CN109885973B - Deformation cycle damage calculation method - Google Patents
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- CN109885973B CN109885973B CN201910221689.3A CN201910221689A CN109885973B CN 109885973 B CN109885973 B CN 109885973B CN 201910221689 A CN201910221689 A CN 201910221689A CN 109885973 B CN109885973 B CN 109885973B
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Abstract
The invention discloses a deformation cycle damage calculation method, which comprises the following steps: establishing a first load displacement curveA bar skeleton curve and a second skeleton curve; determining the intact slope k of a skeleton curve 1 Peak load of skeleton curve P m The point of failure of the test piece; determining characteristic load P under each stage of displacement control Ei 、P Ri 、P Ci And P △i (ii) a Determining a damage value D according to a damage calculation formula di 、D Ci And D Ri . According to the invention, a load displacement curve obtained by test loading is utilized, the bearing capacity is taken as a basic factor for evaluating the damage condition, the initial loading point is taken as a damage starting point or a self-defined damage starting point, and the influence of cyclic loading on the damage of a test piece under the same displacement is considered, so that a new method and a new thought are provided for structural earthquake damage research.
Description
Technical Field
The invention belongs to the field of structural damage calculation, and particularly relates to a deformation cycle damage calculation method.
Background
Since the earthquake action will cause damage to the building structure, and the damage is gradually accumulated along with the increase of the cycle number, the bearing capacity and the residual life of the building structure in the subsequent service period are greatly influenced after the building structure is subjected to the earthquake damage for a plurality of times. And the damage calculation method of the structure under the earthquake action is the theoretical basis of the earthquake-resistant design of the structure, and the internal damage condition of the structure is the important basis for reinforcing the structure after earthquake. Therefore, the method has great significance for the earthquake-resistant design and earthquake damage assessment of the structure by correctly mastering the damage level of the structure under the earthquake action and finding a reasonable calculation method to quantitatively describe the damage degree of the structural member under the earthquake action.
At present, the damage calculation method has the following defects: 1) the existing calculation method is complex, and the definition of the damage starting point is not accordant with the reality; 2) few studies are directed at cyclic damage of the test piece, which is not sufficient to reflect structural damage and damage degree in actual earthquake.
Disclosure of Invention
The invention aims to: aiming at the defects of the prior art, the invention provides the deformation cycle damage calculation method by carrying out statistical analysis on the damage calculation method of the building structure and summarizing the advantages and the disadvantages of the existing damage calculation method.
The technical scheme is as follows: a deformation cycle damage calculation method comprises the following steps:
step 1) establishing a first skeleton curve and a second skeleton curve; the first skeleton curve and the second skeleton curve are determined by a load displacement curve; in the anti-seismic test research, a loading system of first load control and second displacement control can be adopted: loading once under the control of each level of load; under each stage of displacement control, cyclic loading is required for three times; loading the test piece according to the loading system to obtain a load displacement curve; in the displacement control stage, each stage of displacement control is circularly loaded for three times, so that three hysteresis loops are arranged under each stage of displacement control in a load displacement curve;
determining a connecting line of the highest point of the loading hysteresis loop in the load control stage and the highest point of the first hysteresis loop in each stage of displacement control loading as a first skeleton curve, and assuming that the function expression is P ═ f 1 (△ i ) (ii) a Determining a connecting line of the highest point of the loading hysteresis loop in the load control stage and the highest point of the third hysteresis loop in each stage of displacement control loading as a second skeleton curve, and assuming that the function expression is P ═ f 2 (△ i );
Step 2) determining a damage starting point of the test piece, and determining a no-damage slope k according to the damage starting point 1 The non-destructive linear function expression is P ═ k 1 △ i (ii) a Determining a test piece damage point to obtain a load when the test piece is damaged;
step 3) determining the total residual load P under each stage of displacement control Ei Third cycle residual load P Ri Cyclic consumption load P Ci Displacement effective loss load P △i ;P Ei The difference between the bearing capacity of the test piece without damage and the load of the test piece without damage in the same displacement state; p Ri Loading the test piece to the difference between the bearing capacity of the test piece in the third cycle under the ith-level displacement control and the load of the test piece in the damage process; p is Ci For loss of load capacity due to circulationAccumulation is the accumulation of the difference between the first skeleton curve and the second skeleton curve under the control of displacement at each level, i.e. accumulationP △i The loss of load bearing capacity for increased displacement is given by: p △i =P Ei -P Ri -P Ci (ii) a The values of the negative loading and the positive loading are the same;
step 4) determining a damage value D according to a damage calculation formula di 、D Ci And D Ri ;
The method adopts the concept of damage transmission, quantitatively describes the damage caused by displacement increase and the damage caused by load circulation, and has the following calculation formula:
in the formula: d di Controlling damage caused by 'displacement increase' for the ith-level displacement, and is called displacement damage for short; d Ci Damage caused by load circulation in the ith displacement control stage and the previous displacement control stage is referred to as circulation damage for short; d Ri The residual rate of the bearing capacity under the i-th level displacement control is called residual rate for short; the sum of the three is equal to 1.
Further, if the loading initial point is taken as the damage starting point, in the above steps:
the failure point of the test piece in the step 2) is E (delta) u ,0.85P m );P m The peak load is obtained; the breaking point is the load from the peak value P m Down to 0.85P m A point in time; damage by O pointStarting point, if the test piece is not damaged, the load displacement curve will develop along the tangent of the point O of the initial loading point, and the straight line is called as a non-damaged straight line; assuming that the slope of the tangent line at the initial point of the forward loading, i.e. the initial slope of the skeleton curve, is k 1 So the function expression of the intact line is P ═ k 1 △ i (ii) a If the completely damaged test piece is loaded, the load displacement curve of the test piece develops along a straight line OE, and the straight line is called a damage straight line; suppose the slope of the damage line is k 2 ,k 2 =0.85P m /△ u So the functional expression of the damage line is P ═ k 2 △ i (ii) a The initial slope, peak load, failure point and slope of the damage line of the negative skeleton curve are the same as those of the positive calculation method.
P in step 3) Ei =k 1 △ i -k 2 △ i ;P Ri =f 2 (△ i )-k 2 △ i 。
Step 4), the damage value calculation of the ith level displacement control is specifically as follows:
the calculation method of the negative load is the same.
Further, if the damage starting point is customized, the steps are as follows:
determining the peak load P of the skeleton curve in the step 2) m Point of failure E (. DELTA. u ,0.85P m ) The failure point E is the load from the peak value P m Down to 0.85P m A point in time; making a horizontal line from the damage point to cross the skeleton curve at the damage starting point A(Δ 0 ,0.85P m ) If the specimen is not damaged, the load displacement curve develops a line OA, the line OA is called a damage-free line, and the functional expression of the line is assumed to be P ═ k 1 △ i ,k 1 =0.85P m /△ 0 (ii) a The peak load, the damage starting point, the damage point and the slope of the linear elastic straight line of the negative skeleton curve are the same as those of the positive skeleton curve;
p in step 3) Ei =k 1 △ i -0.85P m ;P Ri =f 2 (△ i )-0.85P m ;
Step 4), damage values of ith-stage displacement control are as follows:
has the advantages that: the deformation cycle damage calculation method taking the loading initial point as the damage starting point has the following beneficial effects:
1. based on the two skeleton curves, the initial loading point is taken as a damage starting point, and the total damage value of the damage point is 1, so that the method accords with the actual condition and is suitable for the working condition with larger damage influence in the early stage of component loading;
2. the cyclic damage can be considered and is unified with the reality, and the newly proposed damage line solves the problem that the damage value is not converged at the damage point, makes up the defects of the existing research and provides a new method for the structural damage test research;
the method for calculating the deformation cycle damage of the custom damage starting point has the following beneficial effects:
1. based on the two skeleton curves, the damage starting point is defined by the user according to the damage point, and the total damage value of the damage point is 1, so that the method is more suitable for the working condition with less damage influence in the early stage of loading the component;
2. the cyclic damage can be considered, the defect of cyclic damage research is overcome, the displacement damage and the cyclic damage are unified, the calculation is simpler and more convenient, and a new method is provided for the structural damage experimental research.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a loading regime of the present invention;
FIG. 3 is a schematic view of a load displacement curve according to the present invention;
FIG. 4 is a schematic view of a skeletal curve of the present invention;
FIG. 5 is a schematic diagram of feature points and feature slopes according to embodiment 1 of the present invention;
FIG. 6 is a schematic diagram of a method for calculating damage in embodiment 1 of the present invention;
FIG. 7 is a diagram illustrating feature points and feature slopes according to embodiment 2 of the present invention;
fig. 8 is a schematic diagram of a method for calculating damage in embodiment 2 of the present invention.
Detailed Description
Example 1
A deformation cycle damage calculation method taking a loading initial point as a damage starting point comprises the following steps:
As shown in fig. 4, a connection line between the highest point of the loading hysteresis loop in the load control stage and the highest point of the first hysteresis loop in each stage of displacement control loading is determined as a first skeleton curve, and a function expression of the first skeleton curve is assumed to be P ═ f 1 (△ i ) (ii) a Determining a connecting line of the highest point of the loading hysteresis loop in the load control stage and the highest point of the third hysteresis loop in each stage of displacement control loading as a second skeleton curve, and assuming that the function expression is P ═ f 2 (△ i )。
Step 3, determining the total residual load P under each level of displacement control Ei Third cycle residual load P Ri Cyclic effective consumption load P Ci Displacement effective loss load P △i (ii) a A simplification of the framework curve from fig. 5 with positive loading is shown in fig. 6. P Ei The difference between the bearing capacity of the test piece without damage and the load of the test piece with the same displacement, namely P Ei =k 1 △ i -k 2 △ i ;P Ri The difference between the bearing capacity of the test piece loaded to the ith displacement control in the third cycle and the load in the damage process, namely P Ri =f 2 (△ i )-k 2 △ i ;P Ci For the accumulation of the loss of bearing capacity caused by circulation, the difference between the first skeleton curve and the second skeleton curve under the control of displacement at each stage is accumulated, i.e. the difference is accumulatedP △i For the loss of bearing capacity due to displacement increase, the following formula can be obtained: p △i =P Ei -P Ri -P Ci (ii) a The values of the negative loading and the positive loading are the same.
the method adopts the concept of damage transmission, quantitatively describes the damage caused by displacement increase and the damage caused by load circulation, and has the following calculation formula:
in the formula: d di Controlling damage caused by 'displacement increase' for the ith-level displacement, and is called displacement damage for short; d Ci Damage caused by load circulation in the ith displacement control stage and the previous displacement control stage is referred to as circulation damage for short; d Ri The residual rate of the bearing capacity under the i-th level displacement control is called residual rate for short; the sum of the three is equal to 1.
The damage value of the ith stage displacement control is as follows:
example (a): in the 1 st stage displacement control, the displacement is Δ 1 The displacement damage isThe circulatory impairment isA residual rate of
In the 2 nd stage displacement control, the displacement is△ 2 The displacement damage isThe circulatory impairment isThe residual rate isAnd so on … …
The same applies to the calculation of negative loading.
Example 2
A deformation cycle damage calculation method of a custom damage starting point comprises the following steps:
As shown in fig. 4, the load control phase loading is hystereticDetermining a connecting line between the highest point of the ring and the highest point of the first hysteresis ring in each stage of displacement control loading as a first skeleton curve, and assuming that the function expression is P ═ f 1 (△ i ) (ii) a Determining a connecting line of the highest point of the loading hysteresis loop in the load control stage and the highest point of the third hysteresis loop in each stage of displacement control loading as a second skeleton curve, and assuming that the function expression is P ═ f 2 (△ i )。
Step 3, determining the total residual load P under each level of displacement control Ei Third cycle residual load P Ri Cyclic effective consumption load P Ci Displacement effective loss load P △i ;P Ei The difference between the bearing capacity of the test piece without damage and the load of the test piece with the same displacement, P Ei =k 1 △ i -0.85P m ;P Ri The difference between the bearing capacity of the test piece loaded to the ith displacement control in the third cycle and the load in damage, P Ri =f 2 (△ i )-0.85P m ;P Ci For the accumulation of the loss of bearing capacity caused by circulation, the difference between the first skeleton curve and the second skeleton curve under the control of displacement of each stage is accumulated, i.e. the accumulation is carried outP △i For the loss of bearing capacity due to the displacement increase, the following formula can be used: p △i =P Ei -P Ri -P Ci (ii) a The values of the negative loading and the positive loading are the same;
the method adopts the concept of damage transmission, quantitatively describes the damage caused by displacement increase and the damage caused by load circulation, and has the following calculation formula:
in the formula: d di Controlling damage caused by 'displacement increase' for the ith displacement, and for short, displacement damage; d Ci Controlling damage caused by load circulation for the ith-level displacement, and is called circulation damage for short; d Ri The residual rate of the bearing capacity under the i-th level displacement control is called residual rate for short; the sum of the three is equal to 1.
The damage value of the ith displacement control is as follows:
example (c): in the 1 st stage displacement control, the displacement is Δ 1 The displacement damage isThe circulatory impairment isThe residual rate is
In the case of the 2 nd stage displacement control, the displacement is Δ 2 The displacement damage isThe circulatory impairment isA residual rate ofAnd so on … …
The same applies to the calculation of negative loading.
Claims (7)
1. A deformation cycle damage calculation method is characterized by comprising the following steps:
step 1) establishing a first skeleton curve and a second skeleton curve; the first skeleton curve and the second skeleton curve are determined by a load displacement curve; in the anti-seismic test research, a loading system of first load control and second displacement control is adopted: loading once under the control of each level of load; under each stage of displacement control, cyclic loading is required for three times; loading the test piece according to the loading system to obtain a load displacement curve; in the displacement control stage, each stage of displacement control is circularly loaded for three times, so that three hysteresis loops are arranged under each stage of displacement control in a load displacement curve;
determining a connecting line of the highest point of the loading hysteresis loop in the load control stage and the highest point of the first hysteresis loop in each stage of displacement control loading as a first skeleton curve, wherein the function expression is P ═ f 1 (△ i ) (ii) a Determining a connecting line of the highest point of the loading hysteresis loop in the load control stage and the highest point of the third hysteresis loop in each stage of displacement control loading as a second skeleton curve, wherein the function expression is P ═ f 2 (△ i );
Step 2) determining a damage starting point of the test piece, and determining a no-damage slope k according to the damage starting point 1 The non-destructive linear function expression is P ═ k 1 △ i (ii) a Determining a damage point of the test piece to obtain a load when the test piece is damaged;
step 3) determining the total residual load P under each stage of displacement control Ei Third cycle residual load P Ri Cyclic effective consumption load P Ci Displacement effective consumption load P △i ;P Ei The difference between the bearing capacity of the test piece without damage and the load of the test piece without damage in the same displacement state; p is Ri Loading the test piece to the difference between the bearing capacity of the test piece in the third cycle under the ith-level displacement control and the load of the test piece in the damage process; p Ci For the accumulation of the loss of bearing capacity caused by circulation, the difference between the first skeleton curve and the second skeleton curve under the control of displacement at each stage is accumulated, i.e. the difference is accumulatedP △i The loss of load bearing capacity for increased displacement is given by: p △i =P Ei -P Ri -P Ci (ii) a The values of the negative loading and the positive loading are the same;
step 4) determining a damage value D according to a damage calculation formula di 、D Ci And D Ri ;
The method adopts the concept of damage transmission, quantitatively describes the damage caused by displacement increase and the damage caused by load circulation, and has the following calculation formula:
in the formula: d di Controlling damage caused by 'displacement increase' for the ith-level displacement, and is called displacement damage for short; d Ci Damage caused by load circulation in the ith displacement control stage and the previous displacement control stage is referred to as circulation damage for short; d Ri The residual rate of the bearing capacity under the i-th level displacement control is called residual rate for short; the sum of the three is equal to 1.
2. The deformation cycle damage calculation method of claim 1, wherein: the failure point of the test piece in the step 2) is E (delta) u ,0.85P m );P m The peak load is obtained; the breaking point is the load from the peak value P m Down to 0.85P m A point in time; taking the point O as a damage starting point, if the test piece is not damaged, developing a load displacement curve along a tangent line of the point O at the initial loading point, and calling the straight line as a damage-free straight line; the slope of the tangent line of the initial point of the positive loading, namely the initial slope of the skeleton curve is k 1 So the function expression of the intact line is P ═ k 1 △ i (ii) a If the completely damaged test piece is loaded, the load displacement curve of the test piece develops along a straight line OE, and the straight line is called a damage straight line; the slope of the damage line is k 2 ,k 2 =0.85P m /△ u Therefore, it isThe functional expression of the damage line is P ═ k 2 △ i (ii) a The initial slope, peak load, failure point and slope of the damage straight line of the negative skeleton curve are the same as those of the positive calculation method.
3. The deformation cycle damage calculation method of claim 2, wherein: p in said step 3) Ei =k 1 △ i -k 2 △ i ;P Ri =f 2 (△ i )-k 2 △ i 。
5. the deformation cycle damage calculation method according to claim 1, wherein: determining the peak load P of the skeleton curve in the step 2) m Breaking point E (. DELTA.. delta.) u ,0.85P m ) The failure point E is the load from the peak value P m Down to 0.85P m A point in time; making a horizontal line from the damage point to the ascending section of the skeleton curve at the damage starting point A (delta) 0 ,0.85P m ) If the test piece is not damaged, the load displacement curve develops a straight line OA, the straight line OA is called a damage-free straight line, and the functional expression of the straight line is P ═ k 1 △ i ,k 1 =0.85P m /△ 0 (ii) a The peak load, the damage starting point, the damage point and the slope of the linear elastic straight line of the negative skeleton curve are the same as those of the positive calculation method.
6. The deformation cycle damage calculation method of claim 5, wherein: p in said step 3) Ei =k 1 △ i -0.85P m ;P Ri =f 2 (△ i )-0.85P m 。
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Citations (3)
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CN104020063A (en) * | 2014-06-11 | 2014-09-03 | 西南交通大学 | Method for measuring load threshold of geotechnical packing accumulated deformation state under cyclic loading |
CN107703011A (en) * | 2017-11-27 | 2018-02-16 | 东南大学 | The evaluation method of Porous Elastic Road Surface accumulated damage |
CN108920739A (en) * | 2018-04-27 | 2018-11-30 | 天津大学 | A kind of material constitutive model numerical analysis method considering damage cumulating effect |
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CN104020063A (en) * | 2014-06-11 | 2014-09-03 | 西南交通大学 | Method for measuring load threshold of geotechnical packing accumulated deformation state under cyclic loading |
CN107703011A (en) * | 2017-11-27 | 2018-02-16 | 东南大学 | The evaluation method of Porous Elastic Road Surface accumulated damage |
CN108920739A (en) * | 2018-04-27 | 2018-11-30 | 天津大学 | A kind of material constitutive model numerical analysis method considering damage cumulating effect |
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