CN104655376A - Collision effect analysis method for bridge-track system under action of earthquake - Google Patents

Abstract

The invention discloses a collision effect analysis method for a bridge-track system under the action of earthquake. The collision effect analysis method comprises the following steps: (1) simulating non-linear constrain between a bridge and a track by adopting nonlinear beam elements or spring elements; (2) simulating the secondary dead load of the bridge by adopting a quality unit; (3) simulating a collision behavior of the bridge by adopting a spring to be connected with dampers in parallel and then connected with an interspace in series; (4) establishing steel rails with certain lengths outside the bridge; (5) simulating a sliding support by adopting a nonlinear spring; (6) simulating piers by adopting nonlinear fiber beam elements; (7) simulating the pile-oil interaction through equivalent-stiffness springs; (8) establishing great-quality units and applying acceleration time courses at pier bottoms to carry out uniform or non-uniform excitation. Compared with the prior art, the method considers the influence of a track structure on the earthquake response of the bridge, can analyze the earthquake response of the bridge-track system, and can also research the collision effect among the bridges; the analysis result meets the fact better.

Description

Bridge under geological process-rail system collision effect analytical approach

Technical field

The present invention relates to structural vibration and clash into analytical technology, bridge-rail system collision effect analytical approach under especially a kind of geological process.

Background technology

Current railroad bridge generally lays gapless track, under various loads, between bridge and track, there is nonlinear interaction, bridge structure and the unified system of gapless track Structure composing one.

Continuous print track structure is equivalent to coupling beam device, for bridge provides longitudinal additional restraint on the one hand.On the other hand, track structure is by non-linear hysteresis consumption systems ability.Therefore, when carrying out the Study on Earthquake Dynamic of railroad bridge, the impact of jointless track structure must be considered.

At present, when the dynamic response or collision effect that carry out railroad bridge under geological process are analyzed, mostly do not consider the impact of track structure, this does not meet actual conditions, and its result of calculation exists relatively large deviation.Considering, in the railroad bridge seismic response analysis of track structure, not consider the collision effect of bridge at present, its result of calculation display Liang Tiyi there occurs situation about invading mutually, does not also meet actual conditions.

Therefore, a kind of clear in structure is needed badly and effective bridge-rail system collision effect analytical approach.

Summary of the invention

The technical problem to be solved in the present invention is the deficiency overcoming existing analytical approach, provide a kind of clear in structure, can the bridge-rail system collision effect analytical approach of closing to reality situation.

For solving the problems of the technologies described above, the present invention proposes bridge-rail system collision effect analytical approach under a kind of geological process, comprises the following steps:

(1) bridge and interorbital non-linear constrain is simulated by Nonlinear link element or spring unit;

(2) mass unit simulation bridge secondary dead load is adopted;

(3) collision response of connecting again after adopting spring and damper parallel connection between space simulation bridge;

(4) rail of certain length is respectively set up outward in bridge scope;

(5) non-linear spring simulation sliding support is adopted;

(6) nonlinear fiber beam element simulation bridge pier is adopted;

(7) by the acting in conjunction of equivalent stiffness spring simulation Pile Soil;

(8) by setting up large mass unit and apply Acceleration time course to carry out consistent or non-uniform method at the bottom of pier, bridge-rail system collision effect under geological process is calculated.

Preferably, the bridge in step (1) and the non-linear constrain of interorbital Nonlinear link element or non-linear spring comprise longitudinally, horizontal and vertical three classes.Longitudinal non-linear constrain is taken as ideal elastic-plastic relation.Horizontal non-linear constrain is taken as the nonlinear curve relation obtained by test.Vertical non-linear constrain is taken as ideal elastic-plastic relation or linear relationship.

Preferably, the secondary dead load in step (2) comprises bridge deck pavement, non-fragment orbit or railway ballast, gear Zha Qiang or anti-collision wall, and the quality of the accessory structure of bridge such as railing, cover plate.

Preferably, the collision cell spring rate of step (3) is taken as the flexible rigidity of beam body, and space is taken as the original width of beam seam between beam body, and damping adopts following formula to calculate:

$\begin{array}{cc}c=2\mathrm{\ζ}\sqrt{\frac{{\mathrm{km}}_1{m}_2}{m_1+m_2}}& \mathrm{\ζ}=\frac{-\ln r}{\sqrt{{\left(\ln r\right)}^2+{\mathrm{\π}}^2}}\end{array}$

ζ is damping ratio, and r is coefficient of restitution (concrete material is taken as 0.65), m ₁and m ₂be respectively the quality of collision cell two end carriage body.

Preferably, the roadbed section rail length that step (4) Bridge scope is set up outward is not less than 100m.

Preferably, the non-linear spring adopted in step (5) adopts ideal elastic-plastic method.

Preferably, adopt nonlinear fiber beam element in step (6), concrete adopts Mander MATERIALS METHODS.

Preferably, in step (8), large mass unit quality should be taken as the 1e6 of mass of system doubly, and excitation orientation be along bridge to, direction across bridge or vertically.

Preferably, bridge-rail system adopts Rayleigh damping, and damping ratio is taken as 0.05, and ratio of damping computing method are as follows:

$\begin{array}{cc}\mathrm{\α}=2h\frac{w_1{w}_2}{w_1+w_2}& \mathrm{\β}=2h\frac{1}{w_1+w_2}\end{array}$

Wherein, w ₁and w ₂be the first rank and maximum fundamental frequency is contributed to the longitudinal vibration shape of structure.

Compared with prior art, the invention has the advantages that:

1, bridge and track structure are considered as an organic system, the seismic response rule of Study system;

2, the nonlinear characteristic of track, Liang Ti, bearing, substructure has been taken into full account;

3, the non-elastic collision effect between beam body, between beam body and abutment is considered;

4, clear in structure, is convenient to program and realizes.

Accompanying drawing explanation

Fig. 1 is Bridge of the present invention-rail system collision effect analytical approach schematic diagram.

Fig. 2 is collision effect of the present invention simulation schematic diagram.

Fig. 3 is the time varied curve of beam body and the abutment spacing adopting the present invention to calculate in the embodiment of the present invention.

Fig. 4 is the rail stress envelope diagram adopting the present invention to calculate in the embodiment of the present invention.

Marginal data:

1, the Nonlinear link element between beam body and rail; 2, for simulating the mass unit of secondary dead load; 3, collision cell; 4, roadbed section rail; 5, for simulating the non-linear spring unit of sliding support; 6, nonlinear fiber beam element; 7, equivalent stiffness spring unit at the bottom of pier; 8, large mass unit.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

As shown in Figure 1, bridge under the present embodiment geological process-rail system collision effect analytical approach comprises the steps.

Step one: create track and girder construction.

Rail adopts three-dimensional beam element, and for simplicity, track element length is set to 1m, except the track within the scope of bridge, respectively sets up the track 4 on the long roadbed of 200m at bridge two ends.

Beam body adopts three-dimensional beam element, and cross section property is arranged according to structure actual conditions, and element length is also set to 1m.On beam body unit, conode arranges just arm and lower firm arm.Upper firm arm lengths is taken as the distance of beam body neutral axis to rail neutral axis, and upper firm every meter, arm arranges 1.Lower firm arm is only arranged at beam-ends, and its length is taken as the distance of beam body neutral axis to bearing.Firm arm rigidity is taken as 30 times of beam body rigidity.Upper firm arm top arranges mass unit 2 to simulate bridge secondary dead load.

Step 2: create the non-linear constrain between rail and beam body.

The Nonlinear link element 1 of equal length is shifted to install between rail and beam body respective nodes.The rigidity of bar unit converts according to Axial Resistance, as ideal elastic-plastic Axial Resistance is calculated as follows:

$r=\left\{\begin{array}{cc}24u& u\≤2\mathrm{mm}\\ 48& u>2\mathrm{mm}\end{array}\right.$

Wherein, r represents Axial Resistance, and u is the relative displacement between bridge and rail.

Between rail and beam body respective nodes, arrange the transverse direction of Nonlinear link element simulation fastener and vertical constraint, its rigidity value is with reference to industry standard or test findings simultaneously.

Step 3: set up the non-elastic collision unit 3 between beam body.

Set up between beam body by the collision cell in power transmission space again after spring and damper parallel connection.Fig. 2 shows the structure of collision cell.Wherein, k is taken as beam body axial compression resistance rigidity, and c is damping, and g is the initial separation between beam body.The computing method of damping are as follows:

$\begin{array}{cc}c=2\mathrm{\ζ}\sqrt{\frac{{\mathrm{km}}_1{m}_2}{m_1+m_2}}& \mathrm{\ζ}=\frac{-\ln r}{\sqrt{{\left(\ln r\right)}^2+{\mathrm{\π}}^2}}\end{array}$

Wherein, ζ is damping ratio, and r is coefficient of restitution, m ₁and m ₂be respectively the quality of collision cell two end carriage body.

Step 4: adopt non-linear spring unit 5 to simulate sliding support.

Between lower firm arm node and pier coping portion node, set up longitudinal non-linear spring, spring adopts ideal elastic-plastic method, and friction factor is taken as 0.03.

Step 5: set up bridge pier unit.

According to bridge pier true altitude and section form, nonlinear fiber beam element 6 is adopted to simulate bridge pier.According to actual conditions, give corresponding material properties by fiber element.

Wherein, concrete adopts Mander MATERIALS METHODS, and reinforcing bar adopts Giuffre-Menegotto-Pinto MATERIALS METHODS.

Step 6: set up equivalent stiffness spring unit 7 and simulate Pile Soil acting in conjunction.

Adopt M method to calculate 6 equivalent stiffnesss of multi-column pier foundation, between large mass unit and pier bill kept on file unit, set up 6 equivalent stiffness springs.

Step 7: set up large mass unit 8.

Set up large mass unit at equivalent stiffness spring bottom, element quality is taken as the 1e6 of mass of system doubly.

Step 8: the setting of system damping.

Bridge-rail system adopts Rayleigh damping, and damping ratio is taken as 0.05, and ratio of damping is calculated as follows:

$\mathrm{\α}=2h\frac{w_1{w}_2}{w_1+w_2},\mathrm{\β}=2h\frac{1}{w_1+w_2}$

Wherein α and β is ratio of damping, w ₁and w ₂be the first rank and maximum fundamental frequency is contributed to the longitudinal vibration shape of structure.

Step 9: seismic stimulation mode.

Ground acceleration time-history curves is carried out filtering process, and the sampling time is adjusted to 0.02s, and degree of will speed up time-histories is applied to large mass unit.

By adjustment phase differential, the impact of row wave effect can be considered.Wherein, all large mass units of roadbed section all apply the acceleration-time curve identical with adjacent abutment.

Suppose that Site Type residing for bridge is IV type, Characteristic Site Period is 0.75s, and consider row wave effect, be taken as 200m/s depending on velocity of wave, seismic event peak accelerator is adjusted to 0.57g.The present invention is adopted to calculate 3 across the collision effect of 32m free beam-rail system.Distance between beam body and abutment over time situation is shown in Fig. 3, consider under geological process collide bridge on rail stress envelope diagram see Fig. 4.

The above is only the preferred embodiment of the present invention, and protection scope of the present invention is also not only confined to above-described embodiment.For those skilled in the art, do not departing from the improvement that obtains under the technology of the present invention concept thereof and conversion also should be considered as protection scope of the present invention.

Claims (7)

1. bridge under geological process-rail system collision effect analytical approach, is characterized in that, comprise the following steps:

(1) bridge and interorbital non-linear constrain is simulated by Nonlinear link element or spring unit;

(2) mass unit simulation bridge secondary dead load is adopted;

(3) space is connected again to simulate the collision response between bridge after adopting spring and damper parallel connection;

(4) rail of certain length is respectively set up outward in bridge scope;

(5) non-linear spring simulation sliding support is adopted;

(6) nonlinear fiber beam element simulation bridge pier is adopted;

(7) by the acting in conjunction of equivalent stiffness spring simulation Pile Soil;

(8) by setting up large mass unit and apply Acceleration time course to carry out consistent or non-uniform method at the bottom of pier, bridge-rail system collision effect under geological process is calculated.

2. bridge according to claim 1-rail system collision effect analytical approach, it is characterized in that: the non-linear constrain in step (1) comprises bridge and interorbital along bridge to, direction across bridge and vertical non-linear constrain, and its non-linear constrain parameter is according to current specifications or measured result value.

3. bridge according to claim 1-rail system collision effect analytical approach, it is characterized in that: the collision cell spring rate in step (3) is taken as the flexible rigidity of beam body, space is taken as the original width of beam seam between beam body, and damping adopts following formula to calculate:

$\begin{array}{cc}c=2\mathrm{\ζ}\sqrt{\frac{{\mathrm{km}}_1{m}_2}{m_1+m_2}}& \mathrm{\ζ}=\frac{-1\mathrm{nr}}{\sqrt{{\left(\ln r\right)}^2+{\mathrm{\π}}^2}}\end{array}$

ζ is damping ratio, and r is coefficient of restitution, m ₁and m ₂be respectively the quality of collision cell two end carriage body.

4. bridge according to claim 1-rail system collision effect analytical approach, is characterized in that: the roadbed section rail length that step (4) Bridge scope is set up outward should be not less than 100m.

5. bridge according to claim 1-rail system collision effect analytical approach, is characterized in that: the non-linear spring adopted in step (5) adopts ideal elastic-plastic method.

6. bridge according to claim 1-rail system collision effect analytical approach, is characterized in that: in step (8), large quality point quality should be the 1e6 of mass of system doubly, and excitation orientation be along bridge to, direction across bridge or vertically.

7., according to the arbitrary described bridge-rail system collision effect analytical approach of claim 1-5, it is characterized in that: bridge-rail system adopts Rayleigh damping, and damping ratio is taken as 0.05.