CN105987846A - Method for determining fatigue resistance of all-welded truss bridge - Google Patents
Method for determining fatigue resistance of all-welded truss bridge Download PDFInfo
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- CN105987846A CN105987846A CN201510052428.5A CN201510052428A CN105987846A CN 105987846 A CN105987846 A CN 105987846A CN 201510052428 A CN201510052428 A CN 201510052428A CN 105987846 A CN105987846 A CN 105987846A
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Abstract
The invention belongs to the field of fatigue analysis of a welded steel structure bridge, and especially relates to a method for determining fatigue resistance of an all-welded truss bridge. The method comprises the following steps: determining a fatigue curve of researched fatigue detail by employing a theoretical method, examining the fatigue curve by an experiment method, correcting the fatigue curve at the fatigue detail, and finally arranging to obtain the fatigue resistance at the fatigue detail. The combination of the determining method and the effect analysis of the fatigue load effect can be used for anti-fatigue design and fatigue life evaluation of the all-welded truss bridge. A technical scheme of the invention is characterized in that compared with the pure theoretical method, the precision of the analysis result in the invention is high, compared with a pure testing method, the investment of a whole work process is less, so that the method is the fatigue resistance assessment method which has the advantages of accuracy and economy.
Description
Technical field
The invention belongs to the analysis of fatigue field of welded steel structure bridge, particularly relate to a kind of determine full weldering truss-type bridges fatigue resistance
Method.
Background technology
Steel bridge owing to it is lightweight, span ability is big, convenient processing and manufacture, have benefited from after reform and opening-up steel yield and matter with
And the lifting of processing and manufacturing skill, China has built plurality of highway, ferrum steel bridge.But, hide behind in Large scale construction
The disadvantage, what performance at present was the most prominent is the fatigue crack of steel bridge welding node, and the appearance spreading fracture of fatigue crack may
Cause the bearing capacity even structure that transfinites thoroughly to be destroyed, because this destruction is the most paroxysmal, easily cause a serious accident and personnel
Damage.
The fatigue process of material is extremely complex, understands that it is formed the most completely.The fatigue strength of component refers generally to material
Material is resisted applied cyclic load effect and is not cracked the ability of (or flawless extension), and with the load (one that can bear
As for stress amplitude Δ σ) size and corresponding cycle-index N represent.A kind of common methods of the fatigue strength of evaluation structure component
It is that the S-N curve provided according to specification determines stress amplitude Δ σ corresponding to design fatigue life.Due to different joint forms (commonly referred to as
For tired details) fatigue life be different, even if specification providing the most eurypalynous S-N curve still can not contain institute
The tired details having.
Owing to fatigue rupture is very sensitive to the local detail stress of component, therefore scholars propose tired partial analysis method.Tired
Labor partial analysis method refers generally to the strength assessment based on local stress or strain parameter, and it considers the local damage mistake of fatigue of materials
Journey (i.e. circulates crack initiation, circulation cracks can spread and final fracture).The tired jagged stress method of partial analysis method, breach should
Political reform, cracks can spread method, notch stress intensity factor method etc..Wherein local stress approach considers the stress of welding toe, for every class
Weld seam all has the S-N curve of correspondence." notch stress method " or " breach Strain Method " is then directed to the maximum in breach should
Power is analyzed, only one S-N curve.But use above method carry out analysis of fatigue need first to determine local stress or
Notch stress.Methods of mechanics the most commonly used in Structural Design cannot meet calculating local stress or breach should
The needs of power, and precision higher entity finite element method can not be fully achieved the required precision required for design or assessment.
Summary of the invention
The present invention provides a kind of and determines the full method welding truss-type bridges fatigue resistance, cannot expire with solve to propose in above-mentioned background technology
Foot analyzes the problem needed.
Technical problem solved by the invention realizes by the following technical solutions: the present invention provide one to determine full weldering truss-type bridges is tired
The method of labor drag, it is characterised in that: comprise the following steps:
The first step, sets up steel girder bridge beam element model, determines that welding to be analyzed connects by fatigue load given in load rule
Internal force at Tou；
Second step, uses body unit to set up the spatial entities FEM (finite element) model of solder joint fatigue joint to be analyzed, by beam element mould before
Load at the actual loading situation butt joint that type calculates；
3rd step, according to the requirement of actual design drawing, processes a prototype comprising joint to be analyzed, joint material,
Welding manner, solder flux etc. should be consistent completely with design；
4th step, uses loseless method to measure the surface residual stress of joint welding to be analyzed on prototype, uses lossless simultaneously
Detection method measures the constructional deficiency on prototype near weld seam to be analyzed, and both the above testing result is real in view of finite element
In body Model；
5th step, the internal force using the first step to calculate applies static load as load to prototype, measures weld defect simultaneously
The stress actual stress at place, if detection does not finds defect, then measures the stress in whole fusion length, and finds out maximum, will
The stress recorded stress counted with solid finite meta-model compares, and is modified solid finite meta-model；
6th step, the stress that photoelastic test records, divided by by the mechanics of materials counted commissure stress, is at this welding details
Notch stress-concentration coefficient；In solid finite meta-model along weld seam to be analyzed change constructional deficiency position, can calculate one
The notch stress-concentration coefficient of series, remembers that maximum therein is K.It is calculated as follows the tired bent of weld fatigue details to be analyzed
Line:
NKmΔσm=C
In formula: N is fatigue life；K is the notch stress-concentration coefficient obtained by actual measurement and finite element analysis；M and C is
The notch stress fatigue curve parameter provided in specification, C=2.278E13, m=3.
7th step, carries out fatigue test to full-scale specimen, obtains (Δ σ, a N) data point, if this data point is positioned at
Above six step formula curves, then the 6th step formula is required truss-type bridges weld detail fatigue resistance.If this data point is positioned at
Below 6th step formula, then needing to move at data point the 6th step formula on double logarithmic chart, revised 6th step is public
Formula is required truss-type bridges weld detail fatigue resistance.
The invention have the benefit that
Can be used for entirely welding by this detection method is combined with Fatigue Load effect analysis truss-type bridges Anti fatigue Design and
Fatigue Life.It is advantageous that of the technical program: relatively pure theoretical method, the precision of analysis result is high, and relatively pure
The small investment of the most whole work process of test method, is a kind of fatigue resistance appraisal procedure taking into account accuracy and economy.
Detailed description of the invention
The inventive method principle: utilize finite element modelling to obtain intending the preliminary data of fatigue analysis details, then use full scale model test
Result of calculation is modified improving the precision of analysis result.The step of the present invention is as follows: determines initially with theoretical method and is ground
Study carefully the fatigue curve of tired details, then by experimental technique, fatigue curve is tested, and to the fatigue curve at tired details
It is modified, finally arranges the fatigue resistance obtained at tired details.
Technical solution of the present invention is characterized as:
A kind of method determining full weldering truss-type bridges fatigue resistance, taking full advantage of all weld details has in its weld seam local indentation, there
And the feature of an only fatigue curve, as long as the corresponding relation established between indentation, there focus stress and far field nominal stress (lacks
The factor of stress concentration at Kou), it is possible to it is derived by based on far field stress saving corresponding to this truss welding by indentation, there fatigue curve
The fatigue curve of point.Due to existing FEM calculation precision and computational methods and material tests ability and the limitation of precision, use
The result of calculation of Finite Element Method is carried out supplementary perfect from the following aspects by full scale test method, thus improves computational accuracy:
1 replaces physical dimension imaginary in FEM (finite element) model and defect shape with physical dimension and the defect shape of full-scale specimen actual measurement；
2 replace fabricating the residual stress distribution assumed by actual measurement residual stress distribution；
3 check, with the notch stress-concentration coefficient of actual measurement, the notch stress-concentration coefficient that FEM calculation obtains；
4 check according to the counted Fatigue Life Curve of theoretical derivation with actual measurement Predict Fatigue Life of Components.
Full-scale specimen used in this method by the processing mode manufacture of actual bridge, process of the test needs use ultrasonic phase array instrument,
FEM (finite element) model can use common commercial finite element software, further explains the detailed description of the invention of this detection method below
State:
(1) foundation of steel girder bridge beam element model
Use beam element simulation truss member that full weldering truss-type bridges is carried out FEM (finite element) model modeling: each beam element cross section geometric parameter is pressed
Design section determines, consolidation process is pressed in beam element constraint at node, and the constraint between truss and bridge pier is pressed practical situation and processed,
Truss-type bridges fatigue load is loaded by specification, and calculates and the rod end internal force paying close attention to each truss element that full weldering node is connected.
(2) solid finite meta-model is set up
Use solid element (solid element that can simulate elastic force balance is more, but is advisable with 20 node isoparametric elements) according to being analyzed
The actual drawing structural modeling of node.Each bar that is connected this node does following constraint and processes: to farthest from being paid close attention to tired details
Rod member at rod end by fully consolidated for 6 direction degree of freedom of node each on cross section, to other rod members in end by first step beam element mould
The rod end internal force that type obtains loads in the distribution of each node.The density of in modeling it is ensured that analyzed commissure grid, due to needs mould
Intend notch stress-concentration, so at least should be by 5 layer unit on throat depth direction.
(3) processing prototype test specimen
Process the prototype test specimen 1 of paid close attention to node.The material of test specimen, specification, welding manner, position while welding and execute
Relevant treatment work (as postwelding is polished) etc. in work should require with construction technology and design to be consistent.But specimen Design allows to examine
The far-end of each rod member being connected with analysis node is widened thickening process so that installing and connecting by the impact considering loading equipemtn etc.
Connect.The later stage it is considered as time model is carried out static loading and fatigue loading between jack or tired actuator and test specimen when design
Connected mode optimization design.
(4) Non-Destructive Testing and static test
Respectively the weld seam paid close attention in prototype is carried out the detection of following items:
A) surface residual stress detection (being proposed with x-ray diffraction method)；
B) weld shape detection (suggestion visual inspection coordinates vernier caliper measurement)；
C) weld defect detection (suggestion ultrasonic phase array scanning)
According to (1st) step beam type model counted load, prototype is loaded, and the actual stress value measuring weld seam indentation, there (is built
View uses photoelastic test to measure).With the surface soldered residual stress of actual measurement, weld shape, weld defect to entity finite element mould
Type is modified, and calculates the maximum tension stress of paid close attention to weld seam indentation, there by revised model, by result of calculation and actual measurement knot
Fruit compares, if two result differences more than 10%, then needs the reason considering to cause a deviation, and enters FEM (finite element) model
Row is revised.
(5) derivation fatigue resistance curve
Being modified specification fatigue curve according to actual measurement stress raisers coefficient, correction formula is as follows:
NKmΔσm=C (1)
In formula: N is fatigue life；K is the notch stress-concentration coefficient obtained by actual measurement and finite element analysis；M and C is specification
The notch stress fatigue curve parameter of middle offer, C=2.278E13, m=3.
(6) fatigue test revise fatigue resistance curve
Full size fatigue sample is carried out fatigue sample, until detection finds that fatigue crack occurs in the tired details paid close attention to.Tired examination
Test applied load it is ensured that total is in elastic state, and fatigue test puts on each rod end of full-scale specimen
Fatigue load distribution should distribute in strict accordance with counted fatigue load in beam element model in (1st) portion.When record test stops
The fatigue life of full-scale specimen, and be together drawn on respectively with fatigue life and stress amplitude as coordinate axes with the curve in formula (1)
Double logarithmic chart in, if fatigue life point be positioned at below curve, then need curvilinear translation to coordinate points position, again
This fatigue curve is revised, if coordinate points corresponding to fatigue life is on curve, then need not fatigue curve is carried out
Revision.
Utilize technical solutions according to the invention, or those skilled in the art is under the inspiration of technical solution of the present invention, designs
Similar technical scheme, and reach above-mentioned technique effect, all fall into protection scope of the present invention.
Claims (4)
1. one kind determines the full method welding truss-type bridges fatigue resistance, it is characterised in that: comprise the following steps:
The first step, sets up steel girder bridge beam element model, determines that welding to be analyzed connects by fatigue load given in load rule
Internal force at Tou；
Second step, uses body unit to set up the spatial entities FEM (finite element) model of solder joint fatigue joint to be analyzed, by beam element mould before
Load at the actual loading situation butt joint that type calculates；
3rd step, according to the requirement of actual design drawing, processes a prototype comprising joint to be analyzed, joint material,
Welding manner, solder flux etc. should be consistent completely with design；
4th step, uses loseless method to measure the surface residual stress of joint welding to be analyzed on prototype, uses lossless simultaneously
Detection method measures the constructional deficiency on prototype near weld seam to be analyzed, and both the above testing result is real in view of finite element
In body Model；
5th step, the internal force using the first step to calculate applies static load as load to prototype, measures weld defect simultaneously
The stress actual stress at place, if detection does not finds defect, then measures the stress in whole fusion length, and finds out maximum, will
The stress recorded stress counted with solid finite meta-model compares, and is modified solid finite meta-model；
6th step, the stress that photoelastic test records, divided by by the mechanics of materials counted commissure stress, is at this welding details
Notch stress-concentration coefficient；In solid finite meta-model along weld seam to be analyzed change constructional deficiency position, can calculate one
The notch stress-concentration coefficient of series, remembers that maximum therein is K.It is calculated as follows the tired bent of weld fatigue details to be analyzed
Line: NKm△σm=C；
7th step, carries out fatigue test to full-scale specimen, obtains (△ σ, a N) data point, if this data point is positioned at
Above six step formula curves, then the 6th step formula is required truss-type bridges weld detail fatigue resistance.If this data point is positioned at
Below 6th step formula, then needing to move at data point the 6th step formula on double logarithmic chart, revised 6th step is public
Formula is required truss-type bridges weld detail fatigue resistance.
A kind of method determining full weldering truss-type bridges fatigue resistance the most according to claim 1, it is characterised in that: N is fatigue life；
K is the notch stress-concentration coefficient obtained by actual measurement and finite element analysis；M and C is bent for the notch stress fatigue provided in specification
Line parameter, C=2.278E13, m=3.
A kind of method determining full weldering truss-type bridges fatigue resistance the most according to claim 1, it is characterised in that: described loseless method
For x-ray diffraction method.
A kind of method determining full weldering truss-type bridges fatigue resistance the most according to claim 1, it is characterised in that: described Non-Destructive Testing
Method is the ultrasound phase-control tactical deployment of troops.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109883859A (en) * | 2019-02-14 | 2019-06-14 | 上海交通大学 | Subregion strain testing method in heterogene structure's welding point During Low Cycle Fatigue |
| CN110263401A (en) * | 2019-06-12 | 2019-09-20 | 南京毕慕智能建筑科技有限公司 | Steel box-girder top plate-longitudinal rib welding details residual stress relaxation effect appraisal procedure |
| CN112268799A (en) * | 2020-10-16 | 2021-01-26 | 中国直升机设计研究所 | Static strength and fatigue strength integrated test verification method for composite material structure |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109883859A (en) * | 2019-02-14 | 2019-06-14 | 上海交通大学 | Subregion strain testing method in heterogene structure's welding point During Low Cycle Fatigue |
| CN110263401A (en) * | 2019-06-12 | 2019-09-20 | 南京毕慕智能建筑科技有限公司 | Steel box-girder top plate-longitudinal rib welding details residual stress relaxation effect appraisal procedure |
| CN112268799A (en) * | 2020-10-16 | 2021-01-26 | 中国直升机设计研究所 | Static strength and fatigue strength integrated test verification method for composite material structure |
| CN112268799B (en) * | 2020-10-16 | 2022-09-09 | 中国直升机设计研究所 | Static strength and fatigue strength integrated test verification method for composite material structure |
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Application publication date: 20161005 |