|
US$369.00 · In stock
Delivery: <= 4 days. True-PDF full-copy in English will be manually translated and delivered via email.
LY/T 3141-2024: (Testing methods for wooden components of cultural relics buildings)
Status: Valid LY/T 3141: Evolution and historical versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Standard Title (Description) | Status | PDF |
| LY/T 3141-2024 | English | 369 |
Add to Cart
|
4 days [Need to translate]
|
(Testing methods for wooden components of cultural relics buildings)
| Valid |
LY/T 3141-2024
|
| LY/T 3141-2019 | English | 559 |
Add to Cart
|
3 days [Need to translate]
|
Technical code on appraisal rating for wooden member of ancient timber building
| Obsolete |
LY/T 3141-2019
|
Basic data | Standard ID | LY/T 3141-2024 (LY/T3141-2024) | | Description (Translated English) | (Testing methods for wooden components of cultural relics buildings) | | Sector / Industry | Forestry Industry Standard (Recommended) | | Word Count Estimation | 16,132 | | Date of Issue | 2024-02-07 | | Date of Implementation | 2024-06-01 | | Issuing agency(ies) | State Forestry and Grassland Administration | LY/T 3141-2019: Technical code on appraisal rating for wooden member of ancient timber building---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
(Technical specification for safety appraisal of ancient building wooden members)
ICS 91.080.20
P 23
LY
People's Republic of China Forestry Industry Standard
Technical code for safety appraisal of ancient building wooden members
Technical code on appraisal rating for wooden member of ancient timber building
2019-10-23 released
2020-04-01 implementation
Published by the National Forestry and Grassland Administration
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
Please note that some elements of this document may involve patents. The issuer of this document is not responsible for identifying these patents.
This standard was proposed and managed by the National Timber Standardization Technical Committee Structural Timber Subcommittee (SAC/TC41/SC4).
This standard was drafted. Institute of Wood Industry, Chinese Academy of Forestry, Shanxi Province Ancient Building Maintenance Quality Supervision Station, Chinese Culture
Heritage Research Institute, Beijing Jiaotong University, Beijing Institute of Ancient Architecture, Beijing Institute of Construction Engineering Co., Ltd., Ministry of Science and Technology
Torch High-tech Industrial Development Center, Guangdong Runcheng Chuangzhan Wood Industry Co., Ltd.
The main drafters of this standard. Zhou Haibin, Wang Weibin, Yong Xinqun, Yang Na, Zhang Tao, Song Huijie, Chen Yongping, Zhong Yong, Wang Shuangyong, Wu
Guofang, Lou Wanli, Guan Runkai.
Technical code for safety appraisal of ancient building wooden members
1 Scope
This standard specifies the terms and definitions, basic provisions, damage survey items and bearing capacity verification items of the safety assessment of wooden components of ancient buildings.
Purpose To identify ratings.
This standard applies to the safety inspection and appraisal of the wooden members of the following buildings.
a) Wooden structures and ancient buildings approved by various levels of government as cultural relics protection units;
b) Wood that has not yet been approved for publication as a cultural relics protection unit, but has been registered and announced as a non-removable cultural relic by the district and county government cultural relics administration
Structure ancient building
c) wooden structure ancient buildings that have not been classified as immovable cultural relics but have been announced as historical buildings by governments at all levels;
d) An ancient wooden structure that has not yet been identified as a historical building, but does have conservation value.
2 Normative references
The following documents are essential for the application of this document. For dated references, only the dated version applies to this document.
For undated references, the latest version (including all amendments) applies to this document.
GB/T 28990 Nondestructive testing procedures for internal decay and elastic modulus stress wave of ancient building wooden components
GB 50005 wood structure design standard
GB 50009 Load Code for Building Structures
GB 50165 Technical Specifications for Maintenance and Reinforcement of Timber Structures of Ancient Buildings
GB 50292 Civil Building Reliability Evaluation Standard
LY/T 2146 Non-destructive detection method and decay classification of wooden components of ancient buildings
3 terms and definitions
The terms and definitions defined in GB 50165 and the following apply to this document.
3.1
Ancient timber building
Buildings with wooden components as the main vertical load-bearing components are valuable buildings for the study of social, political, economic, and cultural heritage.
3.2
Wood unit
Single or combined element in the wooden frame of an ancient building.
3.3
Dominant member
Its failure will lead to the failure of related components and endanger the structural system safety.
3.4
Common member
Its failure will not lead to the failure of the main components, and does not endanger the structural system safety.
4 Basic requirements
4.1 Identification object
The safety appraisal of wooden elements of ancient buildings should be carried out in the following cases.
1) Major wooden components in key maintenance projects;
2) Wooden members monitored regularly;
3) wood elements that change their use or conditions of use;
4) Wooden members found to have safety problems during use;
5) Wooden members affected by major disasters such as earthquakes, wind, floods, fires, and lightning;
6) Wooden members with special requirements.
4.2 Identification procedure
4.2.1 The safety appraisal of wooden components of ancient buildings shall be carried out according to the following procedures.
1) Accept the commission. According to the requirements of the client, determine the purpose, content and scope of the safety evaluation of the wooden members.
2) Preliminary investigation. collect and analyze the original data of ancient buildings, including drawings, building history, past repair data, and conduct
Field investigation.
3) Inspection and verification. On-site inspection of the state of ancient building wood components, including. component measurement, deformation measurement, damage inspection, tree species
Appraisal, material performance testing, etc., if necessary, instrument testing and structural check calculations.
4) Level determination. conduct a comprehensive analysis of the data of surveys, inspections and calculations, and integrate their safety levels.
5) Disposal suggestions. Put forward principled disposal suggestions for the identified ancient building wood elements.
6) Issue a report.
4.3 Identification requirements
4.3.1 There are two levels of safety appraisal for wooden elements of ancient buildings. The classification and rating standards of each level are shown in Table 1.
Table 1 Levels, grades, and standards of safety evaluation of wood members
Hierarchical identification object rating standard
A survey item a 'has no damaged points, or the original damaged points have been repaired
b 'Only minor or suspected damage was found, but it did not affect safety
c 'has a moderate damage point, which has affected the safety of the project
d 'has severe damage points, which will endanger the safety of the project
The safety of a single component a meets the requirements of class a of this standard and has sufficient bearing capacity
b The safety is slightly lower than the requirements of level a of this standard, and it has not significantly affected the carrying capacity.
c The safety does not meet the requirements of level a of this standard, which significantly affects the carrying capacity
d. Safety does not meet the requirements of Class a of this standard, which has seriously affected the carrying capacity.
4.3.2 When the safety of a wooden member is evaluated according to the rating results of the damage survey item, the damage level of the member shall be determined according to Table 2.
Table 2 Evaluation criteria for damage rating of load-bearing components
Grade standard
a component should be a 'grade in the survey project; or no c' grade and d 'grade, only individually b' grade
There should be no c 'and d' grades in the survey items of b components, and b 'grade is more than a'
c The lowest level of the component survey item is c 'level
The lowest level of the d component survey project should be d 'level; or no d' level, but c 'level is more than 50%
4.3.3 When the safety of load-bearing wood components and their connections is determined according to the carrying capacity, the level of each check item shall be determined separately as specified in Table 3.
Level, and take the lowest level as the safety level of the bearing capacity of the component.
Table 3 Rating of load-bearing components and their connection safety levels according to bearing capacity
Component category
R/γ0S
Class a Class b Class c Class d
Main components and connections ≥1.0 ≥0.95 ≥0.90 < 0.90
General components ≥ 1.0 ≥ 0.90 ≥ 0.85 < 0.85
Note. R and S in the table are the resistance and action effects of structural members, respectively, determined according to GB 50009 and GB 50292; γ0 is the coefficient of structural importance, and World Cultural Heritage
Land and buildings of national key cultural relics protection units are taken as 1.1, and other buildings are taken as 1.0.
4.3.4 According to the damage survey item and bearing capacity check item, assess the damage level and bearing capacity level of the wooden members respectively, and take the comparison
The lower level serves as the final safety level of the wooden members.
4.3.5 The safety level of wooden members shall be used as the basis for judging the maintenance and reinforcement of the members. See Table 4 for processing requirements of different grades of components.
Table 4 Treatment requirements for wood components based on safety levels
Security level processing requirements
a No action necessary
b No action required
c can take action
d must take immediate action
5 Appraisal and rating of the damage survey project
5.1 The damaged points of the wooden building survey project of ancient buildings shall be divided into a 'grade, b' grade, and c 'according to their degree of influence on the structure and component safety.
Level and d 'level. The a 'and b' levels can be judged by the appraiser based on the actual condition, and the c 'and d' levels should be judged by the appraiser.
Determine the actual severity.
5.2 The damaged points of load-bearing wooden columns of ancient buildings shall be determined according to Table 5.
Table 5 Evaluation criteria for bearing wood column damage
Survey item survey content c 'level or d' level
Material situation
Natural defect
Characteristic size of any defect in key stress areas, knots, oblique grains or shrinkage cracks
Exceeds the limits in Table 6 with other damage
decay
When only the surface is decayed and deteriorated, ρ > 1/5 or the remaining cross section is not acceptable
When there is only heart rot, ρ ＞ 1/7 or unqualified according to the remaining section
Coexisting heart rot, surface decay, and aging
Insects bore holes; or no holes were found, knocking empty drum sounds
3 Column damage cracks show signs of fracture, splitting or crumpling within the range of the column length
4 Lateral bending sagittal height δ δ ＞ L0/250
Pedestal and pedestal
Resistance
The actual bearing area between the bottom surface and the column foundation and
Ratio of the original cross-sectional area of the column at the leg
Less than 3/5
Eccentric check
If the column is an eccentric compression member, the deviation of the center of the actual bearing surface from the column axis should be determined.
The eccentricity and its effect on the original eccentricity were unqualified according to the eccentricity check.
6 Pillar misalignment
Displacement between column and column base and column diameter (or
Column cross section) the ratio of dimensions along the dislocation direction
More than 1/6
Previous reinforcement
The original pier joint is in good condition with new deformation or displacement of the column body, or the tenon-and-mortise joint has been degummed, cracked, or the hoop has been loosened
Original grouting effect
The original grouting slurry has poor adhesion to wood, the slurry shrinks, and there are empty drum sounds when struck; columns
Obvious wrinkling or deformation
The intactness of the original excavation site has become loose, degummed, or new decay has occurred
Note. ρ is the ratio of the area occupied by decay and aging deterioration (total) to the entire cross-sectional area on any section; L0 is the unsupported length of the column.
Table 6 Evaluation criteria for natural defects
Item natural defect
Log Member Square Member
Bending member or bending
member
Compressed member or secondary
Bending member
Bending member or pressure
Curved member
Compressed member or secondary
Bending member
1 knot
On either side of the component (or along the perimeter
Length) Any 150mm length
The sum of the sizes of the knots should not
Larger than the width of the face
Log perimeter)
2/5 2/3 1/3 2/5
The maximum size of each knot should be
Not more than the log circumference of the measured part
long
1/5 1/4--
Twill
Average tilt over any 1m length
Inclined height should not be greater than
80mm 120mm 50mm 80mm
Shrink
crack
Not allowed on the sheared surface of the joint
Attach the sheared surface of the joint
Near, its crack depth (the opposite
Use the sum of the two when cracking) should not
more than the
1/4 in diameter 1/2 in width 1/4 in width
Annual ring
width
Should not be greater than 4mm 4mm 4mm 4mm
5.3 The damaged points of load-bearing wooden beams and concrete of ancient buildings shall be determined according to Table 7.
Table 7 Evaluation criteria for bearing wood beam and concrete damage
Item survey item survey content c 'level or d' level
1 Material defects
decay
When only the surface is decayed and deteriorated, the beam ρ > 1/8 or the remaining section is not qualified.
When the end part (within the support range) has surface decay and aging deterioration, regardless of the size of ρ, it is regarded as a point of damage.
The existence of heart rot, regardless of the size of ρ, is regarded as the point of damage
Insects bore holes; or no holes were found, knocking empty drum sounds
Natural defect
At critical stress locations, any defects such as knots, oblique textures, or shrinkage cracks exceed the limits in Table 6, and
Have other damage
2 Bending deformation
Maximum vertical deflection
ω1 or ω1 '
When h/L ＞ 1/14, ω1 ＞ L2/2100h
When h/L≤1/14, ω1 ＞ L/150
For beams and rafters over 300 years, if there is no other damage, it can be judged as ω1 '＞ ω1 h/50
Lateral bending sagittal height ω2 ω2 ＞ L /.200
3 Damaged beam
There are cracks or cracks across the interruption lines, but there are signs of crumple on the upper surface of the beam
Beam end split (not included
Shrinkage crack)
End cracks or oblique cracks caused by stress or excessive deflection
Non-original sawn, open
Slot or drill
Failed inspection based on remaining section
Previous reinforcement
Beam end original splicing reinforcement
Intact
The original splicing has been deformed, or has been degummed, or the bolts have been loosened
The original grouting effect The original grouting body shrinks, there is empty drum sound on percussion, or the deflection of the beam increases
Note. ρ is the ratio of the area occupied by decay and aging deterioration (total of both) to the entire cross-sectional area on any section; L is the calculated span; h is the height of the member section.
5.4 The bucket has the following damage and should be regarded as the point of damage.
a) Obvious deformation, misalignment or twisting of the bucket;
b) the relative deflection of the bending member in the bucket has exceeded 1/120;
c) The forsythia is broken, the small bucket falls off, and two consecutive occurrences occur under each one;
d) The twist of 栱 is more than 3mm, or the depression of the bucket is more than 3mm;
e) Decaying, worm-eaten or aging deterioration of the wood of the bucket bucket has affected the bucket bucket force;
f) There are obvious signs of damage at the stigma or corner.
5.5 The damaged points of roof wooden members shall be determined according to Table 8.
Table 8 Evaluation criteria for damage to roof members
Item survey item survey content c 'level or d' level
1 purlin
The material has become decayed or moth-eaten, or is heavily wet
The deflection is greater than 1/100 of the span and has caused significant roof deformation
The connection between 椽 and 檩 is not nailed, or the nail is rusted
2 Purlin
Material is evaluated according to Table 7
Mid-span maximum deflection ω1
When L≤3m, ω1 ＞ L/100
When L ＞ 3m, ω1 ＞ L/120
Most purlins have large deflections that cause rain. Regardless of the size of ω1, they are regarded as
Break point
Purlin support length a
Supported on wooden members, a < 60mm
Supported on masonry, a < 120mm
Tendon at the end of the purlin under stress, or the purlin rolls outside, or there is no anchor between the purlin and the beam
Melon pillar, horned llama
Material is decaying or moth-eaten
Slope, mortise, or split in good construction
Wing angle, corner beam,
Yu
Material is decaying or moth-eaten
No reliable tie at the fixed position at the rear of the angle beam
The damage process of the tail beam of the angle beam and the end of the beam
Split or broken
The wing corners and eaves are obviously drooping
Note. L is the calculated span of purlin.
5.6 The damage points of wooden members on the floor shall be determined according to Table 9.
Table 9 Evaluation criteria for floor component damage
Item survey item survey content c 'level or d' level
1 Floor corrugated (joist)
Material is evaluated according to Table 7
Maximum vertical deflection ω1 ω1 > L/180, or severe somatosensory tremor
Lateral bending sagittal height ω2
(Raw joists are not checked)
ω2 ＞ L /.200
End tenon-and-mortise condition without reliable anchoring and support length less than 60mm
2 The condition of floor wood decay and surface damage can no longer strengthen the horizontal rigidity of the floor
Note. L is the calculated span for joists.
6 Appraisal and rating of carrying capacity check items
6.1 When checking the bearing capacity of structures or components, the following requirements should be observed.
a) The structural analysis method used for checking the structural members should refer to the provisions of the current national design code;
b) The calculation model used for checking the structural members should be consistent with its actual stress and structural conditions;
c) Structural loads shall be implemented in accordance with the provisions of GB 50165;
d) the strength grade of wood shall be determined in accordance with Appendix A;
e) The geometric parameters of the structure or component shall be measured on site, and the effective cross-sectional area of wooden members with material defects shall be determined in accordance with Appendix B.
6.2 Beam and column members shall be checked for bearing capacity in accordance with the relevant provisions of GB 50005 and shall comply with the following provisions.
a) When the beam is excessively bent, the effective span of the beam should be determined according to the actual contact between the support and the beam, and the eccentricity of the support force transmission should be considered.
The support member is affected by force;
b) Columns shall be calculated according to the hinges at both ends. The length shall be taken as the distance between the lateral supports. Columns with a change in cross-sectional dimensions may be measured according to the intermediate section rule.
Inch check
c) If the original component has been partially damaged or decayed, it shall be checked against the remaining effective section.
6.3 When checking the wooden structure of ancient buildings, the timber design strength and elastic modulus should meet the following requirements.
a) It shall be implemented in accordance with the provisions of GB 50005 and multiplied by the coefficient of structural importance 0.9; there are special requirements to be determined separately.
b) For components whose appearance has been significantly deformed or whose wood is aging, they shall also be multiplied by the adjustment factors specified in Table 10.
c) For components that are calculated only under dead load, they should also be multiplied by the adjustment factor specified in GB 50005.
Table 10 Adjustment factors considering long-term load and wood aging
Building construction time
Between (year)
Adjustment coefficient
Compressive design strength of the grain along the line Bending and shear design strength along the grain
100 0.95 0.9 0.9
300 0.85 0.8 0.85
> 500 0.75 0.7 0.75
Note. When the number of years in the table is between the listed values, the value of the adjustment coefficient can be determined by linear interpolation.
Appendix A
(Informative appendix)
Determination of wood strength grade
A.1 The strength level of wood can be determined according to the following steps.
a) To identify the tree species of wood used for wood components, determine the intensity level according to the correspondence table of timber tree species and intensity levels in GB 50005.
b) Determine the elastic modulus of the wooden members according to the GB/T 28990 non-destructive testing method for longitudinal stress waves, and then derive other mechanical indicators,
Comprehensively determine its intensity level. If the length of wooden members is less than 1m, non-destructive testing of stress waves can be omitted.
c) Take the lowest level above as the strength grade of the timber used in this component.
A.2 The tree species identification and sampling of wood used for wooden members shall avoid new mechanical damage to the wooden members, and the sampling size shall be
Keep it as small as possible.
A.3 Nondestructive testing of stress wave
A.3.1 Arrange the probe points along the grain direction of the wooden member. The two probes are embedded at an angle of 45 ° to the surface of the wooden member.
On the plane.
A.3.2 If there is a ground rod layer on the surface of the wooden member, the probe should be embedded below the ground rod layer.
A.3.3 The distance between the measuring points of the two probes shall not be less than 1m.
A.3.4 Every wooden member should be tested at least 2 locations along the whole body, and there should be no c 'or d' grade material defects between the probes in each area.
A.3.5 Determine the elastic modulus of the wooden member by calculating the propagation velocity of the stress wave, and take the lowest elastic modulus value as the elasticity of the member
Modulus.
A.3.6 The average density ρmean (g/cm3) of the wood used to determine the elastic modulus of the stress wave can be measured by an impedance meter (recommended model RESISTOGRAPH
4453-S) The measured impedance value is calculated and determined. The impedance meter should be driven at the non-damaged part of the wooden member, perpendicular to the wooden member, and the impedance value should be
Take the average of the entire detection path. Reference relationship. pine, ρmean = 0.0066 * RM-0.23; poplar, ρmean = 0.0061 * RM-0.27.
A.3.6 Other mechanical design indicators are determined with reference to the following formulas.
Fm = (MOE-4500)/300
Ft = 0.64 (Fm)
Fc, 0 = 2.1 (Fm) -5.6 × 10-2 (Fm) 2 5.6 × 10-4 (Fm) 3
Fv = 0.24 (Fm) -5.2 × 10-5 (Fm) 2 5.0 × 10-3 (Fm) 3
Fc, 90 = 25.5 (ρmean) -5.61
Where. MOE, modulus of elasticity, MPa; Ft, flexural strength, MPa; Fc, 0, compressive strength along the grain, MPa; Fv, shear strength along the grain
MPa ;; Fc, 90, transverse compressive strength, MPa.
Appendix B
(Informative appendix)
Non-destructive testing of wood component material defects
B.1 Defect detection of wood members should be carried out as follows.
a) First, use a small hammer to strike the surface of the wooden member to determine whether there are suspected defects in the wooden member, and make a preliminary judgment of the approximate
position;
b) If external defects are suspected, use Pilodyn probe method to confirm the suspected defects; if internal defects are suspected, use ultrasonic or
Libo conducts cross-section inspection of wooden members to confirm suspected defects;
c) After confirming the specific location of the defect, use an impedance meter to determine the boundary of the defect.
B.2 External suspected defect detection
B.2.1 At the suspected defect site, use the Pilodyn probe method in LY/T 2146 to detect that the increase rate of the penetration depth of the probe is not zero.
Determined as a material defect peripheral area.
B.2.2 After confirming the defect, the maximum depth of the defect shall be detected with an impedance meter. The area where the resistance value reduction rate is not zero can be judged as a defect
Deep into the area.
B.3 Internal suspected defect detection
B.3.1 Square timber members
B.3.1.1 In the vicinity of the suspected defect site, select different sections for ultrasonic inspection in order, and the interval between each section should be between 50-100mm.
Inside.
B.3.1.2 For each section, measure points are arranged on four sides of the wooden member. The measurement points are symmetrically distributed up and down, and the measurement points on the same side are equally spaced.
The distance is not more than 50mm. Virtual meshing of the cross section of the w...
|