7.01 mabey hire services limited | 01924 460 601 | www.mabeyhireservices.com groundworks technical reference | section 7: proprietary bracing struts proprietary bracing struts HDMBS (10kN accidental load) MBS (with screws extended less than 300mm + 10kN accidental load) MBS (with screws extended less than 450mm + 10kN accidental load) MBS (no restriction on screw extension + 10kN accidental load) JC40 (5kN accidental load) LMBS (10kN accidental load) 200 100 2 1 0 3 4 5 6 7 8 9 10 11 12 13 300 400 500 600 700 safe working load (kN) length (m) combination with double-acting hydraulic bracing frames for the strutting of excavations. The most commonly used struts are: • JC40 bracing strut - originally developed for use in trench boxes • light duty mechanical bracing strut (LMBS) • standard mechanical bracing strut (MBS) • standard mechanical bracing strut with higher strength screw units - normally referred to as heavy duty mechanical bracing strut (HDMBS) • super bracing strut (SBS) All the struts are modular with mechanical screw adjustment so they are not at risk of hydraulic failure. The prop bodies for light duty mechanical, standard mechanical and super bracing struts consist of square sections as opposed to circular sections for safer handling and storage on site and during transportation - the square section bodies minimise the risk of rolling. For chart below: Similar information in tabular form appears on pages 7.03, 7.05, 7.06 and 7.07. For information on the super bracing strut see pages 7.08 onwards. Proprietary Bracing Struts - Allowable Loads (except Super Bracing Struts - see page 7.10)
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7.01
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section 7
: p
rop
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racin
g s
truts
proprietary bracing struts
HDMBS (10kN accidental load)
MBS (with screws extended less than 300mm + 10kN accidental load)
MBS (with screws extended less than 450mm + 10kN accidental load)
MBS (no restriction on screw extension + 10kN accidental load)
JC40 (5kN accidental load)
LMBS (10kN accidental load)200
100210 3 4 5 6 7 8 9 10 11 12 13
300
400
500
600
700
safe
wor
king
load
(kN
)
length (m)
combination with double-acting hydraulic bracing frames for the strutting of excavations. The most commonly used struts are:
• JC40 bracing strut - originally developed for use in trench boxes
• light duty mechanical bracing strut (LMBS)
• standard mechanical bracing strut (MBS)
• standard mechanical bracing strut with higher strength screw units - normally referred to as heavy duty mechanical bracing strut (HDMBS)
• super bracing strut (SBS)
All the struts are modular with mechanical screw adjustment so they are not at risk of hydraulic failure.
The prop bodies for light duty mechanical, standard mechanical and super bracing struts consist of square sections as opposed to circular sections for safer handling and storage on site and during transportation - the square section bodies minimise the risk of rolling.
Forchart below:
Similar information in tabular form appears on pages 7.03, 7.05, 7.06 and 7.07.For information on the super bracing strut see pages 7.08 onwards.
Proprietary Bracing Struts - Allowable Loads(except Super Bracing Struts - see page 7.10)
The above struts are intended to sustain allowable axial compression loads as shown on page 7.01. Similar performance data in tabular form is set out on pages 7.05, 7.06 and 7.07.
Performance Criteria1. The allowable axial compression loads are based on:
a) relevant parts of BS449 : 1969 : Part 2 b) testing
2. The performance data assumes that the make-up of the struts is in accordance with the user information
in particular:
a) The struts are used in combination with one of Mabey Hire Services’ Universal Column waler rails, i.e. U.C. 203x203x52kg/m Shaftbrace rail (LMBS and MBS struts only) U.C. 254x254x107kg/m Multibrace rail U.C. 254x254x107kg/m Super Shaftbrace rail
b) The strut is connected with the correct connector plate and clamp arrangement such that the centre-line of the strut is aligned with the web of the waler rail and end restraint is provided.
c) The st
3) The performance data below allows for:
a) Axial loading in combination with primary bending due to self weight
b) An accidental load imposed at any point along the strut equivalent to a static point load of 10kN as recommended in CIRIA Special Report 95 (December 1993).
c) Secondary moments resulting from:
• eccentricity of axial load • an allowance for accumulation of debris on the strut • an allowance for initial strut crookedness