JGJT231-2021 PDF English
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Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
JGJ/T 231-2021 | English | 1405 |
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Technical standard for safety of disk lock steel tubular scaffold in construction
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JGJ/T 231-2021: Technical standard for safety of disk lock steel tubular scaffold in construction ---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/JGJT231-2021
UDC JGJ
NATIONAL STANDARD OF THE
PEOPLE��S REPUBLIC OF CHINA
P JGJ/T 231-2021
Replacing J 1128-2021
Technical standard for safety of disk lock steel tubular
scaffold in construction
Issued on. JUNE 30, 2021
Implemented on. OCTOBER 01, 2021
Issued by. Ministry of Housing and Urban-Rural Development of the People's
Republic of China
NATIONAL STANDARD OF THE
PEOPLE��S REPUBLIC OF CHINA
Technical standard for safety of disk lock steel tubular
scaffold in construction
Approved by. Ministry of Housing and Urban-Rural Development of the People's
Republic of China
Implemented on. OCTOBER 1, 2021
2021 Beijing
Table of Contents
Foreword... 4
1 General provisions... 7
2 Terms and symbols... 7
2.1 Terms... 7
2.2 Symbols... 9
3 Basic requirements... 12
4 Loads... 13
4.1 Load classification... 13
4.2 Characteristic value of loads... 14
4.3 Subentry coefficient of loads... 16
4.4 Combination of loads effects... 17
5 Structural designs... 18
5.1 General requirements... 18
5.2 Foundation bearing capacity calculation... 20
5.3 Calculation of shoring scaffold... 21
5.4 Calculation of operation scaffold... 23
5.5 Calculation of component... 26
6 Construction requirements... 27
6.1 General requirements... 27
6.2 Shoring scaffold... 27
6.3 Operation scaffold... 32
7 Installation and disassembly... 34
7.1 Preparation for construction... 34
7.2 Construction scheme... 35
7.3 Ground and foundation... 35
7.4 Installation and disassembly of shoring scaffold... 36
7.5 Installation and disassembly of operation scaffold... 37
8 Inspection and acceptance... 39
9 Safety management and maintenance... 41
Annex A Calculating Coefficients of Wind Load... 43
Annex B Design parameters... 45
Annex C Stability coefficients for axial compression components... 46
Annex D Construction acceptance record sheets for scaffold... 48
Explanation of wording in this Standard... 52
List of quoted standards... 53
Technical standard for safety of disk lock steel tubular
scaffold in construction
1 General provisions
1.0.1 This Standard is formulated to ensure that the design, installation, dismantling,
use and management of disk lock steel tubular scaffold are technologically advanced,
economically reasonable, safe and applicable.
1.0.2 This Standard applies to the design, installation, dismantling, use and management
of disk lock steel tubular scaffold in construction and municipal engineering.
1.0.3 In addition to complying with this Standard, the design, installation, dismantling,
use and management of disk lock steel tubular scaffold shall also comply with the
provisions of relevant national standards.
2 Terms and symbols
2.1 Terms
2.1.1 disk lock steel tubular scaffold
According to the purpose of use, it can be divided into shoring scaffold and operation
scaffold. A structural frame that can withstand corresponding loads and has operational
safety and protection functions, in which the standards are connected by outer tube or
inner tube, ledgers and diagonal braces are snapped into the connecting plate by the use
of rod end ledger or diagonal brace end, connected with wedges, is referred to as a
scaffold.
2.2 Symbols
2.2.1 Loads and load effects
FR - Design value of vertical force acting on the connecting plate;
MR - Anti-overturning moment of the scaffold under the design load;
MT - Overturning moment of the scaffold under the design load;
Mw - Bending moment due to wind load design value;
Mwk - Bending moment caused by characteristic value of wind load;
N - Design value of standard��s axial force;
N0 - Axial force generated by the out-of-plane deformation of the scaffold due to the
constraints of the anchoring;
Nk - Standard combination value of the axial force transmitted from the standard to the
top surface of the foundation;
Nl - Design value of axial force of anchoring;
Nlw - Design value of axial force of anchoring s caused by wind load;
3 Basic requirements
3.0.1 According to the outer diameter of the standard, scaffold can be divided into
standard type (type B) and heavy duty (type Z). Scaffold components, materials and
production quality shall comply with the current industry standard "Disk lock steel
tubular scaffold components" JG/T 503.
3.0.2 The wedge connection between the rod ledger or diagonal brace end and the
connecting plate shall not be pulled out after hammering and self-locking. When
erecting scaffold, it is recommended to hit the top surface of the wedge no less than 2
times with a hammer of no less than 0.5 kg until the wedge is tight.
3.0.3 After the wedge is tightened, the arc surface at the end of the ledger or diagonal
brace end shall fit with the outer surface of the standard.
3.0.4 Scaffold structure design shall adopt different safety levels according to the type
of scaffold, height of shoring scaffold and load. The classification of scaffold safety
levels shall comply with the provisions of Table 3.0.4.
4 Loads
4.1 Load classification
4.1.1 The loads acting on scaffolds can be divided into permanent loads and variable
loads.
4.1.2 The permanent load of the shoring scaffold shall include the following.
4.1.3 The permanent load of the operation scaffold shall include the self-weight of the
frame and components, including the self-weights of standards, ledgers, diagonal braces,
base jacks, head jacks, scaffold boards, railings, toe boards, stairs, safe nets.
4.2 Characteristic value of loads
4.2.1 The characteristic value of the permanent load of the shoring scaffold shall comply
with the following regulations.
4.2.5 The characteristic value of the variable load of the operation scaffold shall comply
with the following regulations.
4.3 Subentry coefficient of loads
4.3.1 When calculating the strength, stability and node connection strength of scaffold
components, the load design value shall be multiplied by the load characteristic value
multiplied by the load subentry coefficient. The value of the load subentry coefficient
shall comply with the provisions of Table 4.3.1.
4.4 Combination of loads effects
4.4.1 Scaffold design shall be based on the load conditions that may occur during
normal erection and use. Load combinations shall be carried out according to the load-
bearing capacity limit state and the normal service limit state. The most unfavorable
load combinations shall be selected for design.
4.4.2 For the limit state of bearing capacity, the basic combination of load effects shall
be adopted. For normal service limit states, the load effect standard combination shall
be used.
5 Structural designs
5.1 General requirements
5.1.1 The structural design of scaffold shall be based on the current national standards
"Load code for the design of building structures" GB 50009, "Code for Design of Steel
Structure" GB 50017, "Technical code of cold-formed thin-wall steel structures" GB
50018 and "Unified standard for reliability design of building structures" GB 50068.
The probabilistic limit state design method is adopted. Use the design expression of
subentry coefficient.
5.1.4 When the shoring scaffold is erected in the form of an independent square tower
with vertical diagonal braces in both directions (Figure 5.1.4), the calculation and
analysis can be performed in the form of a lattice column structure with diagonal web
rods.
5.2 Foundation bearing capacity calculation
5.2.1 The bottom foundation bearing capacity of the base jack shall meet the
requirements of the following formulas.
5.3 Calculation of shoring scaffold
5.3.1 The design value of the axial force of the standard shall be calculated according
to the following formula.
5.4 Calculation of operation scaffold
5.4.1 When there is no wind load, the calculation of the bearing capacity of the standard
shall comply with the following regulations.
5.5 Calculation of component
5.5.1 The shear bearing capacity of the connecting plate of the disk lock node shall meet
the requirements of the following formula.
5.5.2 When the side bracket is used to resist external effects, the bearing capacity shall
be calculated. When checking the bearing capacity of the standard, the additional
bending moment generated by the side bracket shall be taken into account.
6 Construction requirements
6.1 General requirements
6.1.1 The structural system of the scaffold shall be complete. Scaffold shall have overall stability.
6.1.2 Ledgers and diagonal braces of fixed length shall be selected according to the
vertical and horizontal spacing of standards calculated according to the construction
plan. The standard, base collar, head jack and base jack shall be combined according to
the height of shoring scaffold.
6.1.3 The lift height of the shoring scaffold shall not exceed 2 m.
6.2 Shoring scaffold
6.2.1 The aspect ratio of the shoring scaffold shall be controlled within 3.Shoring
scaffolds with an aspect ratio greater than 3 shall take anti-overturning measures such
as rigid connection with existing structures.
6.3 Operation scaffold
6.3.1 The aspect ratio of the operation scaffold shall be controlled within 3.When the
aspect ratio of the operation scaffold is greater than 3, anti-overturning measures such
as support or cable wind ropes shall be installed.
6.3.2 When erecting a double-row external operation scaffold or when the height of
shoring scaffold is 24 m or above, the geometric dimensions of the frame shall be
selected according to the usage requirements. The lift height between adjacent ledgers
shall not be greater than 2 m.
6.3.7 Where the side bracket is connected and in contact with the standard, a ledger
shall be added along the length of the side bracket. Adjacent side brackets shall be
firmly connected.
7 Installation and disassembly
7.1 Preparation for construction
7.1.1 Before scaffold construction, a special construction plan shall be prepared based
on the construction site conditions, foundation bearing capacity, and height of shoring
scaffold, and shall be implemented after review and approval.
7.2 Construction scheme
7.2.1 The special construction scheme shall include the following contents.
7.3 Ground and foundation
7.3.1 The scaffold foundation shall be constructed according to a special construction
plan. It shall be inspected and accepted according to the foundation bearing capacity
requirements. The scaffold shall be erected after the foundation has been inspected and
accepted.
7.5 Installation and disassembly of operation scaffold
7.5.1 The operation scaffold standards shall be accurately positioned and erected in
accordance with the construction progress. The height of shoring scaffold of the double-
row external work rack shall not exceed two steps of the uppermost anchoring at one
time. The free height shall not be greater than 4 m.
7.5.2 The anchoring of the double-row external operation scaffold shall rise with the
height of the scaffold. Synchronize settings at specified locations. Delayed installation
and arbitrary dismantling are not allowed.
7.5.6 When the standard is in tension, the casing connection extension of the standard
shall be connected with bolts.
7.5.7 Operation scaffolds shall be erected and used in sections. They shall be inspected
and accepted before use.
7.5.8 The operation scaffold can only be dismantled after the unit's project leader
confirms and signs a dismantling permit.
7.5.9 When the operation scaffold is dismantled, a safe area shall be marked out.
Warning signs shall be set up. Special personnel shall be assigned to monitor it.
7.5.10 Before dismantling, the scaffold shall be cleaned of utensils, excess materials
and debris.
8 Inspection and acceptance
8.0.1 The inspection and acceptance of scaffold structural accessories entering the
construction site shall comply with the following regulations.
8.0.3 The inspection and acceptance of the shoring scaffold shall meet the following
requirements.
8.0.4 When one of the following situations occurs, the operation scaffold shall be
inspected and accepted.
8.0.5 The inspection and acceptance of operation scaffolds shall meet the following
requirements.
9 Safety management and maintenance
9.0.1 Scaffold erection workers shall wear safety helmets, safety belts and non-slip shoes correctly.
9.0.2 The requirements of the construction plan shall be implemented and the scaffold
installation and removal process shall be followed.
9.0.3 The use of scaffold shall be managed by designated personnel.
9.0.4 The construction load on the working layer shall be controlled and shall not
exceed the design value.
9.0.5 If preloading is required, the load distribution shall be consistent with the design
plan.
9.0.6 During the loading process of scaffold, it shall be carried out according to the
principles of symmetry, layering and grading. There shall be no centralized loading and
unloading. Special personnel shall be assigned to monitor the working status of the
scaffold in the safe area.
9.0.11 Obvious warning signs and anti-overrun railings shall be installed at the door
openings and passing passages of the frame.
9.0.12 The scaffold work area shall be neat and sanitary. Materials shall be stacked
neatly and orderly. Channels shall be clear.
9.0.13 When encountering major sudden weather changes, preventive measures shall
be taken in advance.
...... Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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