Wind-resistant design method for extra-large extended balconies

Abstract

The present invention relates to the field of architectural design. In order to facilitate the wind-resistant design of super-large overhanging balconies, a wind-resistant design method for super-large overhanging balconies is provided, comprising: step 1, extracting a typical segment based on an architectural design scheme, wherein the typical segment is the smallest unit in which the building presents periodic changes; step 2, partitioning the balconies in the typical segment according to the stress conditions of the balconies; step 3, establishing a numerical model based on the typical segment and arranging monitoring points; step 4, setting numerical simulation experimental conditions and conducting tests under different wind direction angles to obtain the wind pressure moment of each monitoring point; step 5, extracting the extreme points in all wind pressure moments; step 6, judging whether the extreme value distribution of the wind pressure moment meets the requirements based on the inspection standard; if not, adjusting and optimizing the architectural design scheme, and repeating steps 2-6 until the extreme value distribution of the wind pressure moment meets the requirements. The above method is adopted to facilitate the wind-resistant design of super-large overhanging balconies.

Description

Technical Field

[0001] The invention relates to the field of architectural design, and in particular to a wind-resistant design method for an extra-large overhanging balcony. Background Art

[0002] Conventional balconies typically don't consider wind loads; instead, they only need to design the structure for a combination of dead and live loads. This is because traditional balconies experience low wind loads, and due to their short overhangs, the structural response to wind loads is smaller than that to dead and live loads, thus not providing a controlling effect. Therefore, using a combination of dead and live loads as the controlling load during structural design can ensure structural safety.

[0003] However, for oversized balconies (overhangs exceeding 2.5 meters, even 4-5 meters, and exceeding 20 square meters), the increased cantilever length and platform area increase the area affected by wind loads, making the impact of wind loads non-negligible. Furthermore, due to the increased size of the balcony, it has transformed from a building exterior appendage into an integral aerodynamic component. Therefore, targeted wind resistance design for oversized balconies becomes essential, and how to implement this wind resistance design is a pressing issue. Summary of the Invention

[0004] In order to facilitate the wind-resistant design of extra-large overhanging balconies, this application provides a wind-resistant design method for extra-large overhanging balconies.

[0005] The technical solution adopted by the present invention to solve the above problems is:

[0006] Wind-resistant design methods for extra-large overhanging balconies include:

[0007] Step 1: Extract typical segments based on the architectural design. The typical segment is the smallest unit of the building that exhibits periodic changes. In the architectural design, the dimensions of the balcony are length B and width d, the height between two adjacent balconies is h, the vertical overlap width between two adjacent balconies is b, and the distance between the balcony and the building corner is l.

[0008] Step 2: partition the balconies in the typical section according to the stress conditions of the balconies;

[0009] Step 3: Establish a numerical model based on the typical section and arrange monitoring points;

[0010] Step 4: Set the numerical simulation experimental conditions and conduct experiments under different wind direction angles to obtain the wind pressure at each monitoring point and calculate the wind pressure moment;

[0011] Step 5: Extract all the extreme points in the wind pressure moments. The extreme point is defined as the point with the largest wind pressure moment value among a total of 9 points in a circle around it. For the 8 monitoring points in a circle around the extreme point, if the difference between the wind pressure moment and the value of the extreme point is less than x%, they are also regarded as extreme points;

[0012] Step 6: Based on the inspection criteria, judge whether the distribution of the extreme values of the wind pressure moment meets the requirements. If not, adjust and optimize the building design plan, and repeat Steps 2 - 6 until the distribution of the extreme values of the wind pressure moment meets the requirements.

[0013] Further, Step 2 is specifically as follows:

[0014] The range of the length l1 at one end of the balcony close to the building corner is defined as Area I, the range of the overlapping area b of the projections of the upper and lower balconies is defined as Area III, and the remaining intermediate length range l2 is defined as Area II; each area is further divided into inner and outer parts, with a total of six areas: outer I, outer II, outer III, inner I, inner II, and inner III. Among them, l1 + l2 + b = B.

[0015] Further, in Step 2, the basis for the inner and outer zoning is: the outer 1 / 3d is the outer area, and the inner 2 / 3d is the inner area.

[0016] Further, in Step 2, if l2 is greater than l1, then take l1 = l; otherwise, take l1 = l2 = (B - b) / 2.

[0017] Further, in Step 3, the layout method of the monitoring points is: starting from the outermost edge of the balcony, arrange n rows of monitoring points at equal intervals along the width direction,

[0018] When l1 < l2, at least three columns of monitoring points are arranged in Area I, with at least one column centered and the left and right sides close to the area boundary lines; at least four columns of monitoring points are arranged in Area II, with at least two columns centered and the left and right sides close to the area boundary lines;

[0019] When l1 = l2, at least three columns of monitoring points are arranged in both Area II and Area I, with at least one column centered and the left and right sides close to the area boundary lines;

[0020] When b ≤ l2, at least three columns of monitoring points are arranged in Area III, with at least one column centered and the left and right sides close to the area boundary lines;

[0021] When b > 12, at least four columns of monitoring points are arranged in Area III, with at least two columns centered and the left and right sides close to the area boundary lines.

[0022] Further, in Step 3, the monitoring points in the centered arrangement are arranged at equal intervals.

[0023] Furthermore, the calculation method of the wind pressure moment in step 4 is as follows: a coordinate system is established with the point on the intersection line of the balcony and the building as the origin, and Pu i,j is the surface wind pressure at the monitoring point P(i, j), Pd i,j is the surface wind pressure at the monitoring point P(i, j), then the wind pressure moment MP is: MP i,j =P i,j ×j,P i,j =Pu i,j -Pd i,j .

[0024] Furthermore, in step 6, the inspection criteria are: the number of extreme points in the six partitions except the inner II zone does not exceed 1, more than k% of the extreme points are located in the inner zone, and more than k% of the extreme points in the inner zone are located in the inner II zone.

[0025] Furthermore, the method for adjusting and optimizing the architectural design scheme in step 6 includes:

[0026] When more than half of the extreme points fall in zone I, adjust l;

[0027] When more than half of the extreme points fall in zone III, adjust b;

[0028] When more than half of the extreme points fall in the outer zone, adjust d;

[0029] When the extreme point appears at the corner of the outer I or outer III zone, the balcony at that location will be changed to an arc shape.

[0030] Furthermore, in step 4, the incoming flow direction from the balcony directly opposite is 0°, and within the range of plus or minus 45°, a wind direction angle of every 15° is taken, for a total of 7 incoming flow direction conditions for numerical simulation.

[0031] Compared to existing technologies, this method offers the following advantages: Balconies are partitioned based on their load conditions, monitoring points are deployed within each partition, wind loads are evaluated by calculating the wind pressure moments at these monitoring points, and wind-resistant design optimization is performed based on the wind load evaluation results. This method utilizes a simple evaluation metric, consisting solely of the wind pressure moment, and a simple, single-line analysis logic, eliminating the need for multi-dimensional, multi-level analysis, resulting in higher analysis efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Flowchart of wind-resistant design method for extra-large extended balconies;

[0033] Figure 2 It is a typical segment schematic diagram;

[0034] Figure 3 Design stereograms for architectural sections;

[0035] Figure 4 Design elevations for building sections;

[0036] Figure 5 This is a schematic diagram of the balcony partition;

[0037] Figure 6 Schematic diagram of the numerical model;

[0038] Figure 7 Schematic diagram of measuring point arrangement;

[0039] Figure 8 It is the location map of the measuring points;

[0040] Figure 9 Schematic diagram for setting boundary conditions of numerical models;

[0041] Figure 10 Schematic diagram of the simulated working condition;

[0042] Figure 11 Schematic diagram of wind pressure moment extreme value distribution;

[0043] Figure 12 An example of the extreme value distribution of wind pressure moment to meet the inspection requirements. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] like Figure 1 As shown in the figure, the wind-resistant design method for extra-large overhanging balconies includes:

[0046] Step 1: Extract typical segments based on the architectural design plan. The typical segment is the smallest unit of the building that exhibits periodic changes.

[0047] The buildings with large overhanging platforms are basically high-rise and super high-rise residential buildings. These buildings have the same characteristics, that is, their appearance is almost unchanged and shows periodic changes. Because the most significant influence on the wind load of the platform is the flow state of the wind field above and below the platform, there is almost no mutual influence between multiple platforms. Therefore, the first step is to select a typical segment: intercept a part of its regular periodic changes and take a group as a typical segment, such as Figure 2 As shown, in order to show the periodic change pattern and facilitate parameterized annotation, the display diagram only captures two typical segments for illustration.

[0048] According to the air flow conditions of conventional building surfaces and cantilevered panels, the key dimensions of the structural design are parameterized. Since the corners of the building are the main places where airflow separates and forms vortices, the distance between the balcony and the corner of the building is defined as l. The upper and lower balconies constrain the movement of the airflow in the vertical direction, causing a large number of vortices to remain in this area. The energy cannot diffuse outward and will act on the balcony. The distance between the upper and lower balconies is defined as h. Taking the schematic diagram as an example, the distance between the upper and lower balconies of the same specification is 2h, while the distance between two adjacent balconies of different specifications is only h. The reduction in the balcony spacing will inevitably increase the wind load at the corresponding position, so it is necessary to focus on inspecting this part, and the vertical projection overlapping width is defined as b. At the same time, the size of the balcony itself is also an important influencing factor. The balcony length is defined as B, and the cantilever length (width) is defined as d. See for details. Figure 3 、 Figure 4 The sizes of the two staggered balconies can be the same, both length B and width d, or different, namely length B1 and width d1 and length B2 and width d2. This embodiment is described by taking the same sizes as an example.

[0049] Step 2: Divide the balconies in the typical section according to the stress conditions of the balconies.

[0050] Since the wind load on the balcony is affected by many factors such as its own geometric dimensions, the shape of the facade of the main structure to which it is attached, and interference from other balconies, and the scope and location of the influence of various factors are also different, the balcony can be divided into different influence zones accordingly. The wind will separate in front of the balcony to form a vortex and then attach to the structure, so that the outside is mainly controlled by the negative pressure of the separation vortex, while the inside is mainly affected by the impact and slip caused by the reattachment of the separation vortex. Therefore, the inside and outside have significantly different wind load characteristics and can be divided into outer and inner zones; in the overlapping area of ​​staggered balconies, the distance between the platforms becomes smaller, the movement space of the airflow after separation on the outside of the balcony is reduced, and the vertical constraint increases, which may cause more violent back and forth impacts between the upper and lower platforms and escape laterally; the airflow separates at the corner of the building to form a large number of vortices, and the side of the balcony close to the corner will be affected by them; the middle of the balcony is mainly affected by the wind load caused by the incoming flow from the balcony. Therefore, the balcony can be divided along the length direction:

[0051] The balcony's edge near the building's corner is defined as Zone I within a length of l1, and the overlapping area d of the balcony projections on both sides is defined as Zone III. The remaining center, l2 in length, is Zone II. Each zone is further divided into inner and outer zones, with the outer 1 / 3d being outer and the inner 2 / 3d being inner. Alternatively, the inner and outer divisions can be adjusted based on actual circumstances. Thus, there are six zones in total: outer I, outer II, outer III, inner I, inner II, and inner III. l1 + l2 + b = B, as shown in the following example: Figure 5As shown in the figure. The range of Zone I affected by the corner vortex is taken as the width equal to the distance from the balcony to the corner, that is, l1 = l; if l2 < l1, then l1 = l2 = (B - b) / 2, that is, the range of Zone II is not less than that of Zone I. This is because Zone I is affected by the diffusion of the separated vortex at the corner of the building main body, while Zone II is the main area directly impacted by the oncoming flow, and the wind load on Zone II has a greater impact on the overall wind load.

[0052] According to the relative position relationship of the balconies, the following two special cases may exist.

[0053] (1) If the balconies overlap completely vertically, then l2 = 0, and b = B - l1, that is, only Zone I and Zone III remain.

[0054] (2) If the balconies are completely offset vertically, then b = 0, that is, only Zone I and Zone II remain.

[0055] Step 3: Establish a numerical model based on the typical section and arrange monitoring points.

[0056] Use various 3D modeling software to create a geometric model, export the geometric information of the model, and import it into ICEM or Meshing to establish a numerical model. Perform structured grid division on the numerical model and densify the grid around the building.

[0057] When establishing the model for numerical calculation analysis, it is sufficient to include three typical sections. The building main body extends upwards and downwards by no less than 4h in length, so as to provide vertical development space for the flow field. Designate the middle group as the test section, as Figure 6 shown. All calculations are carried out on this test section.

[0058] Both the upper and lower surfaces of the balcony are subject to wind load. Therefore, monitoring points are arranged on the upper and lower surfaces of the platform, and the upper and lower points correspond to each other. The outermost monitoring points should be arranged at the outermost edge positions.

[0059] As Figure 7 shown, in this embodiment, 6 points are evenly distributed at intervals of 1 / 5d in width. Since the innermost point is very close to the outer wall and the effect of the wind load is not significant, the innermost point is ignored, and only the outer five points are left. Multiple rows of measuring points can also be set according to the actual situation.

[0060] When l1 < l2, three columns of measuring points are arranged in Zone I, with the left and right sides close to the regional boundary lines and one column arranged in the middle; four columns of measuring points are arranged in Zone II, with the left and right sides close to the regional boundary lines and two columns arranged equidistantly in the middle;

[0061] When b ≤ l2, three columns of measuring points are arranged in Zone III, with the left and right sides close to the regional boundary lines and one column arranged in the middle;

[0062] When b>12, four rows of measuring points are arranged in Zone III, with the left and right sides close to the zone boundaries and two rows arranged in the center;

[0063] When l1=l2, zone II is arranged in three columns like zone I.

[0064] If the length of each partition is long, several more columns of measuring points can be set in the middle of each area according to the actual situation to improve accuracy.

[0065] In order to distinguish, locate and confirm the relative position relationship of each measuring point, two coordinate axes, i and j, are defined along the length and width directions respectively. The coordinates represent the sequence relationship, such as Figure 8 shown.

[0066] Step 4: Set the numerical simulation experimental conditions and conduct experiments under different wind direction angles to obtain the wind pressure at each monitoring point and calculate the wind pressure moment.

[0067] Numerical simulation was performed using computational fluid dynamics simulation software ANSYS Fluent. The turbulence model was selected as LES large eddy simulation. Figure 6 In the proposed model, the boundary conditions of the flow domain are symmetrical boundaries, the velocity inlet is the inlet, and the pressure outlet is the outlet. Since the surface boundary layer wind speed is low near the ground, the wind load on the balcony of the lower floor is small, while the wind speed at the upper floor is high, and the wind speed and turbulence intensity have a small change trend. Therefore, the inlet velocity is taken as a constant value, and the turbulence intensity at the corresponding height of the balcony is selected as the turbulence characteristic of the incoming flow according to the turbulence intensity profile specified in the building structure load code, such as Figure 9 shown.

[0068] Because the flow field around the balcony will be significantly different under different impact angles, the wind load will vary greatly. Figure 10 As shown in the figure, the numerical simulation was performed with the incoming flow direction from the balcony directly opposite as 0°, and a wind direction angle of 15° was selected within a range of ±45°, for a total of seven incoming flow direction conditions. After numerical simulation, wind pressure time history data was obtained at each measuring point.

[0069] Since the force arm in the outer area is larger and instantaneous strong loads may cause sudden damage, pulsating wind pressure is used at the measuring points in the outer area and average wind pressure is used at the measuring points in the inner area.

[0070] Since balconies are mostly plate structures with thickness much smaller than length and width, the loads on the upper and lower surfaces act together on one component. Therefore, it is only necessary to superimpose the loads on the upper and lower surfaces as a single overall wind load, without discussing the wind load effects of the upper and lower surfaces separately. i,j is the wind pressure on the upper surface, Pd i,j is the wind pressure on the lower surface, and the wind pressures at corresponding positions on the upper and lower surfaces are superimposed, P i,j =Pui,j -Pd i,j (j=4, 5 are pulsation values, j=1 to 3 are average values)

[0071] Since the monitoring points are evenly distributed along the width direction, there is no need to calculate the actual position of each point by complex statistics. Its coordinates along the j direction can be used instead of its arm as the moment coefficient. The wind pressure moment MP of each point can be obtained by multiplying the wind pressure and moment coefficient at each point: MP i,j =P i,j ×j.

[0072] After calculation, the overall wind pressure moment distribution of the balcony at different wind direction angles can be obtained.

[0073] Step 5: Extract the extreme points of all wind pressure moments. The extreme point is defined as the point with the largest wind pressure moment value among a total of 9 points in a circle around it. The wind pressure moments of the 8 monitoring points in a circle around the extreme point whose difference with the extreme point value is less than x% are also regarded as extreme points. In this embodiment, x is 10, and it can also be taken according to actual needs.

[0074] Step 6: Based on the inspection standard, determine whether the distribution of wind pressure moment extreme values ​​meets the requirements. If not, adjust and optimize the building design plan, and repeat steps 2-6 until the distribution of wind pressure moment extreme values ​​meets the requirements.

[0075] Mark the extreme points of wind pressure moment extracted in step 5 on the measurement point distribution map, as shown in the figure below: Figure 11 As shown, the white dots are the extracted wind pressure moment extreme points. The wind load on the balcony is evaluated based on the distribution of wind pressure moment extreme values ​​to test the aerodynamic performance of the balcony. The test standards are as follows: the number of extreme points in the six sub-areas except for the inner II area does not exceed 1; more than k% of the extreme points are located in the inner area, and more than k% of the extreme points in the inner area are located in the inner II area. In this embodiment, k is 60. An example of the wind pressure moment extreme value distribution that meets the test requirements is shown below. Figure 12 shown.

[0076] If the extreme value distribution of wind pressure moment does not meet the inspection standard, the corresponding structural parameters of the balcony shall be adjusted and optimized according to the following optimization method.

[0077] Optimization Method 1: If more than half of the extreme points fall in Zone I, this indicates that the airflow in Zones II and III is relatively smooth, while the airflow in Zone I is highly turbulent and the flow field is intense. Therefore, l can be adjusted, that is, the distance between the balcony and the building corner can be changed.

[0078] Optimization method 2: When more than half of the extreme points fall in zone III, it indicates that a large number of separated vortices appear in the airflow between the upper and lower balconies and oscillate back and forth between the platforms, causing severe loads. In this case, b can be adjusted to change the relative staggered position between the upper and lower balconies, thereby reducing the vortices and quickly attenuating and dissipating them.

[0079] Optimization method 3: When more than half of the extreme points fall in the outer area, it means that the airflow separates in front of the balcony and forms a violent vortex. At this time, d can be adjusted to control the vortex separation condition.

[0080] Optimization method 4: If it appears at the corner of outer I or outer III zone ( Figure 12 If the balcony is in the lower left or lower right corner), you can consider changing the local structure and changing the balcony to an arc shape.

[0081] The adjusted and optimized building will be re-tested and optimized according to steps 2-6. When the test results meet the test standards, the wind-resistant design is completed.

Claims

1. The wind-resistant design method for super-large extended balconies is characterized by: Including: Step 1: Extract typical segments based on the architectural design plan. The typical segment is the smallest unit where the building shows periodic changes. In the architectural design plan: the balcony has a length of B, a width of d, the height between adjacent balconies is h, the vertically projected overlapping width between adjacent balconies is b, and the distance from the balcony to the building corner is l. Step 2: Divide the balconies in the typical segment according to the force conditions of the balconies. Step 3: Establish a numerical model based on the typical segment and arrange monitoring points. Step 4: Set the numerical simulation experiment conditions and conduct experiments under different wind direction angles to obtain the wind pressure at each monitoring point and calculate the wind pressure moment. Step 5: Extract the extreme points among all the wind pressure moments. The extreme point is defined as the point with the largest wind pressure moment value among a total of 9 points in its surrounding circle. For the 8 monitoring points around the extreme point where the difference between the wind pressure moment and the value of this extreme point is less than x%, they are also regarded as extreme points. Step 6: Judge whether the distribution of the extreme values of the wind pressure moment meets the requirements based on the inspection criteria. If not, adjust and optimize the architectural design plan, and repeat Steps 2 - 6 until the distribution of the extreme values of the wind pressure moment meets the requirements.

2. The wind-resistant design method for a super-large overhanging balcony according to claim 1 is characterized in that: The specific content of Step 2 is as follows: The range within the length l1 at the end of the balcony close to the building corner is defined as Zone I, the range within the overlapping area b of the projections of the upper and lower balconies is defined as Zone III, and the remaining intermediate position with a length range of l2 is Zone II. Each zone is further divided into inner and outer parts, resulting in a total of six zones: outer I, outer II, outer III, inner I, inner II, and inner III. Here, l1 + l2 + b = B.

3. The wind-resistant design method for a super-large overhanging balcony according to claim 2 is characterized in that: In Step 2, the basis for the inner and outer division is: the outer 1 / 3d is the outer zone, and the inner 2 / 3d is the inner zone.

4. The wind-resistant design method for a super-large overhanging balcony according to claim 2 is characterized in that: In Step 2, if l2 is greater than l1, then take l1 = l; otherwise, take l1 = l2 = (B - b) / 2.

5. The wind-resistant design method for a super-large overhanging balcony according to claim 2 is characterized in that: In Step 3, the arrangement method of the monitoring points is: starting from the outermost edge of the balcony, arrange n rows of monitoring points at equal intervals along the width direction. When l1 < l2, at least three columns of monitoring points are arranged in Zone I, with the left and right sides closely adjacent to the area boundary lines, and at least one column is arranged in the middle; at least four columns of monitoring points are arranged in Zone II, with the left and right sides closely adjacent to the area boundary lines, and at least two columns are arranged in the middle. When l1 = l2, at least three columns of monitoring points are arranged in both Zone II and Zone I, with the left and right sides closely adjacent to the area boundary lines, and at least one column is arranged in the middle. When b ≤ l2, at least three columns of monitoring points are arranged in Zone III, with the left and right sides closely adjacent to the area boundary lines, and at least one column is arranged in the middle. When b > l2, at least four columns of monitoring points are arranged in Zone III, with the left and right sides closely adjacent to the area boundary lines, and at least two columns are arranged in the middle.

6. The wind-resistant design method for a super-large overhanging balcony according to claim 5 is characterized in that: In Step 3, the monitoring points arranged in the middle of each column are arranged at equal intervals.

7. The wind-resistant design method for a super-large overhanging balcony according to claim 6 is characterized in that: The calculation method of the wind pressure moment in step 4 is as follows: establish a coordinate system with the point on the intersection line of the balcony and the building as the origin, and set Pu i,j is the surface wind pressure at the monitoring point P(i, j), Pd i,j is the surface wind pressure at the monitoring point P(i, j), then the wind pressure moment MP is: MP i,j =P i,j ×j,P i,j =Pu i,j -Pd i,j .

8. The wind-resistant design method for a super-large overhanging balcony according to claim 2 is characterized in that: In Step 6, the inspection criteria are: the number of extreme points in the other regions except the inner II region in the six zones does not exceed 1, more than k% of the extreme points are located in the inner region, and more than k% of the extreme points in the inner region are located in the inner II region.

9. The wind-resistant design method for a super-large overhanging balcony according to claim 8 is characterized in that: The method for adjusting and optimizing the architectural design plan in Step 6 includes: When more than half of the extreme points fall in Zone I, adjust l. When more than half of the extreme points fall in Zone III, adjust b. When more than half of the extreme points fall in the outer region, adjust d. When the extreme point appears at the corner of the outer I or outer III zone, the balcony at that location will be changed to an arc shape.

10. The wind-resistant design method for a super-large overhanging balcony according to any one of claims 1 to 9, characterized in that: In step 4, the incoming flow direction from the balcony directly opposite is 0°, and the numerical simulation is performed with a wind direction angle of 15° within a range of plus or minus 45°, for a total of 7 incoming flow direction conditions.

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