CI/SfB Et6 BALCON TM STEEL BALCONY CONNECTION SYSTEM

Transcription

1 CI/SfB Et6 BALCON TM STEEL BALCONY CONNECTION SYSTEM

2 Introduction Balconies, whether steel or concrete, are a common feature of residential developments - providing much desired outdoor space and additional living area. The connection of steel balconies to concrete floor slabs (normally involving separate trades) in particular, gives rise to a special set of practical and design considerations, namely, the need to: Where the floor slab is laid by the concrete frame contractor and the balcony often connected by a subsequent contractor, any problems of alignment can then lead to contractual conflict. 1. Carry high loads. 2. Minimise the adverse effects of cold-bridging. 3. Provide considerable adjustability in the fixing method. Fig.2 The BALCON steel balcony connection system (Fig.2) provides the ideal solution. Manufactured using highload carrying JORDAHL cast-in channels, BALCON offers multi-directional adjustment. The system can be purpose-made to each application and can even be configured to accommodate retro-fit balcony installations (e.g. for refurbishment projects). As can be seen in the above image, to provide some adjustment, multiple holes have been drilled and threaded rods inserted, which then protrude from the slab edge. Such drastic methods lead to the need for extensive site surveys and retro-drilling; adding cost, as well as introducing health and safety risk to the project. Thermal Assessment 2 Fig.1 Any system of connection to a fixed point in the floor slab (even applicable to most proprietary balcony connection systems), means that any small error in installation (into the floor slab) leaves the contractor totally reliant on the minimal level of adjustment available in the balcony stub-bracket (Fig.1). Due to the nature of its construction, the prospect of cold-bridging is minimal. BALCON has been thermally assessed by the BBA (British Board of Agrément) and exceeds the values acceptable for minimisation of risk of internal surface condensation in dwellings, residential buildings and schools as set out in the BRE Information Paper IP/06 Assessing the effects of thermal bridging at junctions around openings. See page 7 for optional inclusion of Fabreeka isolation pads.

3 How BALCON TM works The BALCON system comprises three lengths of JORDAHL hot-rolled anchor channels; one being horizontal and plain-lipped (Fig. 1) to which are welded two lengths of toothed channel (Fig. 2) set vertically, all with matching JORDAHL T-bolts. The channels have appropriate lengths of grade 500 reinforcement welded to the back and sides (Fig. 3) to provide full anchorage into the concrete floor slab. Fig.1 Fig.2 Fig. 3 Shear load (up to a maximum factored value of 75.6 kn) is taken by the vertical channels which incorporate shear-resisting teeth. See additional information on page 4. Moment load (to a maximum factored value in excess of 60 knm) is taken by tension in the top/horizontal channel and compression against the vertical channels. See additional information on page 4. As illustrated below, BALCON provides an unrivalled degree of installation tolerance in all directions including rotational. BALCON is therefore the most forgiving of all proprietary balcony connection systems, even when poorly installed (please contact J&P if in doubt regarding incorrect alignment). BALCON TM correctly positioned. Vertical tolerance. Horizontal & vertical tolerance. Rotational tolerance. 3

4 How to specify BALCON TM The BALCON system is available in three principal configurations; BALCON-2, BALCON-3 and BALCON-4. The 2, 3 and 4 relates simply to the number of T-bolts employed in the horizontal channel sections, which increase in profile from W*40/22 (mm) to W*72/48 (mm) to accommodate incremental moment loads (factored) in excess of 60 knm (*W indicates hotrolled channel). Shear load is taken by the pair of vertical, toothed channels. For normal balcony shear conditions, each pair of vertical channels (with a singular, toothed T-bolt in each) has a factored capacity of 33.6 kn. For abnormally high shear loads, BALCON units can be configured with vertical channel sections having a factored shear capacity as high as 75.6 kn. To determine the appropriate BALCON type, the desired moment needs to be pre-calculated, then: 1. Take the slab thickness and deduct 80mm, which will define the lever arm to be used in the graphs on these pages. 2. Plot a vertical line at this point on the graph for BALCON Using the pre-calculated moment, plot a horizontal line across the graph. Result: If the two plotted lines intersect at any point where a coloured zone occurs, then a BALCON-2 solution exists. However, if the intersect occurs in blank/white space, try again by moving onto the BALCON-3, then BALCON-4 graphs. Worked example Assume a 300mm slab with a factored balcony moment (at the slab edge) of 27.5 knm. The lever arm is calculated as =220mm. Plot the resultant intersect on the BALCON-2 graph (see dashed line) and you will observe a negative result. However, plot the same data on the BALCON-3 graph (see dashed line) and a positive result is achieved as the intersect occurs within the coloured zone for the W55/42 profile. The resultant specification is therefore; BALCON-3-W55/42. Note: Using the graphs, alternative solutions may also be found, e.g. using the same data as the above worked example, results can also be found on the BALCON-4 graph e.g. BALCON-4-W53/34 or BALCON-4-W55/42 - both of which utilise an additional bolt. From a cost-efficiency perspective, there s little to choose between these options and the first-found BALCON-3-55/42 solution. All work and all provide identical application tolerance. The design graphs on these pages are provided for preliminary sizing and specification purposes. Application-specific design data and specifications can be provided on request Balcon-2 Moment (knm) W72/48 W55/42 W53/34 W50/30 W40/ Lever Arm (mm) 4 Standard shear capacity 33.6kN

5 How to specify BALCON TM Moment (knm) Balcon-3 W72/48 W55/42 W53/34 W50/30 W40/ Lever Arm (mm) Standard shear capacity 33.6kN Balcon-4 Moment (knm) W72/48 W55/42 W53/34 W50/30 W40/ Lever Arm (mm) Standard shear capacity 33.6kN 5

6 BALCON TM project examples BALCON has been successfully used on numerous keynote projects throughout the UK. Here are just a few examples. London 2012 Olympics Athletes Village Woodberry Down, London Media City UK, Manchester 6

7 BALCON TM related products To complement BALCON, J&P offer a number of associated solutions for the building envelope and frame. Fabreeka structural thermal-break connection pads The BALCON system, in its standard guise, has been thermally assessed by the BBA (British Board of Agrément) and exceeds the values acceptable for minimisation of risk of internal surface condensation in dwellings, residential buildings and schools as set out in the BRE Information Paper IP/06 Assessing the effects of thermal bridging at junctions around openings. Optionally, to satisfy designers seeking further enhanced thermal performance, J&P can provide Fabreeka isolation pads (Fig. 1), which are positioned between the balcony stub bracket and the slab edge/ channel lips. ISOPRO insulated balcony connections Whereas BALCON addresses the connection of steel balconies to concrete floor slabs, ISOPRO addresses the structural connection of concrete balconies and walkways, whilst maintaining a thermal break. Manufactured by J&P parent company, H-BAU, the ISOPRO system (Fig. 2) is an internationally proven system for minimising the effects of cold-bridging and solves a wide range of load and geometrical conditions. Fig.2 BEAMCON steel beam connection system Fig.1 Following the same design principles as BALCON, the BEAMCON solution from J&P (Fig.3) is also derived from high-load carrying JORDAHL cast-in channels. BEAMCON provides similar fixing tolerance for the connection of structural steel sections to the concrete frame. It also helps resolve any potential misalignment between the steel and concrete trades. Fig.3 7

8 Focused on construction solutions for keynote projects in the UK and Worldwide BALCON TM Adjustable and insulated steel balcony connections ISOPRO Insulated concrete balcony connections JTA ANCHOR CHANNEL For adjustable curtain wall connections PENTAFLEX Concrete waterproofing systems COLUMN SHOES High-load connections for precast columns JDA Punching shear reinforcement for concrete columns RVK/TSS Invisible connections for precast stair landings JSD+ Shear dowels for concrete movement joints FERBOX Reinforcement continuity strip for in-situ connections RAPIDOBAT Seamless column formwork for quality architectural concrete J&P Building Systems Limited Thame Forty, Jane Morbey Road, Thame, Oxfordshire OX9 3RR JP/PI/BA/0913