GB2329197A

GB2329197A - Pre-cast structural building method

Info

Publication number: GB2329197A
Application number: GB9719526A
Authority: GB
Inventors: Peter Pun
Original assignee: PYPUN E P C PROJECTS Ltd
Current assignee: PYPUN E P C PROJECTS Ltd
Priority date: 1997-09-12
Filing date: 1997-09-12
Publication date: 1999-03-17
Also published as: GB9719526D0

Abstract

A method of forming structural joints between vertical column shells 1 comprises placing the shells in position in alignment. Floor beams 2 are supported by steel frames 7 temporarily attached to the outer surface of lower column shells adjacent their top surfaces. In-situ concrete (shown shaded) is flowed around the opposing ends of the column shells to secure these column shells together and to the floor beams 2, while also forming a column collar 5.

Description

PRE-CAST STRUCTURAL BUILDING METHOD The invention relates to a pre-cast structural building method.

In UK Patent Specification No. 1536134, a structural method for decking of floor system is disclosed that relates to securing planks and beams by in-situ reinforced concrete. During building, the beams and planks are assembled together and then concrete is poured to form "wet joints" so that the different types of floor or decking structural elements act compositely together. The present invention provides a new building method which is, particularly but not exclusively, for the aforesaid system.

According to the invention there is provided a method of making a structural joint for a building comprising positioning a first pre-cast column shell vertically, casting concrete in the column shell to a level below the top of the column shell, temporarily supporting or forming at least one lateral support beam with its end adjacent the top of the first column shell, placing a second precast column shell with its bottom end above and in line with the top end of the first column shell, and securing the at least one support beam to the column shells by means of in-situ reinforced concrete that is flowed around the said ends of the first and second column shells to form a collar and which fills up the top of the first column shell and at least a bottom part of the second column shell.

The method may include temporarily supporting an at least one pre-cast floor beam by a steel frame removably fixed to an outside of the first column shell adjacent the top thereof.

The concrete is preferably flowed to fill the second column shell to generally adjacent but below the top of the second column shell.

The method may include providing formwork to form a lateral tie beam with its one end adjacent the top of the first column shell, and forming the tie beam or part of it using the in-situ reinforced concrete that is flowed around the said ends of the column shells. In suitable situations, the tie beam may be formed by using a pre-cast shell beam.

Pre-cast floor planks may be secured by using the flowed in-situ reinforced concrete.

Free ends of reinforcement may be fixed in position and/or reinforcements placed within the in-situ joint cavities before flowing the concrete around the column shell ends.

Methods of making structural joints according to the invention will now be described by way of example with reference to the accompanying drawings in which : Figure 1 is a top plan view of one floor area; Figure 2 is a section 2-2 of Figure 1; Figure 3 is a section 3-3 of Figure 1; Figure 4 is a sectional side view of part of a building under construction; Figure 5 shows sectional views of two different type of column shells; Figure 6 shows sectional views of two different types of pre-cast floor beams; and Figure 7 shows in cross-section a different type of ends for column shell joints.

Referring to the drawings, in Figure 1 there are a number of pre-cast column shells 1. A number of pre-cast floor beams (not shown) extend between the column shells and support opposite ends of floor planks 3. Tie beams 4 are provided as shown and are formed in-situ with column collars. The figure shows the in-situ formed parts of the structure in grey shading. Normally the floor will have a concrete topping when the pre-cast floor is completed, which may be formed at the same time as the in-situ or grey areas parts, or later as explained below.

In Figures 2 and 3, the components of Figure 1 are identified by the same numbers and the floor beams 2 are now clearly shown. As before in-situ concrete regions are shown in grey shading. Figures 1 and 2 show floor toppings 6. Metal frame supports 7 temporarily clamp to and are supported by outsides of lower column shells adjacent their top ends. Reinforcement steel cages (not shown) are provided in the spaces between the in line column shells, and channel voids in the beams 2. The voids in the beams 2 are to be filled with a concrete filling 8.

The column shells are shown with cavities 9 that are filled during building with in-situ concrete, and reinforcement wires when appropriate. Apertures 10 may be formed in the column shells to permit reinforcement ends of the beams to pass through the shells. The lower ends of the column shells are formed with spigots 11 that fit over and around the top surfaces of the lower column ends.

In accordance with the invention, the method of making structural joints will be explained with reference to Figure 4 and is as follows : 1. A bottom column shell is cast into a foundation slab 12 well below ground level and its central cavity 9 is filled with concrete to a minimum of 150mm from the soffit of a first floor beam 2. The lower column shell 1 is designed to take construction dead loads so that little or no temporary work is required to support floor beams 2 and planks 3 before casting in situ collars 5.

2. Steel support structures 7 are clamped to the outside of and supported adjacent a top end of the lower column shell. Floor beams 2 are placed with their ends adjacent the top of the lower column shell.

Planks 3 are supported by the beams 2. The beams 2 may be propped if required.

3. An upper column shell is positioned with its bottom end above and in line with the first column shell; the spigotted lower end 11 fits over the top end of the lower column shell. A reinforcement steel cage 8 is fitted in the cavity within the joint of the upper and lower column shells and any ends of the floor beam reinforcement wires (not shown) tied off.

4. In-situ collars 5 are cast by flowing concrete around the bottom end of the upper column shell to fill the top of the lower column shell and so as to secure both columns together and to the floor beams 2. The cavity 9 of the upper column shell will normally be filled in this step to 150mm below the soffit of the next floor beams. (The planks will also be secured to the beams 2 in a manner fully explained in UK Patent Specification No. 1536134) In-situ floor topping 6 together with the beam concrete filling 8 may be placed at this stage, or alteratively cast in a later operation. Conveniently, the topping of two or more floors may be carried out together at a later time. One advantage of embodiments of this invention is that the topping and other "finishing" such as the beam concrete filling can be carried out later. Floors may therefore be built at a greater speed because it is not necessary to wait for finishing surfaces (e.g. topping surfaces) to fully cure before proceeding to the next floor above.

It will be appreciated that formwork will be required for the tie beams 4. However, in suitable situations, the tie beams may be formed using shell beams similar to the precast floor beams 2. In that case the shell beams held in position for in-situ securing by the support frames 7.

It will be noted that in the described method pre-cast floor beams 2 are used. The method may be carried out using only formed in-situ support beams, if preferred.

However, in each or all cases the wet joint and securing formed by the in-situ reinforced concrete serves to join the ends of the columns and the adjacent lateral beams in one operation.

Figure 5 shows the shape of two types of otherwise known column shells that can be used in methods of the present invention. Similarly the pre-cast shapes shown in Figure 6 are suitable for use in this invention. Figure 7 illustrates more complex layout in which the column shells 1 are pre-formed with specific spigotted ends that increase the strength of the in-situ joint formed when carrying out the described method.

By using this invention, it is possible to build a complete three dimensional pre-cast framed structural building system using in-situ wet joints to form rigid connections between pre-cast column shells and pre-cast beams.

The invention has been given by way of example only, and various (other) modifications of and/or alterations to the described embodiments may be made by persons skilled in the art without departing from the scope of the invention as specified in the appended claims.

Claims

1. A method of making a structural joint for a building comprising positioning a first pre-cast column shell vertically, casting concrete in the column shell to a level below the top of the column shell, temporarily supporting or forming at least one lateral support beam with its end adjacent the top of the first column shell, placing a second pre-cast column shell with its bottom end above and in line with the top end of the first column shell, and securing the at least one support beam to the column shells by means of in-situ reinforced concrete that is flowed around the said ends of the first and second column shells to form a collar and which fills up the top of the first column shell and at least a bottom part of the second column shell.

2. A method according to claim 1, including temporarily supporting an at least one pre-cast floor beam by a steel frame removably fixed to an outside of the first column shell adjacent the top thereof.

3. A method according to claim 1 or 2, in which the concrete is flowed to fill the second column shell to generally adjacent but below the top of the second column shell.

4. A method according to any of claims 1 to 3, including providing formwork to form a lateral tie beam with its one end adjacent the top of the first column shell, and forming the tie beam or part of it using the in-situ reinforced concrete that is flowed around the said ends of the column shells.

5. A method according to any of claims 1 to 4, including securing pre-cast floor planks using the flowed in-situ reinforced concrete.

6. A method according to any of claims 1 to 5, including fixing free ends of reinforcement in position and/or reinforcements placed within the in-situ joint cavities before flowing the concrete around the column shell ends.

7. Methods of making structural joints in building substantially as herein described with reference to the accompanying drawings.