concrete; the segmented steel pipes 302 are also provided with second steel connectors 301 extending from their pipe walls; wherein: at the connection node between the end of the prestressed concrete composite floor slab 1 and the prestressed steel-concrete composite beam 2, the slab 101 rests on the precast layer 2021, and the longitudinal reinforcing bars and prestressing bars of the various types of reinforcing bars extend to the composite layer 2022. Together with the beam skeleton 203 of the composite layer 2022, they form a dense steel mesh; the post-cast concrete of the composite layer 2022 fills the joint area and wraps all the extending steel bars; at the connection node between the side of the prestressed concrete composite floor slab 1 and the prestressed steel-concrete composite beam 2, the transverse distribution bars of the multi-type steel bars extend into the reserved post-cast strip between the two, and are wrapped by the post-cast concrete of the composite layer 2022 along with the pouring of the composite layer 2022; at the connection node between two adjacent prestressed concrete composite floor slabs 1, the transverse distribution bars of the multi-type steel bars of the two are connected in layers and staggered within the post-cast strip reserved in the lateral joint, and are wrapped by the post-cast concrete of the composite layer 2022 along with the pouring of the composite layer 2022. The post-cast concrete encloses all the connecting steel bars; at the connection node between the prestressed steel-concrete composite beam 2 and the steel-concrete composite column 3, the first web plate 2012 of the first steel connector 201 and the second web plate 3012 of the second steel connector 301 are aligned with each other and shear-resistant connection is made using high-strength bolts 3015; the upper and lower first flange plates 2011 of the first steel connector 201 are aligned with the upper and lower second flange plates 3013 of the second steel connector 301 and then welded to form a bending-resistant connection; and the exposed parts of the first steel connector 201 and the second steel connector 301 are enclosed by the post-cast concrete of the composite layer 2022 along with the pouring of the composite layer 2022.

[0027] Please refer to 5 to Figure 10Specifically, the plate body 101 has a plate thickness of twice the plate thickness of the thickness-reduced section 102, which is a reasonable thickness design that ensures the load-bearing capacity of the floor slab in the main area and facilitates the filling of the post-cast concrete and the anchoring of the steel bars at the thickness-reduced section 102. The length of the thickness-reduced section 102 is 200-300 mm, which is a size range verified by construction and can meet the requirements of the concrete flowing into and wrapping the plate edge extension steel bars of the composite beam 2, and will not affect the overall structural performance of the floor slab due to the excessive length. At the same time, the plate body 101 is provided with a key groove 107 at the plate end connecting adjacent components, which further enhances the connection strength and integrity between the plate body 101 and the adjacent components, making the entire building structure more stable and reliable.

[0028] In specific implementation, the bonding surface of the thickness-reduced section 102 and the post-cast concrete of the composite layer 2022 is provided as a rough surface, and the plate end reinforcing bar 108 acting on the concrete of the composite layer 2022 is further arranged at the thickness-reduced section 102; the post-cast strip reinforcing bar 109 acting on the concrete of the composite layer 2022 is further arranged in the post-cast strip reserved at the lateral joint of the adjacent prestressed concrete composite floor slab 1 and / or the post-cast strip reserved between the plate side of the prestressed concrete composite floor slab 1 and the prestressed steel-concrete composite beam 2.

[0029] The arrangement of these reinforcing bars can significantly enhance the connection strength and cooperative working capacity between the concrete of the composite layer 2022 and the prestressed concrete composite floor slab 1 and the prestressed steel-concrete composite beam 2. The plate end reinforcing bar 108 can effectively disperse and transfer stress, prevent cracks and damage at the plate end during the stress process, and improve the overall stability of the floor slab. The post-cast strip reinforcing bar 109 can enhance the structural performance of the post-cast strip area, allowing adjacent components to better cooperate under stress and reducing cracks caused by factors such as temperature changes and concrete shrinkage. In order to further improve the bonding performance of the concrete of the composite layer 2022 and the thickness-reduced section 102, an interface agent can be applied to the rough surface. The interface agent can improve the bonding force between the concrete and the contact surface and enhance the overall integrity of the structure.

[0030] Specifically, the longitudinal stress bars are composed of the plate top longitudinal bar 103 and the plate bottom longitudinal bar 104, between which the upper layer transverse distribution bar 105 and the lower layer transverse distribution bar 106 are arranged; the plate top longitudinal bar 103 is a negative bending moment bar, and the plate bottom longitudinal bar 104 is a prestressed bar.

[0031] The negative bending moment of the longitudinal reinforcement 103 on the top of the slab can effectively resist the negative bending moment at the support, prevent cracks on the top of the slab, and ensure the structural safety of the slab at the support. The prestressed reinforcement 104 on the bottom of the slab can pre-stress the slab, improve the crack resistance and load-carrying capacity of the slab, and reduce the deformation of the slab during use. The upper transverse distribution reinforcement 105 and the lower transverse distribution reinforcement 106 can connect the longitudinal reinforcement into a whole, enhance the stability of the reinforcement cage, and also play a role in dispersing load, so that the slab bears force more evenly.

[0032] As shown in Figures 11 to 17 In the embodiment, the first steel connecting piece 201 includes a pair of non-continuous embedded beam bodies 202 at the ends, first flange plates 2011 receiving the longitudinal reinforcement 2031 of the upper and lower beams of the beam skeleton 203, and a first web plate 2012 arranged between the two; the end of the first web plate 2012 embedded in the beam body 202 extends towards the beam span direction, and forms an extension section 2013 with gradually decreasing cross-sectional height; the extension section 2013 is used to build a transition area with continuously smooth change of bending stiffness in the beam body 202; the second steel connecting piece 301 includes a pair of transverse stiffening plates 3011 with grouting holes arranged in the segmented steel pipe 302, and a second web plate 3012 arranged between the two; the second web plate 3012 extends out of the segmented steel pipe 302 and is aligned and connected with the first web plate 2012; the second flange plates 3013 receiving the segmented steel pipe 302 are also arranged at the upper and lower plate edges of the extension of the second web plate 3012 out of the segmented steel pipe 302; the upper and lower second flange plates 3013 are aligned and connected with the upper and lower first flange plates 2011, respectively.

[0033] In the embodiment, at least part of the cross-sectional height of the extension section 2013 changes linearly or nonlinearly. In the embodiment, preferably, the overall cross-sectional height of the transition section changes linearly, and the upper and lower plate edges thereof extend obliquely and relatively close to each other to form a wedge-shaped structure. The wedge-shaped structure further enhances the smoothness of the transition area, makes the change of bending stiffness more uniform, and thus further optimizes the seismic performance of the structure. In other embodiments, the overall cross-sectional height of the transition section can also change nonlinearly, or in a combination of linear and nonlinear changes, to meet specific engineering requirements or optimize the structural performance. In addition, the design of the cross-sectional height with nonlinear change or a combination of nonlinear and linear changes may involve more complex geometry and manufacturing process. However, in some cases, compared with linear change, this design can provide superior performance. For example, under certain dynamic response or load conditions, it can more effectively disperse stress and energy.

[0034] In specific applications, the combined floor system is constructed according to the following steps: S1. Factory prefabrication: prefabricate the prestressed concrete composite floor 1 to form the thickness-thinned section 102 and make the multi-type steel bars extend by a predetermined length; prefabricate the prefabricated layer 2021 of the prestressed steel-concrete composite beam 2 to install the first-type steel connecting piece 201 and build the beam skeleton 203; prefabricate the segment steel pipe 302 of the steel pipe concrete column 3 to install the second-type steel connecting piece 301; S2. On-site installation: hoist the segment steel pipe 302, pour the column body concrete and ensure the compactness through the grouting holes on the transverse stiffening plate 3011; hoist the prestressed steel-concrete composite beam 2, temporarily fix the first-type steel connecting piece 201 at the end of the beam to the second-type steel connecting piece 301 on the prefabricated steel pipe concrete column 3, and adjust the position and elevation of the beam; hoist the prestressed concrete composite floor 1, place it on the prefabricated layer 2021 of the prestressed steel-concrete composite beam 2, and ensure that the longitudinal stress bars and the prestressed bars in the multi-type steel bars extend to the composite layer 2022, and the transversely distributed bars extend into the post-cast strip between adjacent slabs or the reserved post-cast strip between the beam and the slab; S3. Post-cast forming of the joint: formally connect the first-type steel connecting piece 201 to the second-type steel connecting piece 301: first, use high-strength bolts 3015 to complete the shear connection of the first web plate 2012 and the second web plate 3012, and then weld the butt joints of the upper and lower first flange plates 2011 and the second flange plates 3013 to complete the bending connection; arrange the slab end reinforcing bars 108 and the post-cast strip reinforcing bars 109, and weld, tie or anchor the multi-type steel bars except the prestressed bars according to the construction standard; pour the composite layer 2022 concrete of the prestressed steel-concrete composite beam 2 and maintain it to the specified strength; the composite layer 2022 concrete is poured at one time, filling the post-cast space including the beam-column joint area, the slab end and beam connection area, the slab side and beam connection area, and the post-cast strip between adjacent slabs; tension the prestressed steel bar bundle 2032 in the prestressed steel-concrete composite beam 2; carry out corrosion and fireproofing treatment on the beam-column joint area. Specifically, the high-strength bolts 3015 are installed between the first web plate 2012 and the second web plate 3012 through the connecting plate 3014.

[0035] In the construction process, the prestressed steel-concrete composite beam 2 in S1 is prefabricated according to the following steps: A1. Determine the embedding depth of the first-type steel connecting piece 201, the flange stop position, the web plate extension length and the gradual change slope according to the construction requirements; A2. Weld the first flange plate 2011 and the first web plate 2012 according to the construction requirements, and cut and process the extension section 2013 of the first web plate 2012 to form a transition zone with gradually decreasing cross-sectional height; A3. Embed the first flange plate 2011 and the first web plate 2012 in place; A4. Welding the upper steel pad plate 2014 at each upper beam longitudinal reinforcement 2031 of the beam skeleton 203, and welding the lower steel pad plate 2015 at each lower beam longitudinal reinforcement 2031 of the beam skeleton 203; A5. Perpendicularly welding the lower steel pad plate 2015, which has completed the welding of the lower beam longitudinal reinforcement 2031, to the lower first flange plate 2011 of the first steel connecting piece 201 to form a continuous fillet weld; and perpendicularly welding the upper steel pad plate 2014, which has completed the welding of the upper beam longitudinal reinforcement 2031, to the upper first flange plate 2011 to form a continuous fillet weld; A6. Arranging the prestressed steel wire bundle 2032 at the bottom of the beam body 202, and performing tensioning and temporary anchoring according to the pretensioning process; A7. Setting up the end formwork and the side formwork to enclose the pouring cavity of the prefabricated layer concrete 2036; A8. Arranging the stirrup 2034 and other construction steel bars to build the beam skeleton 203; A9. Pouring the prefabricated layer concrete 2036, and curing to the specified strength; A10. After the prefabricated layer concrete 2036 reaches the specified strength, releasing the tension of the pretensioning prestressed steel wire bundle 2032 to transmit the prestress to the prefabricated layer concrete 2036 through the bonding force.

[0036] In a specific application, in step A1, the first flange plate 2011 of the first steel connecting piece 201 stops embedding at a distance from the end face of the beam body 202; and the first web plate 2012 continues to extend the extension segment 2013 with a length to form a transition area with the upper and lower edge transition slopes both being , and the geometric parameters satisfying the relationship （Ⅰ） :

[0037] In the formula: : the net span of the beam body 202; : the distance from the end of the first flange plate 2011 stopping embedding to the end of the beam body 202; : the length of the extension segment 2013; : the total length from the end of the beam body 202 to the end of the extension segment 2013; : the initial height of the extension segment 2013; : the total height of the cross section of the beam body 202; : the distance from the flange stopping position the web height of the beam body 202; : the remaining sectional height of the extension segment 2013 at the end point; : the web extension coordinate, whose positive direction points to the beam span direction, and the origin is located at the position where the first flange plate 2011 stops embedding; : the gradual change slope of the extension segment 2013; : the ratio of the extension length of the extension segment 2013 to the position where the first flange embedding stops; : the ratio of the minimum embedding depth of the first flange plate 2011 to the span; : the ratio of the residual height of the extension segment 2013 to the initial web height; : the ratio of the residual height of the extension segment 2013 to the height of the beam body 202; : the span utilization coefficient, ; : the gradual change slope adjustment factor of the load response; : the monotonically increasing function about the uniformly distributed load ; : the maximum bending moment design value of the beam body 202 at the span; : the yield strength of the steel material; : the design value of the uniformly distributed load on the beam.

[0038] The application of the above geometric parameter relationship formulas has important significance in actual engineering. When determining these parameters, factors such as the net span of the beam body 202 and the design value of the uniformly distributed load borne need to be considered comprehensively. By calculating and applying these relationship formulas, reasonable geometric parameters can be accurately determined for the first type steel connector 201, thereby ensuring that it plays the best mechanical performance in the beam body 202. For example, when the net span of the beam body 202 is large or the design value of the uniformly distributed load borne is high, the embedding depth of the first flange plate 2011 and the length of the extension segment 2013 need to be appropriately increased according to the relationship formulas to ensure sufficient bending resistance and stability. At the same time, the adjustment of the gradual change slope also needs to be accurately calculated according to the actual situation to ensure that the change of the bending stiffness in the transition area meets the design requirements.

[0039] The relationship formulas （Ⅰ） are verified by taking a standard floor frame beam of a high-rise office building as an example: 1. Design input parameters: 202 clear span of beam (Structural axis spacing minus support width); Beam 202 section height (Dimensions indicated on the structural construction drawings); Uniformly distributed load design value (Including the combined values ​​of dead load and live load); Maximum bending moment at mid-span (Calculation results from structural analysis software); steel yield strength (Measured values ​​using Q390 grade steel); Extension section 2013103 starting height (Specifications of HN550×200 steel section).

[0040] 2. Explanation of coefficient values:

[0041] 3. Parameter calculation process: (1) Determine the stopping position of the first flange plate 2011. : ; Values: ; Note: Meets seismic anchorage requirements ( ); satisfying moment transfer .

[0042] (2) Determine the web extension length : ; Note: Coefficient To achieve an efficient transition in the short extension phase of 2013.

[0043] (3) Determine the total length from the end of beam 202 to the end of extension 2013. : ; Validation constraints: .

[0044] (4) Determine the stiffness adjustment coefficient : ; Note: Logarithmic function response to load intensity, Corresponds to a moderately gradual slope.

[0045] (5) Determine the unilateral cutting slope : ; Explanation: Slope positively correlated with load , inversely correlated with span.

[0046] (6) Determine the web height function : ; Key points: ; ; (7) Determine the residual section height : ; Check constraints: ; (8) H-type steel total length : ; Beam body 202 end overhanging length 200mm for vertical load-bearing column 4 connection: .

[0047] 4. Extension section 2013 cutting rules: Upper plate edge cutting line: ; Lower plate edge cutting line: .

[0048] 5. Beam body 202 construction implementation and zoning: |← Left segment steel coverage area →|← Middle concrete area →|← Right segment steel coverage area →| 0 ──────3055mm ─────── 4945mm ─────── 8000mm; Beam body 202 inner first flange plate 2011101 and first web 2012102 complete area: 0 ~ 2350mm (flange + web); Extension section 2013 gradual change area: 2350 ~ 3055 mm (extension section 2013 section height 550 → 469 mm); Middle concrete area: 3055 ~ 4945 mm (pure concrete section); Symmetry: Two segment coverage areas are equal in length (each 3055 mm), with the midpoint aligned.

[0049] 6. Implementation effect: (1) Stress concentration factor reduced from traditional design of 2.8 to 1.5; (2) Steel usage saved by 28% (compared to full-length arrangement); (3) Node construction time reduced by 35%; (4) The plastic hinge rotation capacity is improved to 0.032 rad (satisfying the seismic requirements in high intensity areas).

[0050] In subsequent engineering design, the design scheme of the beam body 202 can be further optimized according to construction experience and results. For example, the coefficients in the geometric parameter relationship can be adjusted according to different engineering requirements and load conditions to achieve better mechanical properties and economic benefits. New materials can also be tried to improve the quality and performance of the beam body 202.

[0051] In this embodiment, in step A3, the beam end steel plate 2017 is installed at the cutoff position of the embedding of the first flange plate 2011 and the first web plate 2012, and the first flange plate 2011 and the first web plate 2012 are embedded in place based on the beam end steel plate 2017; in step A4, a waist steel pad plate 2016 is welded at each waist rib 2033 of the beam skeleton 203; in step A5, the waist steel pad plate 2016 that has completed the welding of the waist rib 2033 is vertically welded to the first web plate 2012 or / and the beam end steel plate 2017 to form a continuous fillet weld.

[0052] The strict implementation of these construction steps further guarantees the stability and structural strength of the beam body 202. The installation of the beam end steel plate 2017 provides an accurate reference for the embedding of the first flange plate 2011 and the first web plate 2012, ensuring the accuracy of their embedding positions and avoiding problems such as uneven stress concentration caused by position deviation. The welding of the waist steel pad plate 2016 at the beam joint waist rib 2033 and the formation of a continuous fillet weld by vertically welding it to the first web plate 2012 or the beam end steel plate 2017 can effectively enhance the connection strength of the beam body 202 joint, allowing the beam body 202 to work better in load bearing. From the perspective of the overall project, the implementation of these construction steps also improves the efficiency and quality of construction. Through precise installation and welding, errors and rework during construction are reduced, allowing the project to proceed smoothly according to the predetermined schedule. Moreover, standardized construction operations also provide reliable guarantees for subsequent engineering acceptance and quality evaluation, reducing the risk of potential safety hazards in the project.

[0053] In specific application, in step A8, the spacing of the stirrups 2034 bound around the embedded part of the first steel connecting member 201 is smaller than that of the other parts; a through slot 2018 is also reserved on the end part of the beam body 202 embedded in the first web plate 2012, which is used for arranging the tie bars 2035 through the waist bars 2033 of the beam framework 203. Such arrangement of the stirrups 2034 can effectively enhance the constraint of the embedded part of the first steel connecting member 201, and improve the shear capacity and overall stability of the region. The arrangement of the through slot 2018 and the tie bars 2035 can further enhance the connection and cooperative working capacity of the internal steel bars of the beam body 202, so that the beam body 202 can better transfer and disperse the force when bearing the load, and avoid the damage caused by local stress concentration.

[0054] In specific application, in step A8, the spacing of the stirrups 2034 bound around the embedded part of the first steel connecting member 201 is smaller than that of the other parts; a through slot 2018 is also reserved on the end part of the beam body 202 embedded in the first web plate 2012, which is used for arranging the tie bars 2035 through the waist bars 2033 of the beam framework 203. Such arrangement of the stirrups 2034 can effectively enhance the constraint of the embedded part of the first steel connecting member 201, and improve the shear capacity and overall stability of the region. The arrangement of the through slot 2018 and the tie bars 2035 can further enhance the connection and cooperative working capacity of the internal steel bars of the beam body 202, so that the beam body 202 can better transfer and disperse the force when bearing the load, and avoid the damage caused by local stress concentration.

[0055] In addition, the arrangement and tensioning of the high-strength prestressed steel wire bundle 2032 in step A6 is a key step to ensure that the beam body 202 has sufficient prestress. When arranging, the position of each steel wire bundle is accurately measured and marked. During tensioning, professional tensioning equipment is used and operated by experienced operators, and the tensioning force is strictly controlled according to the standard process of the pretensioning method to avoid problems such as cracks or deformation of the beam body 202 caused by uneven tensioning force. When arranging the stirrups 2034 and other construction steel bars in step A8, in addition to ensuring that the spacing, quantity and binding quality of the steel bars meet the design requirements, attention should also be paid to the anchoring length and overlapping method of the steel bars. Suitable anchoring length and correct overlapping method can ensure that the steel bars fully exert their strength when subjected to stress, further improving the stability of the beam skeleton 203. When pouring the precast layer of concrete 2036 in step A9, layered pouring and vibration compaction are important measures to ensure the quality of the concrete. The pouring thickness of each layer of concrete should be moderate, and the vibration time should be sufficient to ensure that there are no gaps or bubbles in the concrete. At the same time, attention should be paid to the pouring sequence to avoid phenomena such as concrete segregation. During the concrete curing stage, scientific and reasonable curing measures should be taken according to the actual environmental temperature and humidity conditions. For example, in a high-temperature and dry environment, the pouring frequency should be increased or a moisture-retaining material should be used to cover the surface of the concrete to prevent the water on the surface of the concrete from evaporating too quickly and causing cracks; in a low-temperature environment, insulation measures should be taken to ensure that the concrete can reach the specified strength at a suitable temperature. When releasing the pretensioning high-strength prestressed steel wire bundle 2032 in step A10, slow and uniform operation is the key. Too fast release speed will result in excessive loss of prestress, affecting the mechanical properties of the beam body 202. During the release process, the deformation of the beam body 202 should be monitored in real time, and once an abnormality is found, the release should be stopped immediately and appropriate treatment measures should be taken.

[0056] Please refer to Figure 5 In a specific application scenario, the prefabricated steel pipe concrete column 3 in S1 is prefabricated according to the following steps: B1: Fabricate a segment steel pipe 302 in a prefabrication factory, determine the position and extension length of the second steel connecting piece 301 embedded in the column; B2: Weld two transverse stiffening plates 3011 at the precise positions on the inner wall of the segment steel pipe 302, and reserve grouting holes on the transverse stiffening plates 3011; B3: Ensure that the upper and lower second flange plates 3013 of the second steel connecting piece 301 are aligned with the upper and lower transverse stiffening plates 3011, respectively, and then insert the second web plate 3012 of the second steel connecting piece 301 between the two transverse stiffening plates 3011 through the slot opened on the wall of the segment steel pipe 302; B4: The second web plate 3012 is extended to the node steel sleeve, and full penetration groove welding is performed on the segment steel pipe 302 inner pipe wall and the two transverse stiffening plates 3011 301. The second flange plate 3013 is welded to the segment steel pipe 302 outer pipe wall by continuous fillet welding.

[0057] In summary, in the structural design, the pre-tensioning method of the prestressed concrete composite floor slab 1 is once casted and formed, and the design of the thickness-reduced section 102 ensures the strength and performance of the floor slab itself and creates good conditions for the connection with the prestressed steel-concrete composite beam 2. The multiple types of steel bars extend out of the slab edge, which can better participate in the node stress and enhance the integrity and bearing capacity of the node. The prestressed steel-concrete composite beam 2 is composed of a precast layer 2021 and a composite layer 2022. The precast layer 2021 is once casted and formed by the pre-tensioning method to ensure the initial performance of the beam body 202. The setting of the composite layer 2022 can better work with the floor slab to jointly bear the load. The segment steel pipe 302 of the concrete-filled steel tube column 3 and the column body concrete poured inside, as well as the second type of steel connecting piece 301 extending out of the pipe wall, provide a reliable basis for the connection with the beam. In terms of node connection, the design of each node is ingenious and reasonable. The connection between the slab end and the beam is achieved by extending multiple types of steel bars to the composite layer 2022 and forming a dense steel mesh with the beam skeleton 203, which is then filled and wrapped with post-cast concrete, greatly enhancing the shear and bending resistance of the node. The connection between the slab side and the beam is achieved by extending the transverse distribution bars into the reserved post-cast zone and wrapping them with post-cast concrete, which improves the cooperative stress performance of the node. The connection between adjacent slabs is achieved by layering and interlacing the transverse distribution bars and wrapping them with post-cast concrete, allowing the floor slab to form a continuous whole floor system that effectively transmits loads. The beam-column joint is connected by bolted and welded mixed connection of the first and second type of steel connecting pieces, achieving smooth transition of beam end stiffness, avoiding brittle failure under strong earthquakes, improving the ductility deformation and energy dissipation performance of the node, and meeting the seismic requirements. In terms of construction technology, the combination of factory prefabrication and on-site installation improves the construction efficiency and quality controllability. Factory prefabrication can ensure the quality and precision of the components, reducing the workload and difficulty of on-site construction. On-site installation is carried out in a reasonable order, including hoisting, temporary fixing, adjusting position and elevation, and subsequent formal connection, steel bar arrangement, concrete pouring, etc., ensuring the smooth construction of the whole floor system. At the same time, the tensioning of the prestressed steel wire bundle 2032 and the corrosion and fireproof treatment of the beam-column joint area further ensure the performance and durability of the floor system.

[0058] The above disclosure is only a preferred embodiment of the present application, and of course cannot limit the scope of the present application. Those skilled in the art can understand that the above-mentioned processes can be implemented in whole or in part, and equivalent changes made in accordance with the claims of the present application still fall within the scope of the present application.

Claims

1. A prefabricated prestressed concrete beam-slab composite floor system, comprising a prestressed concrete composite floor slab, a prestressed steel-concrete composite beam, and a steel-concrete composite column, characterized in that: The prestressed concrete composite floor slab includes a slab body and various types of reinforcing bars inside; the slab body is prestressed and cast in one piece using the pre-tensioning method, and there is a gap at the upper part of the slab end relative to the prestressed steel-concrete composite beam to form a thickness reduction section; all the various types of reinforcing bars extend outward beyond the edge of the slab. The prestressed steel-concrete composite beam includes a beam body and an internal supporting beam frame; the beam body is composed of a precast layer prefabricated in the factory and a composite layer cast on site, and first steel connectors are embedded at both ends; the precast layer is prestressed and cast in one go using the pre-tensioning method; the height of the composite layer is consistent with the thickness of the non-thinning section of the slab. A steel-concrete composite column comprises segmented steel pipes and internally poured concrete column body; the segmented steel pipes are also provided with a second type of steel connector extending out of their pipe walls; Specifically: at the connection node between the end of the prestressed concrete composite floor slab and the prestressed steel-concrete composite beam, the slab rests on the precast layer, and the longitudinal reinforcing bars and prestressing bars in the multi-type steel bars extend to the composite layer to form a dense steel mesh together with the beam skeleton of the composite layer; the post-cast concrete of the composite layer fills the node area and wraps all the extending reinforcing bars. At the connection node between the side of the prestressed concrete composite floor slab and the prestressed steel-concrete composite beam, the transverse distribution bars of various types of steel bars extend into the reserved post-cast strip between the two, and are wrapped by the post-cast concrete of the composite layer along with the pouring of the composite layer. At the connection node of two adjacent prestressed concrete composite floor slabs, the transverse distribution bars of the various types of steel bars are connected in layers and staggered within the post-pouring strip reserved in the lateral splice. With the pouring of the composite layer, the post-pouring concrete of the composite layer encloses all the connecting steel bars. At the connection node between the prestressed steel-concrete composite beam and the steel-concrete composite column, the first web of the first type of steel connector and the second web of the second type of steel connector are aligned with each other and connected by high-strength bolts for shear resistance. The upper and lower first flange plates of the first type of steel connector are aligned with the upper and lower second flange plates of the second type of steel connector and then welded to form a bending connection. The exposed parts of the first type of steel connector and the second type of steel connector are encased in the post-cast concrete of the composite layer during the pouring of the composite layer.

2. The prefabricated prestressed concrete beam-slab composite floor system according to claim 1, characterized in that: The interface between the thickness reduction section and the post-cast concrete of the composite layer is set as a rough surface, and the thickness reduction section is also provided with slab end reinforcing bars that act on the composite concrete; post-cast strip reinforcing bars that act on the composite concrete are also arranged in the post-cast strip reserved at the lateral joint of the adjacent prestressed concrete composite floor slab and / or in the reserved post-cast strip between the slab side of the prestressed concrete composite floor slab and the prestressed steel-concrete composite beam.

3. The prefabricated prestressed concrete beam-slab composite floor system according to claim 2, characterized in that: The longitudinal reinforcement consists of top longitudinal reinforcement and bottom longitudinal reinforcement, with upper and lower transverse distribution reinforcement arranged between them; the top longitudinal reinforcement is a negative moment reinforcement, and the bottom longitudinal reinforcement is a prestressed reinforcement.

4. The prefabricated prestressed concrete beam-slab composite floor system according to any one of claims 1-3, characterized in that: The first type of steel connector includes a pair of non-continuous first flange plates embedded in the end of the beam and supporting the longitudinal reinforcement of the upper and lower beams of the beam frame, and a first web plate disposed between the two. A section of the first web plate embedded in the end of the beam extends toward the mid-span of the beam and forms an extension section with a gradually decreasing cross-sectional height. This extension section is used to construct a transition region in the beam where the bending stiffness changes continuously and smoothly. The second type of steel connector includes a pair of transverse stiffening plates with grouting holes disposed in the segmental steel pipe, and a second web plate disposed between the two. The second web plate extends horizontally out of the segmental steel pipe and is aligned and connected with the first web plate. At the upper and lower edges of the section of the second web plate extending out of the segmental steel pipe, second flange plates supporting the segmental steel pipe are respectively provided. The upper and lower second flange plates are aligned and connected with the upper and lower first flange plates respectively.

5. The prefabricated prestressed concrete beam-slab composite floor system according to claim 4, characterized in that: At least a portion of the cross-sectional height of the extension section varies linearly or nonlinearly.

6. The prefabricated prestressed concrete beam-slab composite floor system according to claim 5, characterized in that: The overall cross-sectional height of the extension section varies linearly, with its upper and lower edges extending obliquely and converging relatively to form a wedge-shaped structure.

7. The prefabricated prestressed concrete beam-slab composite floor system according to claim 6, characterized in that, The combined floor slab system is constructed according to the following steps: S1. Factory prefabrication: Precast prestressed concrete composite floor slabs form a thinned section and allow various types of steel bars to extend at predetermined lengths; The precast layer of the precast prestressed steel-concrete composite beam is used to install the first steel connector and construct the beam frame; The precast steel-concrete composite column is fitted with a second type of steel connector for its segmental steel pipes. S2. On-site installation: Hoist the segmental steel pipes, pour the column body concrete, and ensure compaction through the grouting holes on the transverse stiffening plate; Hoist the prestressed steel-concrete composite beam, temporarily fix the first steel connector at its end to the second steel connector on the precast steel-concrete column, and adjust the position and elevation of the beam. Hoist the prestressed concrete composite floor slab and place it on the precast layer of the precast prestressed steel-concrete composite beam, ensuring that the longitudinal reinforcing bars and prestressing bars of the various types of steel bars extend to the composite layer, and the transverse distribution bars extend into the post-cast strip between adjacent slabs or the reserved post-cast strip between beams and slabs. S3. Post-cast molding of nodes: Formal connection of the first and second steel connectors: First, use high-strength bolts to complete the shear connection between the first and second web plates, and then weld the butt joint between the upper and lower first flange plates and the second flange plates to complete the bending connection. Arrange the end reinforcement bars and post-cast strip reinforcement bars of the slab, and weld, tie or anchor the various types of steel bars other than prestressed tendons in accordance with the construction standards. The composite layer concrete of the prestressed steel-concrete composite beam is poured and cured to the specified strength; the composite layer concrete is poured in one go, simultaneously filling the post-pouring space including the beam-column joint area, the slab end and beam connection area, the slab side and beam connection area, and the post-pouring strip between adjacent slabs. The prestressed steel reinforcement bundles in the prestressed steel-concrete composite beam are released; Corrosion and fire prevention treatments were applied to the beam-column joint area.

8. The prefabricated prestressed concrete beam-slab composite floor system according to claim 7, characterized in that: The precast prestressed steel-concrete composite beams in S1 are precast according to the following steps: A1. Determine the embedding depth, flange stopping position, web extension length, and gradient slope of the first type of steel connector according to construction requirements; A2. Weld the first flange plate and the first web plate according to the construction requirements, and cut and process the extension section of the first web plate to form a transition zone with a gradually decreasing cross-sectional height; A3. Insert the first flange plate and the first web plate into place; A4. Weld upper steel plates to each upper longitudinal reinforcement of the beam frame and lower steel plates to each lower longitudinal reinforcement of the beam frame. A5. The lower steel plate, which has been welded to the longitudinal reinforcement of the lower beam, is vertically welded to the first flange plate at the bottom of the first steel connector to form a continuous fillet weld; the upper steel plate, which has been welded to the longitudinal reinforcement of the upper beam, is vertically welded to the first flange plate at the top to form a continuous fillet weld. A6. Arrange prestressed steel reinforcement bundles at the bottom of the beam, and tension and temporarily anchor them according to the pre-tensioning process; A7. Erect end formwork and side formwork to enclose and form the pouring cavity for precast concrete; A8. Arrange stirrups and other structural reinforcement to build the beam frame; A9. Pour the precast concrete layer and cure it to the specified strength; A10. After the precast concrete reaches the specified strength, the prestressed steel reinforcement bundles are released so that the prestress can be transferred to the precast concrete through bond force.

9. The prefabricated prestressed concrete beam-slab composite floor system according to claim 8, characterized in that: In step A3, a beam end steel plate is installed at the cut-off position where the first flange plate and the first web plate are embedded, and the first flange plate and the first web plate are embedded in place using the beam end steel plate as a reference. In step A4, a web steel plate is welded to each web reinforcement of the beam frame; in step A5, the web steel plates of the completed web reinforcements are vertically welded to the first web plate and / or the beam end plate to form a continuous fillet weld.

10. The connection node between the prestressed steel-concrete composite beam and the steel-concrete composite column according to claim 9, characterized in that: In step A8, the spacing of the stirrups tied in the embedded part of the first steel connector is smaller than the spacing of the stirrups in other parts; a through groove is also reserved on a section of the plate at the end of the first web embedded in the beam body, which is used to arrange tie bars through the web reinforcement of the beam skeleton.

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