CN103577652A - Cross-sea bridge wind barrier designing method - Google Patents

Abstract

The invention belongs to the technical field of structural engineering, and particularly relates to a cross-sea bridge wind barrier designing method. A bridge floor wind speed field model with a wind barrier and a bridge floor wind speed field model without the wind barrier are established respectively by combining wind tunnel tests and numerical wind tunnels, the simulated height and simulated ventilation ratio of the wind barrier in the bridge floor wind speed field models are changed constantly, the bridge floor equivalent wind speed and the wind speed reduction factor are calculated and compared with the traffic safety wind speed of typical vehicle types, and the height and the ventilation ratio of the wind barrier in safety are the height and the ventilation ratio of the wind barrier needing to be designed. According to the cross-sea bridge wind barrier designing method, when the wind barrier of a cross-sea bridge is designed, conventional factors are taken into consideration, and the influences of multiple wind directions and the influences of multiple bridge types are also proposed to be taken into consideration. Meanwhile, the measure of combining the wind tunnel tests and the numerical wind tunnels is adopted to determine the wind speed fields and obtain the height and the ventilation ratio of the wind barrier, the wind barrier is then designed, and thus the designed wind barrier is more reasonable, more economical, and capable of practically meeting the engineering requirements and powerfully ensuring traffic safety.

Description

Bridge spanning the sea wind barrier method for designing

Technical field

The invention belongs to technical field of structural engineering, be specifically related to a kind of bridge spanning the sea wind barrier method for designing.

Background technology

Along with scientific and technical development, for promoting straits economic construction, the bridge spanning the sea of convenient traffic corridor can be provided, Yi China and obtain swift and violent development all over the world, in order to avoid deep water foundation and the navigation requirement that meets large ship, long-span bridge girder construction will become the strong rival of engineering construction scheme over strait with the combination of marine long bridge, yet the residing special natural wind environment of Oversea bridge tends to the traffic safety of super-span bridge to cause totally unfavorable impact.

If automobile is subject to side wind action in the process of moving, may break away, the safety problem such as inclination, affect the safety traffic of vehicle.Especially the automobile travelling on ultra-large type bridge, due to factors such as bridge elevation, the acceleration of structure flow-disturbing, makes wind become particularly outstanding to the problem that affects of vehicle safety travel.Wind also shows that on the impact of traffic safety charming appearance and behaviour accident causes long traffic jam.

Wind barrier is the Main Means that solves bridge floor traffic safety and comfortableness problem, and especially, under extreme crosswind effect, wind barrier can effectively guarantee the security that light vehicle travels.Determine that in science of bridge building, whether adopting wind barrier is a complicated problem, its requires to consider natural wind condition, vehicle launch performance, bridge structure wind resisting stability, and the composite factor such as traffic engineering management, and wherein some factor may be conflicted mutually.The bridge spanning the sea wind barrier designing technique of current domestic employing is mainly considered the impact of the conventional factors such as wind speed, wind direction, not deep enough to the windy synthetic study to many bridge types, is difficult to accomplish the economical rationality that gears to actual circumstances,

In sum, wind barrier has very important significance on impact research of vehicle driving safety, how to design wind barrier and considers that many factors is current problem demanding prompt solution.

Summary of the invention

Object of the present invention is exactly the deficiency existing in order to solve above-mentioned background technology, the bridge spanning the sea wind barrier method for designing that provides a kind of test from the many bridge types of appropriate design to impact that consider windy to combine with Numerical Wind Tunnel.

The technical solution used in the present invention is: a kind of bridge spanning the sea wind barrier method for designing, comprises the following steps:

(1), by wind tunnel test and Numerical Wind Tunnel set up respectively, bridge floor wind speed field model during calm barrier, analyze bridge floor wind speed field, the two mutually combines, verifies, compares, and constantly changes height and the ventilative rate of the wind barrier of simulating in bridge floor wind speed field model simultaneously;

(2) bridge floor equivalent wind speed and wind speed reduction coefficient, while calculating vehicle by bridge floor wind speed field model, and compare with the traffic safety wind speed of typical vehicle;

(3), in bridge floor equivalent wind speed and wind speed reduction coefficient, when calculating vehicle by bridge floor wind speed field model, record height and the ventilative rate of in bridge floor wind speed field model, simulating wind barrier;

(4), by the vehicle calculating, by the bridge floor equivalent wind speed of bridge floor wind speed field model, compare with the traffic safety wind speed of typical vehicle with wind speed reduction coefficient, judge to simulate have whether safety of the bridge floor wind speed field model of wind barrier;

(5) if judge in step (4), simulation has the bridge floor wind speed field model of wind barrier is safe, the height of wind barrier and height and the ventilative rate of the wind barrier that ventilative rate is required design now simulated; Otherwise repeating step (1)-(4);

(6) height of the wind barrier, obtaining according to simulation and ventilative rate are designed qualified wind barrier.

Further, the parameter combining in the bridge floor wind speed field model of setting up by wind tunnel test and Numerical Wind Tunnel in described step (1) comprises different automobile types, different road surface, different load-carrying, different bridge type and their combination in any.

Further, the equivalent wind speed computing formula in described step (2) is:

or $V_{\mathrm{eq}}={\left[\frac{1}{Z_e}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\left(V\left(z_i\right)\right)}^2{z}_i\right]}^{1/2}$

Wherein: V (z) and V (z _i) be respectively bridge floor height z and z _ithe side direction incoming flow wind speed at place; Z _ealtitude range for automobile; N is along automobile height measuring point quantity.

Further, the equivalent wind speed that in described step (2), wind speed reduction coefficient is bridge floor and the ratio of actual side direction incoming flow wind speed.

The present invention is when the wind barrier of design bridge spanning the sea, not only consider conventional factor, and it is windy to the impact with many bridge types to propose consideration, meanwhile, the means that adopt wind tunnel test and Numerical Wind Tunnel to combine are determined bridge floor wind speed field, obtain height and two parameters of ventilative rate of air-out barrier, and then design wind barrier, the wind barrier of designing is like this more reasonable, more economical, engineering demands effectively, powerful guarantee traffic safety.

Accompanying drawing explanation

Fig. 1 is wind barrier parameter designing schematic diagram of the present invention.

Fig. 2 is the computation model main body figure of typical bridge section I

Fig. 3 is the computation model main body figure of typical bridge section II

Bridge floor traffic safety wind speed schematic diagram when Fig. 4 is microbus zero load, limiting vehicle speed 100km/h under different wind angles.

Bridge floor traffic safety wind speed schematic diagram when Fig. 5 is microbus zero load, limiting vehicle speed 80km/h under different wind angles.

Bridge floor traffic safety wind speed schematic diagram when Fig. 6 is microbus zero load, limiting vehicle speed 60km/h under different wind angles.

Fig. 7 is the schematic diagram that is related to of incoming flow wind direction and reduction coefficient.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail, be convenient to be well understood to the present invention, but they do not form restriction to the present invention.

As shown in Figure 1, bridge spanning the sea wind barrier method for designing of the present invention is mainly height and these two parameters of ventilative rate of design wind barrier, determines that these two parameters of wind barrier are to be combined and determined by wind tunnel test and Numerical Wind Tunnel.

Adopt wind tunnel test that bridge spanning the sea model is fixed in wind-tunnel, set up have, bridge floor wind speed field model during calm barrier, simulation bridge floor environment, analyzes bridge floor wind speed field.Adopt on computers Numerical Wind Tunnel to set up to have simultaneously, bridge floor wind speed field Three-dimension Numerical Model during calm barrier, analyze bridge floor wind speed field, the analog result of wind tunnel test and Numerical Wind Tunnel is compared, result comparatively approaches the principal element that explanation has both considered to affect wind environment, and each bridge section of explanation bridge spanning the sea is in comparatively identical environment.The different bridge floor wind environments that different angles incoming flow wind causes, by the rule of testing acquisition, are used in Three-dimensional simulation

During simulation bridge floor environment, consider the impact of various factors, in bridge floor wind speed field model, various vehicles are set on different road surfaces, different load-carryings, the parameter at different bridge types place, by each parameter combination, then constantly change height and the ventilative rate of the wind barrier of simulating in bridge floor wind speed field model, bridge floor equivalent wind speed and wind speed reduction coefficient while calculating vehicle in the model under different parameters by bridge floor wind speed field model, record height and the ventilative rate of in corresponding bridge floor wind speed field model, simulating wind barrier simultaneously, the equivalent wind speed calculating is compared with the traffic safety wind speed of typical vehicle with wind speed reduction coefficient.Until a certain equivalent wind speed and wind speed reduction coefficient are within the scope of driving survival wind speed, at this parameter Imitating, having the bridge floor wind speed field model of wind barrier is safe in corresponding to actual conditions, the height of wind barrier and height and the ventilative rate of the wind barrier that ventilative rate is required design now simulated, height and the ventilative rate of the wind barrier finally obtaining according to simulation are designed qualified wind barrier.

Concrete steps, implementation method are as described below:

The first step: determine that according to bridge feature typical bridge section sets up wind tunnel test and Numerical Wind Tunnel model, analyze bridge floor wind speed field, and analyze the bridge floor wind speed field of different size wind barrier.The operating mode of setting up model comprises the calm barrier of typical bridge floor and wind barrier is set.Therefore the typical bridge section I of, determining and typical bridge section II are respectively as shown in Figure 2 and Figure 3.The height of wind barrier has been selected two kinds, and 3m, 4m are high.The air partition of every kind of height has again three kinds of ventilative rates, i.e. 50%, 60%, 70% 3 kind of situation.Like this, the specification of wind barrier has six kinds.

Second step: determine typical vehicle, analyze the safety traffic wind speed of different automobile types under different wind angles.Numerical Wind Tunnel and the model in wind tunnel of the typical bridge section establishing according to the first step, analyze and test equivalent wind speed and the wind speed reduction coefficient of bridge floor, and compare with the traffic safety wind speed of typical vehicle.

Use for reference the vehicular traffic status investigation result on the main highway of China arterial highway, and according to the physical dimension of vehicle, quality and aerodynamic characteristic feature etc., determine that representational vehicle is divided into following four kinds: car, microbus (or minivan), transportation medium truck (or middle bus), van container trailer, representative vehicle is the star in Toyota Crown car, Chang'an, graceful board lorry and Baker trailer.According to the aerodynamic coefficient of typical vehicle and bridge floor parameter, analyze, obtain between different wind directions and vehicle body after the inclination under angle and sideslip critical wind velocity and lateral deviation critical wind velocity, therefrom select minimum critical wind velocity, can obtain bridge floor traffic safety wind speed, in Table 1.

Take microbus as example, and shown in Fig. 4-6 is car vehicle safe driving wind speed in the different speed limit situations under different wind angles when unloaded.As seen from the figure, minimum traffic safety wind speed at 60 degree to 80 degree, be not that our incoming flow wind of often thinking is during perpendicular to bridge floor, therefore, bridge floor arranges the impact that wind barrier will be considered incoming flow wind angle, and the checking coefficient that wind barrier is set can not adopt incoming flow wind perpendicular to bridge floor time, it is relatively dangerous designing like this wind barrier.

The bridge spanning the sea bridge floor traffic safety wind speed (m/s) of table 1 under different pavement states

The typical bridge segment model establishing, adopts Numerical Wind Tunnel to set up the three-dimensional finite element model of typical bridge section I and II, according to equivalent wind speed computing formula:

or can calculate the equivalent wind speed that obtains bridge floor, further obtain wind speed reduction coefficient, V in formula (z) and V (z _i) be respectively bridge floor height z and z _ithe side direction incoming flow wind speed at place; Z _ealtitude range for automobile; N is along automobile height measuring point quantity.

In the situation that only having guardrail, when incoming flow wind speed is 30m/s, the equivalent wind speed in typical bridge section I and each track of II and reduction coefficient are as shown in table 2 and table 3.

Equivalent wind speed and the reduction coefficient of typical bridge section I when table 2 only has guardrail

?	1m	2m	3m	4m	4.5m	5m	Equivalent wind speed	Reduction coefficient
										1 track	28.5	37	38	38	38.2	38	35.8976	1.1966
2 tracks	28	36	37.5	37.5	37.5	37.5	35.2629	1.1754
									3 tracks	27.5	35	37	37	37	37	34.6530	1.1551
4 tracks	20.5	36	37.5	37.5	37.8	37.5	34.1343	1.1378
									5 tracks	23.5	36	37.5	38	38.4	38	34.7556	1.1585
6 tracks	25	35	36.5	37	37.3	37	34.1464	1.1382

Table 3 only has equivalent wind speed and the reduction coefficient of the typical bridge section II of guardrail

?	1m	2m	3m	4m	4.5m	5m	Equivalent wind speed	Reduction coefficient
										1 track	5	3.5	26	43	45	43	28.1849	0.9395
2 tracks	6	5	9	35	46.3	44	23.2802	0.7760
									3 tracks	7.5	7.5	7	16	36.8	43	15.5964	0.5199
4 tracks	10	7.5	8	22.5	32.1	39	16.6113	0.5537
									5 tracks	13	10	12.5	28	36.4	40	20.3946	0.6798
6 tracks	15.5	10	21.5	33	36.9	40	23.9086	0.7970

In wind tunnel test, in the situation that typical bridge section II only has guardrail, when incoming flow wind speed is 6.8m/s, equivalent wind speed and the reduction coefficient in each track are as shown in table 4.

Table 4 only has equivalent wind speed and the reduction coefficient of the standard paragraphs of guardrail

?	5m	4.5m	4m	3m	2m	1m	Equivalent wind speed	Reduction coefficient
										1 track	7.1934	7.3170	7.1885	7.7434	6.2113	3.3276	6.4646	0.9507
2 tracks	7.0088	6.5796	6.8725	6.8851	4.6024	2.4365	5.6451	0.8302
									3 tracks	7.3184	7.3307	7.1620	7.1736	5.3745	4.9770	6.3819	0.9385
4 tracks	7.0508	7.1303	6.6642	5.7931	5.7848	4.7114	5.9452	0.8743
									5 tracks	6.8133	6.617	6.3443	6.1459	4.8776	4.7679	5.7046	0.8389

6 tracks

7.0084

6.923

6.7569

6.8857

5.4022

5.9125

6.3452

0.9331

The reduction coefficient of three-dimensional numerical value simulation of wind is more close with the reduction coefficient of wind tunnel test, the analog result that three-dimensional numerical value wind field is described is rational, the principal element that affects wind field is all taken into account, with it, analyzing bridge floor wind field is relatively safe substantially.

That according to wind tunnel test and Numerical Wind Tunnel, determines only has the bridge floor wind speed reduction coefficient in guardrail situation, analyzed the safety traffic wind speed of each typical vehicle, be converted into local weather station wind scale, according to the annual strong wind number of days in bridge site place, in the situation that speed limit is 60km/h, microbus type will be less than 300 days for 1 year can not go up bridge, middle Light-duty Vehicle type will be less than 180 days for 1 year can not go up bridge, container-trailer type will have about 180 days can not go up bridge for 1 year, and car type is less than 90 days for 1 year can not go up bridge.If wind barrier is not set, will greatly reduce the utilization rate of this bridge.Therefore, must wind barrier be set at bridge spanning the sea bridge floor.

The 3rd step: when analyzing bridge floor different size wind barrier being set, i.e. the wind speed reduction coefficient of each typical bridge section during the wind barrier of differing heights and different ventilative rate.Such as the checking coefficient in more typical bridge section I and II each track when wind angle 90 is spent in Numerical Wind Tunnel analysis only having guardrail, the high 50% ventilative rate of 3m is set, the high 70% ventilative rate of 3m and the high 50% ventilative rate of 4m, or the checking coefficient in more typical bridge section II each track when wind angle 90 is spent in wind tunnel experiment only having guardrail, the high 50% ventilative rate of 3m is set, the high 60% ventilative rate of 3m, the high 70% ventilative rate of 3m and the high 50% ventilative rate of 4m.

The 4th step: calculate when wind barrier is set, the bridge floor equivalent wind speed of bridge floor wind speed field model and wind speed reduction coefficient are compared with the traffic safety wind speed of typical vehicle, can judgement arrange this specification wind barrier and meet each typical vehicle safety traffic.

According to second step analysis, when incoming flow wind direction becomes 70 to spend with bridge floor angle, the survival wind speed of Vehicle Driving Cycle is minimum substantially, therefore, first selecting wind angle is 70 as least favorable wind angle, to analyze the vehicle safe driving wind scale under the wind barrier of all size while spending, to determine the wind barrier of engineering demands.Then, then checking computations are while arranging the wind barrier selected, the vehicle safe driving wind scale under other wind directions.Finally, comprehensive above analysis, determines the specification that wind barrier is set at typical bridge section II.

When incoming flow wind direction becomes 70 to spend with bridge floor angle, each typical vehicle as shown in table 5 without air partition bridge floor survival wind speed.

Survival wind speed under table 5 different automobile types and different speed limit

(a) operating mode one: wind barrier height 3m, ventilative rate 50%.

By analyzing, in conjunction with the numerical simulation of bridge floor wind field and the result of wind tunnel test, under this operating mode, wind speed reduction coefficient is 0.6077, and the safety traffic wind speed of each typical vehicle under the different speed limits in bridge floor place is as shown in table 6.

Survival wind speed under table 6 different automobile types and speed limit (the incoming flow wind speed at bridge floor place)

(b) operating mode two: wind barrier height 3m, ventilative rate 60%

This operating mode wind speed reduction coefficient is 0.6159, and the survival wind speed under the different speed limits of typical car is as shown in table 7.

Survival wind speed under table 7 different automobile types and speed limit (the incoming flow wind speed at bridge floor place)

(c) operating mode three: wind barrier height 3m, ventilative rate 70%

By analyzing, in conjunction with the numerical simulation of bridge floor wind field and the result of wind tunnel test, the wind speed reduction coefficient under this operating mode is 0.6701, and the survival wind speed of each typical vehicle under the different speed limits of bridge floor At The Height is as shown in table 8 below.

Survival wind speed under table 8 different automobile types and speed limit (the incoming flow wind speed at bridge floor place)

(d) operating mode four: wind barrier height 4m, ventilative rate 50%

In conjunction with the numerical simulation of bridge floor wind field and the result of wind tunnel test, the wind speed reduction coefficient under this operating mode is 0.4675, and the survival wind speed of each typical vehicle under the different speed limits of bridge floor At The Height is as shown in table 9 below.

Survival wind speed under table 9 different automobile types and speed limit (the incoming flow wind speed at bridge floor place)

(e) operating mode five: wind barrier height 4m, ventilative rate 60%

Analyze the numerical simulation of bridge floor wind field and the result of wind tunnel test, the wind speed reduction coefficient under this operating mode is 0.5029, and the survival wind speed of each typical vehicle under the different speed limits of bridge floor At The Height is as shown in table 10 below.

Survival wind speed under table 10 different automobile types and speed limit (the incoming flow wind speed at bridge floor place)

(f) operating mode six: wind barrier height 4m, ventilative rate 70%

By analyzing the numerical simulation of bridge floor wind field and the result of wind tunnel test, the wind speed reduction coefficient that obtains this operating mode is 0.5807, and the survival wind speed of each typical vehicle under the different speed limits of bridge floor At The Height is as shown in table 11 below.

Survival wind speed under table 11 different automobile types and speed limit (the incoming flow wind speed at bridge floor place)

For this bridge section, according to above analysis, can obtain the survival wind speed of various typical vehicle being provided with that 3m is high by 50%, under 60% and 70% ventilative rate wind barrier and the operating mode such as 4m is high by 50%, 60% and 70% ventilative rate wind barrier.Consider the situation that other typical bridge sections of bridge security and bridge spanning the sea arrange wind barrier, suggestion here arranges the wind barrier of the high 50% ventilative rate of 3m in this bridge section, so comparatively economical and have a good vehicle pass-through effect.Therefore, under other different wind direction angles, analyze the operating mode that vehicle safe driving wind speed only considers to arrange the high 50% ventilative rate wind barrier of 3m, it is current whether checking meets vehicle safety when this specification wind barrier is set.If analyzed after the wind angle of all incoming flow wind, can meet vehicle safe driving, determine at typical bridge section II the high 50% ventilative rate wind barrier of 3m is set.Other typical bridge piecewise analysis processes are identical.

For different incoming flow wind directions, the wind speed reduction coefficient difference of the wind barrier of same size is set, the typical bridge section II of take is example, the high 50% wind speed reduction coefficient of ventilative rate wind barrier of 3m and the relation of incoming flow wind angle is set as shown in Figure 7.As can be seen from the figure, wind speed reduction coefficient and incoming flow wind direction have very large relation.Therefore, likely cause when 90 spend, the wind speed reduction coefficient that wind barrier is set can, so that the safety traffic wind speed of vehicle reaches engine request, still can not meet the requirement of vehicle safe driving when other incoming flow wind angles.

Bridge floor arranges the impact that wind barrier will be considered incoming flow wind angle, and the checking coefficient that wind barrier is set can not adopt incoming flow wind perpendicular to bridge floor time, it is relatively dangerous designing like this wind barrier.Under different incoming flow wind, consider these two factors of wind speed reduction coefficient and vehicle safe driving wind speed simultaneously.In order to compare with the result that incoming flow wind direction is 90 degree, adopt the concept of the wind direction influence coefficient of the present invention's proposition.

When identical wind barrier is set, wind direction influence coefficient is defined as: the bridge floor of the safety traffic when bridge floor place incoming flow wind speed and 90 of the safety traffic of other incoming flow wind direction vehicle is spent goes out the ratio of incoming flow wind speed

${\mathrm{<figure-callout\; id="90"\; label="S"\; filenames="HDA0000417341850000022.png,HDA0000417341850000041.png"\; state="\{\{state\}\}">S</figure-callout>}}_{90}=\frac{{\mathrm{<figure-callout\; id="90"\; label="V\; d\; V"\; filenames="HDA0000417341850000022.png,HDA0000417341850000041.png"\; state="\{\{state\}\}">V</figure-callout>}}_d}{V_{}}$

In formula, S ₉₀for make the wind direction influence coefficient of reference, V with incoming flow wind direction 90 degree _dthe bridge floor place incoming flow wind speed that any incoming flow wind direction is provided with vehicle safe driving after wind barrier, V ₉₀that incoming flow wind direction is the bridge floor place incoming flow wind speed of the 90 degree vehicle safe driving that has identical wind barrier.Here consider that vehicle is the least favorable situation on unloaded and wet road surface.

Wind direction influence coefficient under table 12 different automobile types and speed limit under different incoming flow wind directions

Table 12 explanation, when wind direction influence coefficient is greater than 1.0, represents that according to incoming flow wind direction be the safety traffic requirement that the 90 wind barriers that arrange while spending can meet other incoming flow wind direction vehicles; But when wind direction influence coefficient is less than 1.0, represent to take that incoming flow wind direction can not meet the safety traffic needs of other incoming flow wind direction vehicles as the wind barrier of 90 degree analyses designs.Therefore, when wind barrier is set, consider the impact of incoming flow wind direction, the joint effect of namely considering vehicle safe driving wind speed under incoming flow wind direction and wind speed reduction coefficient is safety relatively to the design of air partition.

The 5th step: if can judge that according to the 4th step it is safe having the bridge floor of wind barrier wind speed field model, the height of wind barrier and height and the ventilative rate of the wind barrier that ventilative rate is required design now simulated; Otherwise repeat the first step to the four steps.

The 6th step: the height of the wind barrier obtaining according to simulation and ventilative rate are designed qualified wind barrier.

Rely on the Three-dimensional simulation of typical bridge section and the PRELIMINARY RESULTS of wind tunnel test, according to the traffic safety requirement of bridge spanning the sea highway bridge floor, can tentatively determine wind barrier height and the ventilative rate of bridge spanning the sea highway bridge.Concrete wind barrier structure form mainly consists of air partition bar and air partition column two parts.Air partition bar and air partition column all adopt Q235B steel, and its technical standard should meet the requirement of GB/T1591-2008 < < low-alloy high-tensile structural steel > >.

Claims (4)

1. a bridge spanning the sea wind barrier method for designing, is characterized in that, comprises the following steps:

(1), by wind tunnel test and Numerical Wind Tunnel set up respectively, bridge floor wind speed field model during calm barrier, analyze bridge floor wind speed field, the two mutually combines, verifies, compares, and constantly changes height and the ventilative rate of the wind barrier of simulating in bridge floor wind speed field model simultaneously;

(2) bridge floor equivalent wind speed and wind speed reduction coefficient, while calculating vehicle by bridge floor wind speed field model, and compare with the traffic safety wind speed of typical vehicle;

(3), in bridge floor equivalent wind speed and wind speed reduction coefficient, when calculating vehicle by bridge floor wind speed field model, record height and the ventilative rate of in bridge floor wind speed field model, simulating wind barrier;

(4), by the vehicle calculating, by the bridge floor equivalent wind speed of bridge floor wind speed field model, compare with the traffic safety wind speed of typical vehicle with wind speed reduction coefficient, judge to simulate have whether safety of the bridge floor wind speed field model of wind barrier;

(5) if judge in step (4), simulation has the bridge floor wind speed field model of wind barrier is safe, the height of wind barrier and height and the ventilative rate of the wind barrier that ventilative rate is required design now simulated; Otherwise repeating step (1)-(4);

(6) height of the wind barrier, obtaining according to simulation and ventilative rate are designed qualified wind barrier.

2. bridge spanning the sea wind barrier method for designing according to claim 1, is characterized in that: the parameter combining in the bridge floor wind speed field model of setting up by wind tunnel test and Numerical Wind Tunnel in described step (1) comprises different automobile types, different road surface, different load-carrying, different bridge type and their combination in any.

3. bridge spanning the sea wind barrier method for designing according to claim 1, is characterized in that: the equivalent wind speed computing formula in described step (2) is: or $V_{\mathrm{eq}}={\left[\frac{1}{Z_e}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\left(V\left(z_i\right)\right)}^2{z}_i\right]}^{1/2}$

Wherein: V (z) and V (z _i) be respectively bridge floor height z and z _ithe side direction incoming flow wind speed at place; Z _ealtitude range for automobile; N is along automobile height measuring point quantity.

4. bridge spanning the sea wind barrier method for designing according to claim 1, is characterized in that: the equivalent wind speed that in described step (2), wind speed reduction coefficient is bridge floor and the ratio of actual side direction incoming flow wind speed.

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