MASONRY WITH VERTICAL REINFORCED CONCRETE STRENGTHENING
A masonry infill in a load bearing structure (18), comprises courses of hollow masonry units (1) arranged to define a cavity (3) extending therethrough filled with reinforced cementitious material e.g. reinforced concrete. A lower end of the concrete reinforcement (2) is secured to a load bearing support (16, FIG. 3). A body (6) is secured to the load bearing structure and receives an upper end of the concrete reinforcement so as to permit longitudinal sliding movement of the reinforcement upper end in the body, whilst constraining movement of the concrete reinforcement in a direction transversely of the infill The lower end of the reinforcement (2) may be built into the support, or slidably received in a further body (5, FIG. 3). Alternatively one or both ends of the reinforcement (2) may terminate in a bond beam. Brackets (9, 9a) may be embedded in the concrete in the cavity (3) to transfer shear forces between the adjacent blockwork and the concrete.
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Current techniques for constructing larger buildings usually involve the use of a load bearing frame of steel or reinforced concrete, with attached cladding and/or masonry infills. In the case of masonry walls in such structures and elsewhere, it is necessary to provide additional strengthening where the area of the wall increases beyond certain limits. The strengthening is required to support the weight of the wall; to resist environmental loading such as wind forces, differences in air pressure and earthquakes; as well as to withstand other dynamic service loads such as crowd pressure, vehicle impact or explosions. The required strength for a given structure is governed not only by the laws of physics but also by local building regulations.
Traditionally where additional strength is needed, walls have been supported by cross walls, piers and areas of wall thickening. More recently windposts have been developed, which are used in most building walls (particularly interior walls), if their length exceeds 4 m. The purpose of the windpost is to stiffen or strengthen the walling, in circumstances of particular lateral stress from wind induced pressure differences, crowd or other design loads. A windpost generally consists of a steel column secured at its top and base to the building frame or another suitable load-bearing structure. This form of construction brings with it the following disadvantages:
1. An expansion joint is required on either side of the windpost, where it interfaces with the adjacent masonry. Filler material is inserted between the post and the masonry block faces to form the joint.
2. Frame ties typically at 225 mm centres must be provided between the masonry and the post on both sides.
3. Mastic will often be a specification requirement.
4. The windpost will require fire protection.
5. Loss of acoustic and thermal insulation.
6. The windpost typically requires four bolt fixings, two at the base and two at the soffit.
7. The windpost must be erected before the walling and so isolated access (e.g. scaffolding) is required for safe work practice particularly at height.
Our invention seeks to replace the windpost and to achieve increased strength and ductility within the wall panel.
SUMMARY OF THE INVENTIONAccording to the invention, there is provided a masonry infill in a load bearing structure, comprising hollow masonry units arranged to define a cavity extending through adjacent courses thereof, the cavity being filled with reinforced cementitious material, a lower end of the cementitious material reinforcement being secured to a load bearing support; a body being secured to the load bearing structure and receiving an upper end of the cementitious material reinforcement so as to permit longitudinal sliding movement of the reinforcement upper end in the body, whilst constraining movement of the reinforcement in a direction transversely of the infill.
The reinforced cementitious material strengthens the masonry infill against transverse loading/deflection and helps to secure the panel within the load bearing structure. The reinforced cementitious material (e.g. reinforced concrete) also helps to transmit transverse loads applied to the masonry to the load bearing structure above and the load bearing support below.
The load bearing support may be a foundation, or another part of the load bearing structure, for example a beam. The body may be secured to or within a beam which forms a part of the load bearing structure above or within the masonry infill.
On their exterior, the masonry course or courses containing the cementitious material are indistinguishable from the adjacent masonry. This can have aesthetic advantages. The reinforced cementitious material may be used instead of a wind post, without requiring expansion joints frame ties, mastic, fire protection, sound insulation or dedicated isolated access during construction.
The reinforcing material may comprise steel bar (e.g. “rebar”). The optimum or acceptable relative section areas of the concrete and steel and the positioning of the bars in the cavity may be calculated in accordance with standard engineering principles for beams and columns subjected to point and/or distributed loading, taking into account design service conditions such as anticipated impact and wind loading, etc. The reinforced cementitious material will key to the interiors of the hollow blocks and their presence can therefore be taken into account when determining the size and position of the steel bars. Allowance must be made for any reduction in compressive strength caused by the presence of any mortar joints in the masonry. The masonry is preferably laid in mortar or like bonding/bedding material. Solid masonry units may be used in regions of the masonry infill away from the cavity.
In similar manner to the upper end, the lower end of the cementitious material reinforcement may be received in a body secured to the load bearing support so as to permit longitudinal sliding movement of the reinforcement lower end in the body, whilst constraining movement of the reinforcement in a direction transversely of the infill. Alternatively the lower end of the cementitious material reinforcement may be built into the load bearing support, e.g. fixed in concrete forming the load bearing support.
The body may comprise a socket in which the end (upper or lower, as applicable) of the cementitious material reinforcement is received. Where the load bearing structure or load bearing support is formed from concrete, the socket may be formed in a metal body inserted (e.g. cast) into the load bearing structure/support. Where the load bearing structure or load bearing support is a metal (e.g. steel) frame, the socket may be formed in a cleat secured (e.g. bolted) to the frame.
The cementitious material reinforcement may be a sliding fit in the socket (e.g. there may be a total radial clearance of 1 mm or less for a rebar of 16 mm diameter). This allows relative longitudinal movement to take place between the cementitious material reinforcement and the socket, thereby accommodating differential expansion between the masonry infill and the load bearing structure. Suitable boots, seals or sealant may be applied to prevent the wet cementitious material from entering the socket as the reinforced cementitious material is cast. Under transverse loading of the masonry, the reinforcing bar ends engage the interior sides of the sockets and transfer the transverse loads to the load bearing structure. Under such loading, the bond beam and reinforcing bars will tend to bowso as to produce a reactive moment at the socket. Reaction forces from the sockets at the bar ends and the stiffness of the bond beam and surrounding masonry tend to restrain and prevent excessive lateral movement of the masonry.
The upper course or edge of the masonry infill may be secured to the load bearing structure by other means besides the attachment at the reinforcement. Fixings which are conventional in themselves, such as metal brackets and head restraints, can be used for this purpose. Mortar beds between courses may also be reinforced by means which are conventional as such, for example using metal wire or mesh.
Additionally or alternatively, reinforcements such as rebars or suitably shaped elongate metal brackets may be embedded in the cementitious material in the cavity, with one or both of their ends extending into the masonry bed joints. For example, such brackets or reinforcements may extend to one side, to both sides, or to either side alternately, of the cavity, in each course, in every other course, in every third course, etc, depending upon the degree of reinforcement demanded by the particular service conditions of the masonry infill concerned.
More than one reinforced cementitious material filled cavity as described above can be provided, thereby providing effective reinforcement of horizontally long masonry infills, or at free vertical edges of apertures formed in a masonry infill.
The cementitious material reinforcement may comprise shorter lengths secured together end-to-end or overlapped to provide effective longitudinal securement, so that the hollow masonry units do not have to be threaded over the entire length of the reinforcement as the infill is constructed. The first length of the cementitious material reinforcement is secured to the load bearing support, and further lengths are added upwardly as the infill is built up. The cavity can be filled with cementitious material to encase the reinforcement as each masonry course is laid; or after two or more courses have been laid; or after the entire infill is otherwise complete. It is preferred that the cementitious material is not allowed to fully cure between successive pours, to eliminate cold jointing and promote bonding into a unitary whole. Threaded connections can be used to secure the lengths of cementitious material reinforcement end-to-end, but generally the overlapping securing method is preferred.
The masonry infill may also comprise a reinforced cementitious material (e.g. concrete) casting extending parallel to a course of masonry units. For example the reinforced cementitious material casting may comprise a bond beam formed within a course of hollow masonry units. These units may have a U-shaped cross-sectional profile within which the reinforcement (e.g. rebars) is placed, and within which the cementitious material of the bond beam is contained whilst it cures and afterwards. One or both ends of the reinforcement for the casting may be secured to the load bearing structure. Bodies secured to the load bearing structure in a similar manner to those used to secure the upper end of the above-described cementitious material reinforcement, may be used to secure the or each end of the cementitious material casting to the load bearing structure.
One or more courses of masonry above and/or below the cementitious material of the bond beam may be tied into the cementitious material by reinforcements extending into the cementitious material and into mortar filled spaces in or between the units of masonry in these courses. For example, rebar or suitably shaped elongate metal brackets may be cast into the cementitious material so as to extend into the vertical mortar joints (perpends or “perps”) in the adjacent course or courses above and/or below. Where the cementitious material is cast in the gap between the limbs of a U-cross-sectioned block, selected U-shaped blocks may be provided with holes in their bases, allowing the rebar or elongate brackets to pass downwardly into perpends of the course below, as well as upwardly from between the limbs of the U into the course above. The rebar or brackets may be assembled from shorter lengths joined end-to-end as building of the infill progresses, in similar way to the advantageous form of cementitious material reinforcement described above. In this way, the rebars or brackets may extend through and tie several courses of masonry above and/or below to the cementitious material casting or bond beam. Where the rebars or brackets pass through these courses in regions away from perpends, they may be grouted or mortared into vertical holes running through the masonry units concerned. The elongate brackets may be generally L-shaped, having a horizontal support foot which rests against the blockwork course below and stabilses the bracket against an adjacent block before it is built into the masonry.
It has been found that the reinforced cementitious material filled cavity running through masonry courses and with reinforcement ends secured to a load bearing support and load bearing structure as previously described, and/or the reinforced cementitious material casting extending parallel to the course of masonry units and having upwardly and/or downwardly extending rebars or brackets, as described above, both serve to resist crack propagation when the masonry infill is subjected to transverse loading.
In a further independent aspect, the invention therefore provides a reinforced cementitious material casting extending parallel to a course of masonry units, in which one or more courses of masonry above and/or below the reinforced cementitious material casting are tied thereto by reinforcements extending into the cementitious material and into grout or mortar filled spaces in or between the units of masonry in these courses, the reinforcements being formed from separate lengths with ends overlapped, or joined end to end, for example joined by threaded connections.
The invention correspondingly provides a method of constructing a masonry infill in a load bearing structure, the method comprising the steps of:
laying hollow masonry units to define a cavity extending through adjacent courses of the masonry infill and filling the cavity with reinforced cementitious material,
wherein a lower end of the cementitious material reinforcement is secured to a load bearing support;
a body is secured to the load bearing structure; and
an upper end of the cementitious material reinforcement is longitudinally slidably received in the body in use; the body constraining movement of the reinforcement in a direction transversely of the infill.
Further features and advantages of the invention will be apparent from the following description of illustrative embodiments made with reference to the accompanying schematic drawings.
The structure shown in
As shown in
However, to reduce the overall number of parts required in constructing a variety of reinforced blockwork walls, the bracket 9a may be of a generally standardised form as shown on
The standard bracket 9a can also be used as a stress transfer member in a bond beam, as shown in
Claims
1. A masonry infill in a load bearing structure, the masonry infill comprising;
- a plurality of hollow masonry units arranged to define a cavity extending through adjacent courses of the masonry infill, the cavity being filled with a cementitious material;
- cementitious material reinforcement extending through the cavity and having a lower end which is secured to a load bearing support;
- a first body secured to the load bearing structure and receiving an upper end of the cementitious material reinforcement so as to permit longitudinal sliding movement of the upper end in the first body while constraining movement of the cementitious material reinforcement in a direction transversely of the masonry infill.
2. A masonry infill as defined in claim 1, wherein the load bearing support comprises a foundation.
3. A masonry infill as defined in claim 1, wherein the load bearing support comprises a part of the load bearing structure.
4. A masonry infill as defined in claim 1, wherein the first body is secured to a beam which forms a part of the load bearing structure above the masonry infill.
5. A masonry infill as defined in claim 1, wherein the lower end of the cementitious material reinforcement is received in a second body secured to the load bearing support so as to permit longitudinal sliding movement of the lower end in the second body whilst while constraining movement of the cementitious material reinforcement in a direction transversely of the masonry infill.
6. A masonry infill as defined in claim 1, wherein the lower end of the cementitious material reinforcement is built into the load bearing support.
7. A masonry infill as defined in claim 1, wherein the first body comprises a socket in which the upper end of the cementitious material reinforcement is received.
8. A masonry infill as defined in claim 7, wherein the first body is inserted into the load bearing structure.
9. A masonry infill as defined in claim 7, wherein the first body comprises a cleat.
10. A masonry infill as defined in claim 7, wherein the cementitious material reinforcement is a sliding fit in the socket.
11. A masonry infill as defined in claim 7, further comprising one from the group consisting of a boots, a seals or a sealant to prevent material from entering the socket as the cementitious material is cast.
12. A masonry infill as defined in claim 1, further comprising means for securing an uppermost course of the masonry infill to the load bearing structure.
13. A masonry infill as defined in claim 1, further comprising a reinforced cementitious material casting extending parallel to a course of the masonry units.
14. A masonry infill as defined in claim 13, wherein the reinforced cementitious material casting comprises a bond beam formed within a course of hollow masonry units.
15. A masonry infill as defined in claim 13, wherein the casting comprises a reinforcement having at least one end which is secured to the load bearing structure.
16. A masonry infill as defined in claim 13, wherein one or more courses of masonry units vertically adjacent the casting are tied into the cementitious material by a number of tying reinforcements extending into the cementitious material and into mortar or grout filled spaces in or between the masonry units of the vertically adjacent courses.
17. A masonry infill as defined in claim 16, wherein the tying reinforcements comprise lengths of the cementitious material reinforcement.
18. A masonry infill in a load bearing structure the masonry infill comprising:
- a plurality of hollow masonry units arranged to define a cavity extending through adjacent courses thereof, the cavity being filled with a cementitious material; and
- a cementitious material reinforcement extending through the cavity and having an end which is secured to a bond beam formed within the masonry infill.
19. A masonry infill as defined in claim 1, wherein the cementitious material reinforcement is comprised of steel.
20. A masonry infill as defined in claim 1, wherein the masonry is units are laid in a bonding/bedding material.
21. A masonry infill as defined in claim 1, further comprising a plurality of solid masonry units which are located in regions of the masonry infill spaced apart from the cavity.
22. A masonry infill as defined in claim 1, further comprising a number of tying reinforcements embedded in the cementitious material in the cavity, each tying reinforcement comprising a projecting end extending into a masonry bed joint.
23. A masonry infill as defined in claim 1, wherein the cementitious material reinforcement comprises a plurality of separate lengths co-operating to carry tensile loads.
24. A masonry infill as defined in claim 23, wherein adjacent ends of the lengths are secured together by threaded connections.
25. A masonry infill as defined in claim 23, wherein adjacent ends of the lengths are overlapped.
26. A masonry infill as defined in claim 1, wherein the cavity runs adjacent to a vertically extending free edge of an opening formed in the masonry infill.
27. A reinforced cementitious material casting extending parallel to a course of masonry units wherein one or more courses of masonry units vertically adjacent the cementitious material casting are tied thereto by reinforcements extending into the cementitious material and into grout or mortar filled spaces in or between the units of masonry in these courses, the reinforcements being formed from separate lengths with ends overlapped or joined end to end.
28. A method of constructing a masonry infill in a load bearing structure, the method comprising the steps of:
- laying hollow masonry units to define a cavity extending through adjacent courses of the masonry infill;
- positioning a cementitious material reinforcement in the cavity;
- securing a lower end of the cementitious material reinforcement to a load bearing support;
- securing a body to the load bearing structure; and
- filling the cavity with a cementitious material;
- wherein an upper end of the cementitious material reinforcement is longitudinally slidably received in the body to constrain movement of the reinforcement in a direction transversely of the infill.
Type: Application
Filed: Feb 4, 2009
Publication Date: Dec 30, 2010
Applicant: WEMBLEY INNOVATION LTD. (LONDON)
Inventor: Liam Clear (London)
Application Number: 12/735,668
International Classification: E04B 1/04 (20060101); E04B 1/20 (20060101); E04G 21/20 (20060101);