CN117910202A - Steel pipe pile high pile wharf damage state grading method - Google Patents
Steel pipe pile high pile wharf damage state grading method Download PDFInfo
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Abstract
The invention provides a method for grading damage states of a high-pile wharf of a steel pipe pile, which comprises the following steps: 1) Simplifying the wharf structure into a two-dimensional stress analysis model; 2) Simplifying pile-soil interaction and calculating equivalent consolidation depth; 3) Calculating the pile yield bending moment and the plastic hinge length according to the pile body geometric parameters and the material parameters; 4) Calculating the yield bending moment and binding force moment distribution method to obtain the horizontal displacement when the first plastic hinge appears in the elastic deformation stage, and calculating the horizontal displacement limit value of the elastic plastic deformation stage according to the strain limit value of the plastic hinge material and the joint form; 5) And taking the pile top horizontal displacement as a damage state grade judging index, wherein the limit value for dividing different damage state grades is equal to the superposition of the elastic deformation stage horizontal displacement and the elastic plastic deformation stage horizontal displacement limit value. The invention has the advantages of simple operation, convenient calculation and the like, can provide a general calculation theory for the earthquake-proof design of the high-pile wharf, and has stronger engineering applicability.
Description
Technical Field
The invention belongs to the field of displacement capacity analysis in earthquake-resistant design analysis of a high-pile wharf structure, and particularly relates to a steel pipe pile high-pile wharf damage state grading method.
Background
The earthquake load is one of the main damage loads to be considered in the design of the wharf structure, the pile foundation of the high pile wharf can generate different degrees of elastoplastic deformation under the earthquake action, and the plastic hinge area of the pile foundation mostly occurs in pile foundation parts in pile tops and foundation soil. How to judge whether the pile foundation of the high pile wharf is damaged or not and to divide the damage level is the key for ensuring the normal operation of the wharf.
Aiming at the problem, the numerical modeling is widely performed on the wharf structure by using large-scale finite element software at present, the displacement capacity analysis of the wharf is performed by adopting a Pushover method, and whether the wharf is damaged or not and the damage grade is classified is judged by the strain limit value of pile body materials in the numerical software.
Pushover the analysis process is time-consuming and has numerous uncertainty factors, and the fluctuation range of the simulation result is relatively large. Modeling level and boundary condition setting, whether the simulation of the load working condition is real or not and the like can directly influence the final simulation result. Therefore, in addition to the above solutions, there is a need to invent a simple and efficient method of lesion classification.
Disclosure of Invention
In order to solve the problems in the background art, the invention provides a steel pipe pile high pile wharf damage state grading method, which establishes a high pile wharf structure mechanical model by simplifying pile-soil interaction, further simplifies the distance between a pile top plastic hinge and an in-soil plastic hinge based on the high pile wharf structure mechanical model, realizes simplified calculation of horizontal displacement of a pile body in an elastoplastic deformation stage, is beneficial to analyzing the damage state of the high pile wharf and the horizontal displacement rule of a pile body, can improve the theoretical application level of high pile wharf anti-seismic design analysis, and provides a theoretical basis for calculation of the horizontal displacement of the pile body of the high pile wharf structure.
In order to solve the technical problems, the invention provides a steel pipe pile high pile wharf damage state grading method, which mainly comprises the following steps:
1) Determining geometric structure parameters, material parameters and pile body soil layer parameters of a high-pile wharf, selecting a typical cross section, and simplifying a wharf structure into a two-dimensional stress analysis model;
2) Simplifying pile-soil interaction by using an equivalent consolidation method and calculating equivalent consolidation depth;
3) Calculating the pile yield bending moment and the plastic hinge length according to the pile body geometric parameters and the material parameters;
4) Calculating the yield bending moment and binding force moment distribution method to obtain the horizontal displacement when the first plastic hinge appears in the elastic deformation stage, and calculating the horizontal displacement limit value of the elastic plastic deformation stage according to the strain limit value of the plastic hinge material and the joint form;
5) And taking the pile top horizontal displacement as a damage state grade judging index, wherein the limit value for dividing different damage state grades is equal to the superposition of the elastic deformation stage horizontal displacement and the elastic plastic deformation stage horizontal displacement limit value.
The steel pipe pile high pile wharf damage state grading method comprises the following steps of:
1.1 Selecting a typical cross section;
1.2 Simplifying the beam, plate and pile structures into lines;
1.3 The intersection points of the beam, the plate and the pile structures are set to be consolidated;
1.4 Removing the soil body, and replacing the action of the soil on the pile in the mode of pile bottom consolidation.
The steel pipe pile high pile wharf damage state grading method comprises the following steps: in the step 2), complex pile-soil interaction is converted into a mechanical analysis model of a pure structure in a form of calculating equivalent consolidation depth.
The steel pipe pile high pile wharf damage state grading method comprises the following steps: in the step 4), a moment distribution method is adopted to calculate the land side pile top bending moment M.
The steel pipe pile high pile wharf damage state grading method comprises the following steps: in the step 4), the pile top horizontal displacement in the elastoplastic deformation stage is calculated by simplifying the distance from the pile top plastic hinge to the plastic hinge in the soil.
The steel pipe pile high pile wharf damage state grading method comprises the following steps of:
2.1 According to the geometric structure parameter of the pile body, determining the converted width b 0 of the pile body, wherein the calculation process is as follows:
when d is more than or equal to 1.0 m: b 0＝kkf (d+1);
When d < 1.0 m: b 0＝kkf (1.5d+0.5);
Wherein d is the diameter of the pile or the width of the pile perpendicular to the horizontal force acting direction; k is an inter-pile interaction coefficient parallel to the action direction of horizontal force, and 1.0 is taken when the pile group effect is not considered; k f is that a pile shape conversion coefficient round pile or tubular pile is 0.9, and a square pile or rectangular pile is 1.0;
2.2 Calculating the bending rigidity of the pile section according to the geometric structure parameters and the material parameters of the pile body, wherein the bending rigidity=EI; wherein I is a section moment of inertia, and the section moment of inertia of the common pile body is as follows:
Rectangular:
Solid circles:
Hollow circle:
Wherein b is rectangular wide, h is rectangular high, r is the inner diameter of the section of the pile, and d is the outer diameter of the section of the pile; e is the elastic modulus of pile body material, and can adopt the reference value listed in table 4.4.8 in steel structure design standard GB 50017-2017;
2.3 Determining a horizontal resistance coefficient m of the foundation soil at the pile side according to soil layer parameters of the pile body;
2.4 Determining a pile top rotation rigidity coefficient eta according to the connection form of the pile and the panel, taking 1.8-2.2, taking a smaller value when the pile top is hinged or the free length is larger, and taking a larger value when the pile top is not rotated or the free length of the pile is smaller;
2.5 According to the steps 2.1-2.4), calculating the equivalent consolidation depth b, wherein the calculation formula is as follows:
b＝η*T；
Wherein T is the relative stiffness coefficient of the pile, and the calculation formula is as follows:
wherein E is the elastic modulus of the pile material; i is the moment of inertia of the pile section; b 0 is the converted width of the stake.
The steel pipe pile high pile wharf damage state grading method comprises the following specific processes of:
3.1 Calculating the plastic section modulus Z of the pile body according to the geometrical parameters of the pile body;
3.2 Determining the shaft-to-pressure ratio according to the design parameters of the high pile wharf P is the design value of pile shaft axial force, and the axial yield strength of P ye is the axial yield strength;
3.3 Determining that the expected yield strength F ye,Fye of the material is 1.1 times of a yield strength standard value according to the pile body material parameters;
3.4 According to the steps 3.1-3.4), calculating a yield bending moment M y of the pile body, wherein the calculation formula is as follows:
3.5 According to pile body geometric parameters and plastic hinge joint forms, calculating a plastic hinge length L p, wherein the calculation formula is as follows:
Lp＝0.5*d。
The steel pipe pile high pile wharf damage state grading method comprises the following specific processes of:
4.1 Applying rigid arm constraints at each pile top node in a two-dimensional stress analysis model;
4.2 The horizontal unit displacement is applied to the pile tops successively, the shearing force V and the bending moment value M of each pile top are calculated, and the calculation formula is as follows:
wherein l is the length from the pile top to the consolidation point, and delta is the applied horizontal displacement;
4.3 After each time of horizontal unit displacement, the pile top rigid arm constraint from land side to sea side is released one by one, and moment distribution is carried out to calculate the pile top bending moment M of the land side;
4.4 When m=m y, the elastic deformation limit is reached, the application of the horizontal unit displacement is stopped, and the horizontal displacement value is Δ y;
4.5 Determining a strain limit epsilon m according to the plastic hinge form and the material model;
4.6 Determining a section curvature limit value phi m according to a plane section hypothesis and pile body geometric parameters, wherein the calculation formula is as follows:
wherein h is the section height, and if the section is circular, the section outer diameter is the section outer diameter;
4.7 Calculating the section yield curvature phi y according to the yield bending moment and the geometric parameters of the pile body, wherein the calculation formula is as follows:
wherein M y is the yield bending moment of the pile body, E is the elastic modulus of the pile material, and I is the moment of inertia of the pile section;
4.8 Simplifying and equating the plastic hinge distance H from the pile top to the plastic hinge in the soil to be the sum of the exposed soil depth a of the land side pile and the equivalent consolidation depth b, namely H=a+b;
4.9 According to the steps 4.5) -4.8), calculating a pile top horizontal displacement limit delta p,m in the elastoplastic deformation stage of the high pile wharf, wherein the calculation formula is as follows:
Δp,m＝θp,m×H；
θp,m＝LpΦp,m＝Lp(Φm-Φy)；
Where the strain limit ε m is determined by three seismic levels as ε OLE,εCLE,εDE, then Δ p,m may be subdivided into three levels of Δ p,OLE,Δp,CLE,Δp,DE.
The method for grading the damage state of the high pile wharf of the steel pipe pile, wherein the calculation process of the land side pile top bending moment M in the step 4.3) is as follows:
4.3.1 Calculating the linear rigidity i=EI/l of each pile body, each beam and each plate;
4.3.2 Calculating the rotation rigidity coefficients of each rod piece, wherein the rotation rigidity is S=4i;
4.3.3 Calculating the transfer coefficient of each beam and each plate;
4.3.4 Calculating a distribution coefficient mu, a distribution coefficient
4.3.5 A) calculating a distribution bending moment, namely a distribution bending moment M F＝μ*(-Mu), wherein M u is a solid end bending moment, namely M 1～Mn, and n piles are assumed;
4.3.6 Calculating a transmission bending moment
4.3.7 Calculating pile top bending moment, sequentially releasing each solid end bending moment from 1 to n, distributing the solid end bending moment of only one pile top at a time, and keeping the other pile tops in a consolidation state;
4.3.8 Repeating the steps to perform distribution calculation until the sum of bending moment values of all sides of the pile top node is0, and completing moment distribution;
4.3.9 Land side pile top bending moment m=m u+MF+Mc.
By adopting the technical scheme, the invention has the following beneficial effects:
The method for classifying the damaged state of the high-pile wharf of the steel pipe pile has reasonable conception, has the advantages of simplicity in operation, convenience in calculation and the like, can provide a general calculation theory for the anti-seismic design of the high-pile wharf, has stronger engineering applicability, and can be conveniently used for calculating the displacement capacity of the high-pile wharf and rapidly judging the damaged state classification of the high-pile wharf.
According to the invention, the pile-soil interaction is simplified to establish the mechanical model of the high-pile wharf structure, the distance between the plastic hinge at the pile top and the plastic hinge in the soil is further simplified based on the mechanical model, the simplified calculation of the horizontal displacement of the pile body in the elastoplastic deformation stage is realized, and the analysis of the damage state of the high-pile wharf and the horizontal displacement rule of the pile body is facilitated, so that the theoretical application level of the high-pile wharf anti-seismic design analysis can be improved, and a theoretical basis is provided for the calculation of the horizontal displacement of the pile body of the high-pile wharf structure.
The calculation result of the invention is verified with the numerical simulation result for many times, so that the reliability of the invention is verified, and the invention plays a good reference role in the damage classification of the high pile wharf after an earthquake.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings which are required in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are some embodiments of the invention and that other drawings may be obtained from these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for grading damage states of a high pile wharf of a steel pipe pile;
FIG. 2 is a cross-sectional view of a steel pipe pile high pile wharf involved in the steel pipe pile high pile wharf damage status grading method of the invention;
Fig. 3 is an equivalent consolidation schematic diagram of a high pile wharf, which is involved in the classification method of the damaged state of the high pile wharf of the steel pipe pile;
Fig. 4 is a schematic diagram of the relationship between the horizontal force and the horizontal displacement force of the high pile wharf and the displacement, which are involved in the classification method of the damaged state of the high pile wharf of the steel pipe pile;
fig. 5 is a schematic diagram of a high pile wharf moment distribution method involved in the classification method of the damaged state of the high pile wharf of the steel pipe pile.
Fig. 6 is a diagram of a calculation process of plastic section modulus of steel piles in different section forms, which is involved in the classification method of the damage state of a high pile wharf of the steel pipe pile.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention is further illustrated with reference to specific embodiments.
As shown in fig. 2, the method for classifying the damaged state of the high pile wharf of the steel pipe pile provided by the embodiment performs theoretical mechanical analysis on the wharf structure after simplifying pile-soil interaction, and further simplifies the distance between the plastic hinge at the pile top and the plastic hinge in the soil based on the theoretical mechanical analysis, so as to realize simplified calculation of the horizontal displacement of the pile body in the elastoplastic deformation stage. The relation between the pile top horizontal displacement and the damage state grade of the high pile wharf is deduced, and the method specifically comprises the following steps:
1) Determining geometric structure parameters, material parameters and pile body soil layer parameters of a high pile wharf, selecting a typical cross section, and simplifying the wharf structure into a two-dimensional stress analysis model, wherein the specific process is as follows, as shown in fig. 3:
1.1 Selecting a typical cross section;
1.2 Simplifying the beam, plate and pile structures into lines;
1.3 The intersection points of the beam, the plate and the pile structures are set to be consolidated;
1.4 Removing the soil body, and replacing the action of the soil on the pile in the mode of pile bottom consolidation.
2) Simplifying pile-soil interaction by using an equivalent consolidation method and calculating equivalent consolidation depth; the specific process is as follows:
2.1 According to the geometric structure parameter of the pile body, determining the converted width b 0 of the pile body, wherein the calculation process is as follows:
when d is more than or equal to 1.0 m: b 0＝kkf (d+1);
When d < 1.0 m: b 0＝kkf (1.5d+0.5);
Wherein d is the diameter of the pile or the width (m) of the pile perpendicular to the horizontal force acting direction; k is an inter-pile interaction coefficient parallel to the action direction of horizontal force, and 1.0 is taken when the pile group effect is not considered; k f is that a pile shape conversion coefficient round pile or tubular pile is 0.9, and a square pile or rectangular pile is 1.0;
2.2 Calculating the bending rigidity of the pile section according to the geometric structure parameters and the material parameters of the pile body, wherein the bending rigidity=EI; wherein I is a section moment of inertia, and the section moment of inertia of the common pile body is as follows:
i is a section moment of inertia (m 4), and the section moment of inertia of a common pile body is as follows:
Rectangular:
Solid circles:
Hollow circle:
Wherein b is rectangular wide, h is rectangular high, r is the inner diameter of the section of the pile, and d is the outer diameter of the section of the pile; e is the elastic modulus (kN/m 2) of pile body material, and can adopt the reference values listed in table 4.4.8 in steel structure design standard (GB 50017-2017);
2.3 The horizontal resistance coefficient m of the foundation soil at the pile side is determined according to the soil layer parameters of the pile body, and the determination process is as follows: selecting a corresponding m value from table 1 according to the liquid limit index, the pore ratio and the soil layer type of the soil layer in the geological survey report;
TABLE 1 m value of non-rock soil
Note that: in the ① table, I L is a liquid limit index, and e is a pore ratio; ② When the horizontal displacement is larger than the tabulated value, the m value should be properly reduced, and when the horizontal displacement is smaller than the tabulated value, the m value can be properly increased; ③ When the mud surface is an inclined surface, the m value should be properly reduced; ④ The m value should be multiplied by 0.4 to reduce the tabulated value when the horizontal force is a long-term load; ⑤ When the foundation is a liquefiable soil layer, the corresponding coefficient in the table 5.3.12 of the building pile foundation technical specification (JGJ 94-2008) should be multiplied by the table numerical value
2.4 Determining a pile top rotation rigidity coefficient eta according to the connection form of the pile and the panel, taking 1.8-2.2, taking a smaller value when the pile top is hinged or the free length is larger, and taking a larger value when the pile top is not rotated or the free length of the pile is smaller;
2.5 According to said steps 201-204), the equivalent consolidation depth b is calculated according to the following formula:
b＝η*T；
wherein T is the relative stiffness coefficient (m) of the pile, and the calculation formula is as follows:
Wherein E is the elastic modulus (kN/m 2) of the pile material; i is the moment of inertia of the pile cross section (m 4);b0 is the converted width (m) of the pile.
3) Calculating the pile yield bending moment and the plastic hinge length according to the pile body geometric parameters and the material parameters; the specific process is as follows:
3.1 According to the geometric parameters of the pile body, calculating the plastic section modulus Z of the pile body, wherein the calculation process is shown in figure 6;
3.2 Determining the shaft-to-pressure ratio according to the design parameters of the high pile wharf P is the design value of pile shaft axial force, and the axial yield strength of P ye can be the reference value listed in Table 4.4.1 in steel structure design standard (GB 50017-2017);
3.3 Determining that the expected yield strength F ye,Fye of the material is 1.1 times of a yield strength standard value according to the pile body material parameters; the reference values listed in table 4.4.1 in the steel structure design standard (GB 50017-2017) can be adopted;
3.4 According to the steps 301-304), the yield bending moment M y of the pile body is calculated, and the calculation formula of the yield bending moment M y of the pile body is as follows:
3.5 According to pile body geometric parameters and plastic hinge joint forms, calculating a plastic hinge length L p, wherein the calculation formula is as follows:
Lp＝0.5*d。
4) Calculating the yield bending moment and binding force moment distribution method to obtain the horizontal displacement when the first plastic hinge appears in the elastic deformation stage, and calculating the horizontal displacement limit value of the elastic plastic deformation stage according to the strain limit value of the plastic hinge material and the joint form; the specific process is as follows:
4.1 Applying rigid arm constraints at each pile top node in a two-dimensional stress analysis model;
4.2 The horizontal unit displacement is applied to the pile tops successively, the shearing force V and the bending moment value M of each pile top are calculated, and the calculation formula is as follows:
wherein l is the length from the pile top to the consolidation point, and delta is the applied horizontal displacement (m);
4.3 After each time of horizontal unit displacement is applied, pile top rigid arm constraints from land side to sea side are released one by one, moment distribution is carried out, and the pile top bending moment M on the land side is calculated, wherein the calculation process is as follows:
4.3.1 Calculating the linear rigidity i=EI/l of each pile body, each beam and each plate;
4.3.2 Calculating the rotation rigidity coefficient of each rod piece;
after the structure of the high pile wharf is simplified, the pile bottom is consolidated, and the pile top is constrained by the rigid arm in the analysis process, so that the far-end support is consolidated; the rotational stiffness is s=4i;
4.3.3 Calculating the transfer coefficient of each beam and each plate;
after the structure of the high pile wharf is simplified, the transfer coefficients are 1/2;
4.3.4 Calculating a distribution coefficient mu, a distribution coefficient
4.3.5 Calculating a distribution bending moment, M F＝μ*(-Mu), wherein M u is a solid end bending moment (namely M 1～Mn), and n piles are assumed;
4.3.6 Calculating a transmission bending moment
4.3.7 Calculating pile top bending moment, sequentially releasing each solid end bending moment from 1 to n, distributing the solid end bending moment of only one pile top at a time, and keeping the other pile tops in a consolidation state;
4.3.8 Repeating the steps to perform distribution calculation until the sum of bending moment values of all sides of the pile top node is0, and completing moment distribution;
4.3.9 Land side pile top bending moment m=m u+MF+Mc;
4.4 When m=m y, the elastic deformation limit is reached, the application of the horizontal unit displacement is stopped, and the horizontal displacement value is Δ y;
4.5 Strain limits epsilon m were determined based on plastic joint form and material model, and the material strain limits at three seismic levels referenced Port of Long Beach WHARF DESIGN CRITERIA (version 5.0) are shown in table 3:
TABLE 3 Plastic hinge material strain limits
Note that: epsilon c is the concrete strain, epsilon s is the steel strain, epsilon smd is the strain limit value of the pin steel bar, and rho s is the volume stirrup rate of the stirrup.
4.6 Determining a section curvature limit value phi m according to a plane section hypothesis and pile body geometric parameters, wherein the calculation formula is as follows:
wherein h is the section height, and if the section is circular, the section outer diameter is the section outer diameter;
4.7 Calculating the section yield curvature theta y according to the yield bending moment and the pile body geometric parameters, wherein the calculation formula is as follows:
wherein M y is obtained in step 3.4);
4.8 Simplifying and equating the plastic hinge distance H from the pile top to the plastic hinge in the soil to the sum of the exposed soil depth a of the land side pile and the equivalent consolidation depth b, as shown in figures 3 and 4,
H＝a+b；
4.9 According to said steps 4.5) -4.8), the pile top horizontal displacement limit delta p,m at the stage of elastoplastic deformation of the high pile wharf is calculated as follows:
Δp,m＝θp,m×H；
θp,m＝LpΦp,m＝Lp(Φm-Φy)；
Where the strain limit ε m is determined by three seismic levels as ε OLE,εCLE,εDE, then Δ p,m may be subdivided into three levels of Δ p,OLE,Δp,CLE,Δp,DE.
5) And taking the pile top horizontal displacement as a damage state grade judging index, wherein the limit value for dividing different damage state grades is equal to the superposition of the elastic deformation stage horizontal displacement and the elastic plastic deformation stage horizontal displacement limit value.
As shown in fig. 2, the present embodiment uses an actual high pile wharf as a calculation example, and for example, according to the measurement result, the main structural parameters and material parameters of the high pile wharf are shown in table 4:
Table 4 example high pile wharf Structure and Material parameter Table
As shown in fig. 3, the dock structure is simplified into a two-dimensional stress analysis model;
The soil layer is sandy soil, and the horizontal resistance coefficient m of the soil layer is 6000kN/m 4 according to the design specification of pile foundation of water transport engineering (JTS 147-7-2022);
The pile top rotation coefficient eta takes 1.8-2.2, the pile top is hinged or takes a smaller value when the free length is larger, and the pile top does not rotate or takes a larger value when the free length of the pile is smaller;
the steel pipe pile and the cross beam are fixedly connected, and the pile top rotation coefficient eta is 2.2;
First, the equivalent consolidation depth b is calculated as follows:
b＝η*T；
Where T is the relative stiffness coefficient (m) of the pile, calculated as follows:
e is the elastic modulus (kN/m 2) of the pile material; i is the moment of inertia of the pile cross section (m 4);b0 is the converted width (m) of the pile), calculated as follows:
when d is more than or equal to 1.0 m: b 0＝kkf (d+1);
When d < 1.0 m: b 0＝kkf (1.5d+0.5);
wherein d is the diameter of the pile or the width (m) of the pile perpendicular to the horizontal force acting direction;
The equivalent consolidation depth b was calculated to be 4.1m.
Then, pile body yield bending moment M y is calculated as follows:
Wherein F ye is the expected yield strength of the material, the standard value of the yield strength of Q345 type steel is 345MPa, and F ye is 1.1 times the standard value of the yield strength;
Is an axial pressure ratio, and the value is 0.3;
Z is the modulus of plastic section, calculated as follows:
Z＝td2 (t＜＜d)；
wherein t is the wall thickness of the section of the pile body.
The calculated value of the pile body yield bending moment M y is 2379 kN.m;
The plastic hinge length L p is calculated as follows:
Lp＝0.5*d；
Then, as shown in fig. 4, solving pile top horizontal displacement delta y when the elastic deformation of the pile body reaches the limit and calculating pile top horizontal displacement limit delta p,m in the high pile wharf elastic-plastic deformation stage;
as shown in fig. 5, rigid arm constraint is applied to the pile top of the wharf structure, and mechanical analysis is performed;
the first step, calculate each pile bolck shear force and rigidity constraint bending moment, calculate as follows:
pile top horizontal force F is calculated as follows:
Wherein n is the number of piles in a row; v 1～V6 is the shear force value when each pile top generates a corresponding horizontal displacement delta, and is calculated as follows:
Wherein l is the length from the pile top to the consolidation point;
Similarly, the stiffness constraint bending moment M 1～M6 is calculated as follows:
And secondly, adopting a moment distribution method, and calculating as follows:
Calculating the linear rigidity i=EI/l of each pile body, each beam and each plate;
calculating the rotation rigidity coefficient of each rod piece;
After the structure of the high pile wharf is simplified, the pile bottom is consolidated, and the pile top is constrained by the rigid arm in the analysis process, so that the far-end support is consolidated. The rotational stiffness is s=4i;
Calculating the transfer coefficient of each beam and each plate;
after the structure of the high pile wharf is simplified, the transfer coefficients are 1/2;
calculating distribution coefficient mu, distribution coefficient
Calculating a distribution bending moment, a distribution bending moment M F＝μ*(-Mu), wherein M u is a solid end bending moment (namely M 1～M6);
Calculating a transmission bending moment
Calculating pile top bending moment, sequentially releasing each solid end bending moment from 1 to 6, distributing the solid end bending moment of only one pile top at a time, and keeping the other pile tops in a consolidation state;
and repeating the steps to perform distribution calculation until the sum of bending moment values of all sides of the pile top node is 0, thereby completing moment distribution.
Pile top bending moment m=m u+MF+Mc;
Let m=m y, substituting into moment distribution method, pile top horizontal displacement Δ y calculated value is 0.055M;
Thirdly, determining the strain limit value of the pile top plastic hinge material, wherein the related specifications are not available for reference due to different anti-seismic design concepts of the current Chinese building;
the material strain limits ε m for the three states referenced Port of Long Beach WHARF DESIGN CRITERIA (version 5.0) are:
Minimum damage, steel strain limit 0.015; controllable restoration, wherein the strain limit value of the steel is 0.06; life safety, strain limit 0.08;
For example, a steel pipe pile, the strain limit is chosen to be epsilon OLE＝0.015,εCLE＝0.06,εDE =0.08;
as shown in fig. 4, the pile top horizontal displacement limit Δ p,m in the elastoplastic deformation stage is calculated as follows:
Δp,m＝θp,m×H；
θp,m＝LpΦp,m＝Lp(θm-Φy)；
Finally, delta c＝Δy+Δp,m is used as a damage state grade limit value of the high pile wharf of the steel pipe pile;
The calculation of Δ c is: minimum damage, 0.11m; controllable repair, 0.35m; life safety, 0.46m;
The calculation result is as follows: Δ c,OLE＝0.11m;Δc,CLE＝0.35m;Δc,DE =0.46 m.
According to the invention, the pile-soil interaction is simplified to establish the mechanical model of the high-pile wharf structure, the distance between the plastic hinge at the pile top and the plastic hinge in the soil is further simplified based on the mechanical model, the simplified calculation of the horizontal displacement of the pile body in the elastoplastic deformation stage is realized, and the analysis of the damage state of the high-pile wharf and the horizontal displacement rule of the pile body is facilitated, so that the theoretical application level of the high-pile wharf earthquake-resistant design analysis can be improved, and a theoretical basis is provided for evaluating the earthquake vulnerability and toughness capacity of the pile body of the high-pile wharf structure.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (9)
1. The method for grading the damage state of the high pile wharf of the steel pipe pile is characterized by mainly comprising the following steps of:
1) Determining geometric structure parameters, material parameters and pile body soil layer parameters of a high-pile wharf, selecting a typical cross section, and simplifying a wharf structure into a two-dimensional stress analysis model;
2) Simplifying pile-soil interaction by using an equivalent consolidation method and calculating equivalent consolidation depth;
3) Calculating the pile yield bending moment and the plastic hinge length according to the pile body geometric parameters and the material parameters;
4) Calculating the yield bending moment and binding force moment distribution method to obtain the horizontal displacement when the first plastic hinge appears in the elastic deformation stage, and calculating the horizontal displacement limit value of the elastic plastic deformation stage according to the strain limit value of the plastic hinge material and the joint form;
5) And taking the pile top horizontal displacement as a damage state grade judging index, wherein the limit value for dividing different damage state grades is equal to the superposition of the elastic deformation stage horizontal displacement and the elastic plastic deformation stage horizontal displacement limit value.
2. The method for grading the damage state of a high pile wharf of a steel pipe pile according to claim 1, wherein the simplification process of the two-dimensional stress analysis model is as follows:
1.1 Selecting a typical cross section;
1.2 Simplifying the beam, plate and pile structures into lines;
1.3 The intersection points of the beam, the plate and the pile structures are set to be consolidated;
1.4 Removing the soil body, and replacing the action of the soil on the pile in the mode of pile bottom consolidation.
3. The steel pipe pile high pile wharf damage state grading method of claim 1, wherein the method comprises the following steps: in the step 2), complex pile-soil interaction is converted into a mechanical analysis model of a pure structure in a form of calculating equivalent consolidation depth.
4. The steel pipe pile high pile wharf damage state grading method of claim 1, wherein the method comprises the following steps: in the step 4), a moment distribution method is adopted to calculate the land side pile top bending moment M.
5. The steel pipe pile high pile wharf damage state grading method of claim 1, wherein the method comprises the following steps: in the step 4), the pile top horizontal displacement in the elastoplastic deformation stage is calculated by simplifying the distance from the pile top plastic hinge to the plastic hinge in the soil.
6. The method for grading the damage state of the high pile wharf of the steel pipe pile according to claim 1, wherein the calculating process of the equivalent consolidation depth in the step 2) is as follows:
2.1 According to the geometric structure parameter of the pile body, determining the converted width b 0 of the pile body, wherein the calculation process is as follows:
when d is more than or equal to 1.0 m: b 0＝kkf (d+1);
When d < 1.0 m: b 0＝kkf (1.5d+0.5);
Wherein d is the diameter of the pile or the width of the pile perpendicular to the horizontal force acting direction; k is an inter-pile interaction coefficient parallel to the action direction of horizontal force, and 1.0 is taken when the pile group effect is not considered; k f is that a pile shape conversion coefficient round pile or tubular pile is 0.9, and a square pile or rectangular pile is 1.0;
2.2 Calculating the bending rigidity of the pile section according to the geometric structure parameters and the material parameters of the pile body, wherein the bending rigidity=EI; wherein I is a section moment of inertia, and the section moment of inertia of the common pile body is as follows:
Rectangular:
Solid circles:
Hollow circle:
Wherein b is rectangular wide, h is rectangular high, r is the inner diameter of the section of the pile, and d is the outer diameter of the section of the pile; e is the elastic modulus of pile body material, and can adopt the reference value listed in table 4.4.8 in steel structure design standard GB 50017-2017;
2.3 Determining a horizontal resistance coefficient m of the foundation soil at the pile side according to soil layer parameters of the pile body;
2.4 Determining a pile top rotation rigidity coefficient eta according to the connection form of the pile and the panel, taking 1.8-2.2, taking a smaller value when the pile top is hinged or the free length is larger, and taking a larger value when the pile top is not rotated or the free length of the pile is smaller;
2.5 According to the steps 2.1-2.4), calculating the equivalent consolidation depth b, wherein the calculation formula is as follows:
b＝η*T；
Wherein T is the relative stiffness coefficient of the pile, and the calculation formula is as follows:
wherein E is the elastic modulus of the pile material; i is the moment of inertia of the pile section; b 0 is the converted width of the stake.
7. The method for grading the damage state of the high pile wharf of the steel pipe pile according to claim 1, wherein the specific process of the step 3) is as follows:
3.1 Calculating the plastic section modulus Z of the pile body according to the geometrical parameters of the pile body;
3.2 Determining the shaft-to-pressure ratio according to the design parameters of the high pile wharf P is the design value of pile shaft axial force, and the axial yield strength of P ye is the axial yield strength;
3.3 Determining that the expected yield strength F ye,Fye of the material is 1.1 times of a yield strength standard value according to the pile body material parameters;
3.4 According to the steps 3.1-3.4), calculating a yield bending moment M y of the pile body, wherein the calculation formula is as follows:
3.5 According to pile body geometric parameters and plastic hinge joint forms, calculating a plastic hinge length L p, wherein the calculation formula is as follows:
Lp＝0.5*d。
8. the method for grading the damage state of the high pile wharf of the steel pipe pile according to claim 7, wherein the specific process of the step 4) is as follows:
4.1 Applying rigid arm constraints at each pile top node in a two-dimensional stress analysis model;
4.2 The horizontal unit displacement is applied to the pile tops successively, the shearing force V and the bending moment value M of each pile top are calculated, and the calculation formula is as follows:
wherein l is the length from the pile top to the consolidation point, and delta is the applied horizontal displacement;
4.3 After each time of horizontal unit displacement, the pile top rigid arm constraint from land side to sea side is released one by one, and moment distribution is carried out to calculate the pile top bending moment M of the land side;
4.4 When m=m y, the elastic deformation limit is reached, the application of the horizontal unit displacement is stopped, and the horizontal displacement value is Δ y;
4.5 Determining a strain limit epsilon m according to the plastic hinge form and the material model;
4.6 Determining a section curvature limit value phi m according to a plane section hypothesis and pile body geometric parameters, wherein the calculation formula is as follows:
wherein h is the section height, and if the section is circular, the section outer diameter is the section outer diameter;
4.7 Calculating the section yield curvature phi y according to the yield bending moment and the geometric parameters of the pile body, wherein the calculation formula is as follows:
Wherein M y is the yield bending moment of the pile body, E is the elastic modulus of the pile material, and I is the moment of inertia of the pile section;
4.8 Simplifying and equating the plastic hinge distance H from the pile top to the plastic hinge in the soil to be the sum of the exposed soil depth a of the land side pile and the equivalent consolidation depth b, namely H=a+b;
4.9 According to the steps 4.5) -4.8), calculating a pile top horizontal displacement limit delta p,m in the elastoplastic deformation stage of the high pile wharf, wherein the calculation formula is as follows:
Δp,m＝θp,m×H；
θp,m＝LpΦp,m＝Lp(Φm-Φy)；
Where the strain limit ε m is determined by three seismic levels as ε OLE,εCLE,εDE, then Δ p,m may be subdivided into three levels of Δ p,OLE,Δp,CLE,Δp,DE.
9. The method for grading the damage state of a high pile wharf of a steel pipe pile according to claim 8, wherein the calculation process of the land side pile top bending moment M of step 4.3) is as follows:
4.3.1 Calculating the linear rigidity i=EI/l of each pile body, each beam and each plate;
4.3.2 Calculating the rotation rigidity coefficients of each rod piece, wherein the rotation rigidity is S=4i;
4.3.3 Calculating the transfer coefficient of each beam and each plate;
4.3.4 Calculating a distribution coefficient mu, a distribution coefficient
4.3.5 A) calculating a distribution bending moment, namely a distribution bending moment M F＝μ*(-Mu), wherein M u is a solid end bending moment, namely M 1～Mn, and n piles are assumed;
4.3.6 Calculating a transmission bending moment
4.3.7 Calculating pile top bending moment, sequentially releasing each solid end bending moment from 1 to n, distributing the solid end bending moment of only one pile top at a time, and keeping the other pile tops in a consolidation state;
4.3.8 Repeating 4.3.7) to perform distribution calculation until the sum of bending moment values of all sides of the pile top node is 0, and completing moment distribution;
4.3.9 Land side pile top bending moment m=m u+MF+Mc.
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