CN108571071A - Prefabricated PC beams of concrete column connected node and construction method - Google Patents

Abstract

The present invention relates to a kind of prefabricated PC beams of concrete column connected node and construction method, interior joint includes concrete column and an at least beams of concrete, is fixedly connected by H profile steel between the beams of concrete and concrete column.Further, a column side steel plate is arranged in at least one side of the concrete column, the end set beam-ends steel plate of the beams of concrete, it is fixedly connected by the H profile steel between column side steel plate and the beam-ends steel plate, the present invention is easy to that construction, junction stress performance is superior and has stronger rigidity, solves the technical problem difficult in the connection of assembly concrete frame structure central sill Column border node.

Description

Assembled prestressed concrete beam-column joints and construction methods

technical field

The invention relates to the technical field of dry connection nodes of assembled building structures, in particular to an assembled prestressed concrete beam-column connection node and a construction method.

Background technique

With the rapid development of my country's economy, people's living standards continue to improve, and the requirements for housing are increasing. At the same time, the cast-in-place construction method of residential buildings is not compatible with the concept of sustainable development in my country. At present, my country urgently needs to solve the problems of high energy consumption, high pollution, and high investment in residential construction. Therefore, the Ministry of Housing and Urban-Rural Development of the Development and Reform Commission of my country has promulgated the "Green Building Action Plan", which clearly mentions the promotion of prefabricated assembly suitable for industrial production. Concrete structure, steel structure and other building systems, accelerate the development of prefabrication and assembly technology for construction projects, and improve the integration level of construction industrialization technology.

Prefabricated concrete structures have the following advantages:

(1) Green construction. The construction of prefabricated concrete structures can better meet the requirements of green construction such as land saving, energy saving, material saving, water saving and environmental protection, and reduce the negative impact on the environment, including reducing noise, preventing dust, reducing environmental pollution, cleaning transportation, reducing site Interference and conservation of water, electricity, materials and other resources and energy, follow the principles of sustainable development.

(2) The construction period is short. Since a large number of prefabricated concrete components are produced and maintained in the factory, the work on the construction site is only to hoist, assemble and reinforce the joints of the prefabricated components in the prefabrication plant, which not only does not require the installation of scaffolding and supports, but also reduces the seasonal factors. Influenced by the construction period, after the main structure is formed, the work of decoration, hydropower construction and other work is much less than that of cast-in-place construction, and even the masonry and plastering processes are omitted, thus greatly shortening the overall construction period.

(3) The components are of good quality. Concrete in precast plants does not require pumping, there is less water in the concrete, and the concrete has a higher strength grade than cast-in-place concrete. After the components are poured in the precast plant, the components will be steam cured to ensure the quality of the concrete. However, the curing concrete on the construction site cannot provide excellent conditions for steam curing, and is also affected by the weather. The curing quality cannot be compared with that of the precast plant.

However, prefabricated concrete structures also have some disadvantages of their own, such as complex joint connections. The current main connection node form requires on-site binding of steel bars, pouring of concrete, and scaffolding, formwork, etc., which brings hidden dangers to the quality of the joints, requires high construction technology, and limits the use of precast concrete components to a certain extent.

Contents of the invention

The purpose of the present invention is to provide an assembled prestressed concrete beam-column joint and construction method. The present invention is easy to construct, has superior mechanical performance at the joint and has strong rigidity, and solves the problem of the beam-column joint in the assembled concrete frame structure. Technical issues with connection difficulties.

In order to solve the above problems, the present invention provides an assembled prestressed concrete beam-column connection node, which includes a concrete column and at least one concrete beam, and the concrete beam and the concrete column are fixedly connected by H-shaped steel.

Preferably, at least one side of the concrete column is provided with a column side steel plate, and the end of the concrete beam is provided with a beam end steel plate, and the column side steel plate and the beam end steel plate are fixedly connected by the H-shaped steel .

Preferably, several prestressed tendons in the concrete column respectively pass through the steel plates on the side of the column, and the steel plates on the side of the column are fixed to the side of the concrete column through anchors for the prestressed tendons in the column;

A plurality of beam internal prestressed tendons in the concrete beam pass through the beam end steel plates respectively, and the beam end steel plates are fixed to the ends of the concrete beam by beam internal prestressed tendon anchors.

Preferably, there is a gap for on-site welding between the prestressed tendon anchor in the column and the flange of the H-shaped steel.

Preferably, the prestressed tendons in the column are perpendicular to the plane of the steel plate on the side of the column, and the H-shaped steel is perpendicular to the plane of the steel plate on the side of the column;

The prestressed tendon in the beam is perpendicular to the plane of the steel plate at the beam end, and the H-shaped steel is perpendicular to the plane of the steel plate at the beam end.

Preferably, a number of studs inside the column are also provided in the concrete column, and several studs inside the column are welded to the steel plate on the side of the column;

The concrete beam is also provided with a number of studs in the beam, and the studs in the beam are welded to the steel plate at the end of the beam.

Preferably, the stud inside the column is perpendicular to the plane of the steel plate on the side of the column;

The beam inner peg is perpendicular to the plane of the beam end steel plate.

Preferably, the studs in the column and the steel plate on the side of the column are connected by stud welding or drawn arc stud welding;

The studs in the beam and the steel plates at the beam end are connected by stud welding or drawn arc stud welding.

Preferably, one end of the H-shaped steel is welded to the column-side steel plate, and the other end is welded to the beam-end steel plate.

Preferably, a beam-column connecting steel plate is also welded on the steel plate on the side of the column, holes are provided at the corresponding positions of the beam-column connecting steel plate and the H-shaped steel web, and the beam-column connecting steel plate and the H-shaped steel are connected by bolts. The web fixed connection.

Preferably, the beam-column connecting steel plate is perpendicular to the plane of the column-side steel plate.

Preferably, the joints between the H-shaped steel and the steel plate at the column side and the steel plate at the beam end are welded with penetration groove or fillet weld;

The joints between the beam-column connecting steel plate and the column-side steel plate are welded with penetration groove or fillet weld.

Preferably, a column side steel plate is provided on both sides of the concrete column, and the outer sides of the two column side steel plates are fixedly connected to the end of a concrete beam through an H-shaped steel respectively, and the two column side steel plates are respectively connected to The two sides of the prestressed tendon in the column.

The present invention also provides a construction method for an assembled prestressed concrete beam-column connection node, which includes the following steps:

Step 1, making the concrete column: open a hole through the steel plate on the side of the column so that the prestressed tendon in the column can pass through, place the steel plate on the side of the column on the formwork of the concrete column according to the position specified in the design, and then discharge the longitudinal reinforcement and hoop inside the column The ribs form a reinforcement cage, and then the studs in the column and the steel plates on the side of the column are welded and placed in the formwork of the concrete column. The prestressed tendons in the columns on both sides are stretched, and then the longitudinal reinforcements and stirrups in the columns are bound, and the concrete is poured. Finally, the beam-column connecting steel plate is welded on the steel plate on the side of the column;

Step 2, making concrete beams: Open the steel plate at the end of the beam so that the prestressed tendons in the beam can pass through, place the steel plate at the end of the beam on the formwork of the concrete beam according to the position specified in the design, and then discharge the longitudinal reinforcement and inner hoop of the beam The ribs form a reinforcement cage, and then the pegs in the beam and the steel plates at the beam end are welded and placed in the formwork of the concrete beam, and the prestressed tendons in the beam pass through the formwork of the concrete beam and the steel plate at the end of the beam and are stretched to bind the longitudinal direction of the beam. After the curing is completed, the H-shaped steel is welded to the steel plate at the end of the beam, and then the prestressed tendons in the beam are fixed by the prestressed tendon anchors in the beam;

Step 3, factory hoisting: Transport the prepared concrete columns and concrete beams to the construction site, fix the H-shaped steel web and the beam-column connecting steel plate with bolts, and then weld the H-shaped steel flange and the column side steel plate.

Step 1 and Step 2 are in no particular order.

Compared with the prior art, the present invention has the following technical effects:

(1) The present invention connects the assembled concrete beam-column by the H-shaped steel, which greatly reduces the difficulty of connecting the assembled concrete beam-column node;

(2) The present invention greatly reduces the difficulty of joint connection of assembled concrete beams and columns through the hybrid connection of H-shaped steel and steel plate bolt welding;

(3) The present invention simplifies the construction process, accelerates the construction speed, and the positioning of beams and columns is more accurate, which brings convenience for subsequent construction;

(4) the present invention uses prestressed tendon, has improved the rigidity of concrete column side embedded part and concrete beam end face embedded part, has reduced deformation;

(5) The present invention adopts studs, so that the shearing effect of the embedded part in the concrete column and the embedded part at the end of the concrete beam is further improved;

(6) At the concrete beam-column node in the present invention, the concrete column runs through up and down, maintaining the integrity of the concrete column.

(7) The present invention is mainly used in fabricated concrete frame structures and frame shear wall structures, and can also be used in combination with various supporting components.

Of course, any product implementing the present invention does not necessarily need to achieve all the above-mentioned advantages at the same time.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without any creative work. In the attached picture:

Fig. 1 is the exterior view of the assembled prestressed concrete beam-column connection node of the present invention;

Fig. 2 is the three-dimensional schematic diagram of the assembled prestressed concrete beam-column connection node of the present invention;

Fig. 3 is the schematic plan view of the assembled prestressed concrete beam-column connection node of the present invention;

Fig. 4 is the A-A sectional view of the assembled prestressed concrete beam-column connection node of the present invention;

Fig. 5 is the B-B sectional view of the assembled prestressed concrete beam-column connection node of the present invention;

Fig. 6 is a C-C cross-sectional view of a schematic diagram of a prestressed concrete beam-column connection node of the present invention.

Detailed ways

The prefabricated prestressed concrete beam-column connection node provided by the present invention will be described in detail below in conjunction with FIGS. The operation process, but the protection scope of the present invention is not limited to the following examples, those skilled in the art can modify and embellish it within the scope of not changing the spirit and content of the present invention.

Please refer to FIG. 1 to FIG. 6 , an assembled prestressed concrete beam-column connection node includes a concrete column 1 and at least one concrete beam 3 , and the concrete beam 3 and the concrete column 1 are fixedly connected by H-shaped steel 2 . In this embodiment, the end of the concrete beam 3 can be arranged at any position on any side of the concrete column 1 according to actual needs, and it can also be that the two sides of the concrete column 1 are respectively connected to a concrete beam 3 at the same time. This is not limited, that is, at least one side of the concrete column 1 is provided with a column side steel plate 15, and the end of the concrete beam 3 is provided with a beam end steel plate 31, between the column side steel plate 15 and the beam end steel plate 31 The connection is fixed through the H-shaped steel 2. In this embodiment, the structures of the connection nodes between the concrete column 1 and all the concrete beams 3 are the same, and the specific structure of the connection nodes between the end of the concrete beam 3 and the side of the concrete column 1 is as follows:

The concrete column 1 is provided with column internal longitudinal reinforcement 11, column internal stirrup 12, column internal prestressing reinforcement 13 and column internal studs, column internal stirrup 12 is located on the outside of column internal longitudinal reinforcement 11, and the inside of the concrete column 1 A number of prestressed tendons 13 in the column respectively pass through the steel plates 15 on the side of the column, and the steel plates 15 on the side of the column are fixed on the side of the concrete column 1 through anchors 14 for the prestressed tendons in the column, that is, the steel plates in the column are located at The outer side of the stirrup 12 in the column is flush with the outer surface of the concrete column 1. A number of holes are reserved on the steel plate 15 on the side of the column, and the prestressed tendons 13 in the column pass through several holes respectively, and the steel plate 15 on the side of the column is fixed on the side of the concrete column 1 through the anchors 14 of the prestressed tendons in the column to form a The embedded part in the column, the peg 16 in the column is welded with the steel plate 15 on the side of the column.

Further, there is a gap available for on-site welding between the prestressed tendon anchor 14 in the column and the flange of the H-shaped steel 2, and the prestressed tendon 13 in the column can be stretched before pouring the concrete column 1, or Or reserved holes are stretched on the hardened concrete column 1, and fixed with prestressed tendon anchors 14 in the column after tensioning.

Concrete beam 3 is provided with internal beam stirrups 33, beam internal prestressed tendons 32 and beam internal studs 35, beam internal stirrups 33 are located on the outside of beam internal prestressed tendons 32, and some beam internal prestressed ribs in concrete beam 3 The ribs 32 pass through the beam end steel plates 31 respectively, and the beam end steel plates 31 are fixed on the end face of the concrete beam 3 by the prestressed tendon anchors 34 in the beam, that is, the beam inner steel plates are located at the outer ends of the beam inner stirrups 33 , and flush with the outer end face of the concrete beam 3. A number of holes are reserved on the steel plate 31 at the beam end, and the prestressed tendons 32 in the beam pass through several holes respectively and the steel plate 31 at the end of the beam is fixed on the end of the concrete beam 3 through the anchorage 34 for the prestressed tendons in the beam. The embedded part in the beam is formed, and the pegs 35 in the beam are welded with the steel plate 31 at the beam end.

Further, the prestressed tendons 13 in the column are perpendicular to the plane of the steel plate 15 on the column side, the longitudinal ribs 11 in the column are parallel to the plane of the steel plate 15 on the side of the column, and the H-shaped steel 2 is parallel to the plane of the steel plate 15 on the side of the column. vertical;

The beam inner prestressed tendon 32 is perpendicular to the plane of the beam end steel plate 31 , and the H-shaped steel 2 is perpendicular to the plane of the beam end steel plate 31 .

Further, the column inner peg 16 is perpendicular to the plane of the column side steel plate 15;

The beam inner peg 35 is perpendicular to the plane of the beam end steel plate 31 .

Further, the column inner stud 16 is connected to the column side steel plate 15 by stud welding or drawn arc stud welding;

The beam inner studs 35 are connected to the beam end steel plates 31 by stud welding or drawn arc stud welding.

In this embodiment, one end of the H-shaped steel 2 is welded to the column-side steel plate 15, that is, the upper flange, web and lower flange of one end of the H-shaped steel 2 are respectively welded to the column-side steel plate 15, and the other end is welded to the column-side steel plate 15. The beam end steel plate 31 is welded, that is, the upper flange, the web and the lower flange of the other end of the H-shaped steel 2 are welded to the beam end steel plate 31 respectively.

A beam-column connecting steel plate 4 is also welded on the column side steel plate 15, holes are arranged on the corresponding positions of the beam-column connecting steel plate 4 and the web of the H-shaped steel 2, and the beam-column connecting steel plate 4 is connected to the steel plate 4 by bolts 5. The web of H-shaped steel 2 is fixedly connected.

Further, the beam-column connecting steel plate 4 is perpendicular to the plane of the column-side steel plate 15 .

Further, the joints between the H-shaped steel 2 and the steel plate 15 at the column side and the steel plate 31 at the beam end are all welded with penetration groove or fillet weld;

The joints between the beam-column connecting steel plate 4 and the column-side steel plate 15 are welded with penetration groove or fillet weld.

As an example, a column-side steel plate 15 is arranged on both sides of the concrete column 1, and the outer sides of the two column-side steel plates 15 are fixedly connected to the end of a concrete beam 3 through an H-shaped steel 2, respectively. The column side steel plates 15 are respectively connected to both sides of the prestressed tendons 13 in the column. In this embodiment, the column-side steel plates 15 on both sides of the concrete column 1 have a symmetrical structure.

In the present invention, there is no need to pour concrete at the junction of the H-shaped steel 2 .

The present invention also provides a construction method for an assembled prestressed concrete beam-column connection node, which includes the following steps:

Step 1, making the concrete column: open a hole through the steel plate on the side of the column so that the prestressed tendon in the column can pass through, place the steel plate on the side of the column on the formwork of the concrete column according to the position specified in the design, and then discharge the longitudinal reinforcement and hoop inside the column The ribs form a reinforcement cage, and then the studs in the column and the steel plates on the side of the column are welded and placed in the formwork of the concrete column. The prestressed tendons in the columns on both sides are stretched, and then the longitudinal reinforcements and stirrups in the columns are bound, and the concrete is poured. Finally, the beam-column connecting steel plate is welded on the steel plate on the side of the column;

Step 2, making concrete beams: Open the steel plate at the end of the beam so that the prestressed tendons in the beam can pass through, place the steel plate at the end of the beam on the formwork of the concrete beam according to the position specified in the design, and then discharge the longitudinal reinforcement and inner hoop of the beam The ribs form a reinforcement cage, and then the pegs in the beam and the steel plates at the beam end are welded and placed in the formwork of the concrete beam, and the prestressed tendons in the beam pass through the formwork of the concrete beam and the steel plate at the end of the beam and are stretched to bind the longitudinal direction of the beam. After the curing is completed, the H-shaped steel is welded to the steel plate at the end of the beam, and then the prestressed tendons in the beam are fixed by the prestressed tendon anchors in the beam;

Step 3, factory hoisting: Transport the prepared concrete columns and concrete beams to the construction site, fix the H-shaped steel web and the beam-column connecting steel plate with bolts, and then weld the H-shaped steel flange and the column side steel plate.

Step 1 and Step 2 are in no particular order.

The invention proposes an assembled prestressed concrete beam-column joint form, and the section and reinforcement of the assembled concrete member are determined according to the structural bearing capacity and deformation requirements in the design. The thickness of the pre-embedded steel plate, the diameter, length, and quantity of the studs, and the specifications of the prestressed tendons are designed according to the ultimate bearing capacity of the beam and column.

The following uses the prestressed concrete frame structure beam-column joint connection as an example to illustrate the use process. The frame beam cross-section size in the pre-fabricated prestressed concrete frame is 200mm×400mm, and the frame column cross-section size is 400mm×400mm. The reinforcement in the tension area of the frame beam is 3AT18 prestressed threaded steel bar, the reinforcement in the compression area is 2AT18 prestressed threaded steel bar, fixed with nut anchors, and the stirrup is C8@100/200(2). The longitudinal reinforcement of the frame column is 4C18, and the stirrup is C8@100/200(2). The prestressed tendons in the frame columns are 4AT18, with a horizontal spacing of 114mm and a vertical spacing of 360mm. The length of the steel plate at the end of the concrete beam is 400mm, the width is 200mm, and the thickness is 20mm. There are 6 studs in the concrete beam. The diameter of the studs is 13mm and the length is 120mm. There are 3 rows along the height direction of the beam section with a spacing of 80mm, and 2 rows along the width direction of the beam section with a spacing of 80mm. The length of the steel plate on the side of the concrete column is 450mm, the width is 200mm, and the thickness is 20mm. There are 8 studs in the concrete column. The diameter of the studs is 13mm and the length is 80mm. There are 4 rows along the longitudinal axis of the column with a spacing of 80mm, and 2 rows perpendicular to the longitudinal axis of the column with a spacing of 80mm. The length of the I-beam is 300mm, the height is 240mm, the width is 160mm, the thickness of the web is 12mm, and the thickness of the flange is 16mm. The beam-column connection steel plate is 160mm long, 80mm wide and 12mm thick. The bolts are M16.

What is disclosed above is only a specific embodiment of the present application, but the present application is not limited thereto, and any changes conceivable by those skilled in the art shall fall within the protection scope of the present application.

Claims (14)

1. a kind of prefabricated PC beams of concrete column connected node, which is characterized in that including concrete column and an at least coagulation Tu Liang is fixedly connected between the beams of concrete and concrete column by H profile steel.

2. prefabricated PC beams of concrete column connected node as described in claim 1, which is characterized in that the concrete column At least one side be arranged a column side steel plate, the end set beam-ends steel plate of the beams of concrete, column side steel plate with it is described It is fixedly connected by the H profile steel between beam-ends steel plate.

3. prefabricated PC beams of concrete column connected node as claimed in claim 2, which is characterized in that the concrete column Presstressed reinforcing steel is each passed through column side steel plate in interior several columns, and by presstressed reinforcing steel anchorage in column by column side steel plate It is fixed on the side of the concrete column；

Presstressed reinforcing steel is each passed through the beam-ends steel plate in several beams in the beams of concrete, and passes through presstressed reinforcing steel anchor in beam Tool is by the beam-ends Interal fixation in the end of the beams of concrete.

4. prefabricated PC beams of concrete column connected node as claimed in claim 3, which is characterized in that answered in advance in the column There are the gaps for site welding between power muscle anchorage and the edge of a wing of the H profile steel.

5. prefabricated PC beams of concrete column connected node as claimed in claim 3, which is characterized in that answered in advance in the column Power muscle is vertical with the plane of column side steel plate, and the H profile steel is vertical with the plane of column side steel plate；

Presstressed reinforcing steel is vertical with the plane of beam-ends steel plate in the beam, and the H profile steel and the plane of the beam-ends steel plate are hung down Directly.

6. prefabricated PC beams of concrete column connected node as claimed in claim 3, which is characterized in that the concrete column It is inside additionally provided with peg in several columns, peg is welded with column side steel plate in several columns；

Peg in several beams is additionally provided in the beams of concrete, peg is welded with the beam-ends steel plate in several beams.

7. prefabricated PC beams of concrete column connected node as claimed in claim 6, which is characterized in that peg in the column It is vertical with the plane of column side steel plate；

Peg is vertical with the plane of beam-ends steel plate in the beam.

8. prefabricated PC beams of concrete column connected node as claimed in claim 6, which is characterized in that peg in the column It is connect using nail solder or arc pulling type welding of peg with column side steel plate；

Peg is connect with beam-ends steel plate using nail solder or arc pulling type welding of peg in the beam.

9. prefabricated PC beams of concrete column connected node as claimed in claim 2, which is characterized in that the H profile steel One end is welded with column side steel plate, and the other end is welded with the beam-ends steel plate.

10. prefabricated PC beams of concrete column connected node as claimed in claim 9, which is characterized in that column side steel It also welds a beam-to-column joint steel plate on plate, hole is all provided on the corresponding position of the beam-to-column joint steel plate and H profile steel web, lead to Bolt is crossed to be fixedly connected with the beam-to-column joint steel plate with the web of H profile steel.

11. prefabricated PC beams of concrete column connected node as claimed in claim 10, which is characterized in that the beam column connects It is vertical with the plane of column side steel plate to connect steel plate.

12. prefabricated PC beams of concrete column connected node as claimed in claim 9, which is characterized in that the H profile steel point It is not all made of with the junction of column side steel plate and beam-ends steel plate and melts groove welding or fillet weld seam；

The junction of the beam-to-column joint steel plate and column side steel plate, which is all made of, melts groove welding or fillet weld seam.

13. prefabricated PC beams of concrete column connected node as claimed in claim 3, which is characterized in that the concrete A column side steel plate is respectively set in the two sides of column, and the outside of two column side steel plates passes through a H profile steel and a beams of concrete respectively End be fixedly connected, two column side steel plates are connected to the both sides of presstressed reinforcing steel in the column.

14. a kind of construction method of prefabricated PC beams of concrete column connected node, which is characterized in that including following step Suddenly：

Step 1 makes concrete column：Make the perforative hole of presstressed reinforcing steel in column by being opened on the steel plate of column side, according to the position of design code It sets and column side steel plate is shelved in the template of concrete column, then discharge and indulge stirrup in muscle and column in column and form steel reinforcement cage, then by column Interior peg is placed on the welding of column side steel plate in the template of concrete column, and by presstressed reinforcing steel in column pass through concrete column template and Column side steel plate simultaneously carries out tensioning, reserves presstressed reinforcing steel duct in the column on the other two sides of column, and carry out tensioning, then binds in column and indulges Stirrup in muscle and column, casting concrete wait after the completion of conserving, and leads in multicolumn presstressed reinforcing steel in presstressed reinforcing steel anchorage fixed column, most Beam column junction steel plate is welded on the steel plate of column side afterwards；

Step 2 makes beams of concrete：Make the perforative hole of presstressed reinforcing steel in beam by being opened on beam-ends steel plate, according to the position of design code It sets and beam-ends steel plate is shelved in the template of beams of concrete, then discharge and indulge stirrup in muscle and beam in beam and form steel reinforcement cage, then by beam The welding of interior peg and beam-ends steel plate is placed in the template of beams of concrete, and by presstressed reinforcing steel in beam pass through concrete beam mould board and Beam-ends steel plate simultaneously carries out tensioning, binds and indulges stirrup in muscle and beam in beam, then casting concrete, is waited after the completion of conserving, first by H-type Steel and beam-ends steel plate weld, then pass through presstressed reinforcing steel in presstressed reinforcing steel anchorage fixed beam in beam；

Step 3, factory's lifting：The concrete column made and beams of concrete are transported to construction site, H is bolted Shape steel web and beam-to-column joint steel plate, then the welded H section steel edge of a wing and column side steel plate.

Step 1 and step 2 sequence in no particular order.