Prestressed hollow slab

Abstract

The application discloses a prestressed hollow slab, which comprises a hollow slab body, a hollow structure is formed on the hollow slab body, the hollow structure comprises two shear resistance end holes and a plurality of hollow through holes, the shear resistance end holes and the plurality of hollow through holes are distributed along the length direction of the cross section of the hollow slab body, the hollow through holes are located between the two shear resistance end holes, the maximum width of the cross section of the shear resistance end hole is smaller than the maximum width of the cross section of the hollow through hole, and the maximum height of the cross section of the shear resistance end hole is equal to the maximum height of the cross section of the hollow through hole. By optimizing the hole type on both sides into a narrow waist type, the net width of the side rib of the hollow slab is increased, the shear influence coefficient is not considered when the shear bearing capacity is calculated, and the shear capacity of the prestressed hollow slab is obviously improved.

Description

Technical Field

[0001] This invention relates to the technical field of hollow slabs, and particularly to the technical field of prestressed hollow slabs. Background Technology

[0002] A hollow slab is a flat plate with longitudinal internal holes along its entire span. Hollow slabs remove concrete near the neutral axis, which has little effect on the slab's bending resistance, thus significantly reducing the structure's self-weight. Compared to cast-in-place bridge decks or floor slabs, precast hollow slabs offer advantages such as lighter weight, no need for formwork, faster construction speed, reliable quality, and lower cost. Therefore, hollow slabs are widely used in precast bridges and buildings.

[0003] The existing prestressed hollow slabs generally have a cross-sectional width of 1200mm and a thickness of 150mm-500mm. The size of the through holes in the hollow slabs is basically the same. The applicant's research on the load-bearing capacity of prestressed hollow slabs found that when the thickness of the hollow slab is greater than 220mm, the shear bearing capacity gradually weakens to the bending bearing capacity, and the prestressed hollow slabs with a thickness greater than 220mm cannot meet the requirements for large span load-bearing. Summary of the Invention

[0004] The purpose of this invention is to solve the problems in the prior art by proposing a prestressed hollow slab that can solve the above problems.

[0005] To achieve the above objectives, the present invention proposes a prestressed hollow slab, comprising a hollow slab body, wherein a hollow structure is formed on the hollow slab body, the hollow structure comprising two shear-resistant end holes and a plurality of hollow through holes in the middle, the shear-resistant end holes and the plurality of hollow through holes being distributed along the length direction of the cross-section of the hollow slab body, the hollow through holes being located between the two shear-resistant end holes, and the minimum distance D1 between the shear-resistant end hole and its adjacent hollow through hole being greater than the minimum distance D2 between two adjacent hollow through holes.

[0006] Preferably, the maximum width of the shear-resistant end hole cross-section is less than the maximum width of the hollow through hole cross-section, and the maximum height of the shear-resistant end hole cross-section is equal to the maximum height of the hollow through hole cross-section.

[0007] Preferably, the cross-section of the shear-resistant end hole includes a symmetrically arranged upper and lower circular arcs, which are connected by two vertical ribs with a distance of D4 between them.

[0008] Preferably, the hollow slab body has a stepped structure on its side, the stepped structure including grooves and protrusions, the protrusions having a vertical splicing surface, the distance D3 between the splicing surface and its adjacent vertical rib is greater than the minimum distance D1 between the shear-resistant end hole and its adjacent hollow through hole.

[0009] Preferably, the cross-section of the hollow through hole is circular.

[0010] Preferably, the device includes a top surface and a bottom surface, with the two ends of the top surface and the bottom surface connected by vertical side ribs, and the distance D5 between the two vertical side ribs is greater than the distance D4 between the two vertical rib sides.

[0011] Preferably, the width of the top surface is greater than the width of the bottom surface, and the vertical side ribs are connected to the bottom surface by a ramp.

[0012] As a preferred option, there are 2-4 options.

[0013] The beneficial effects of this invention are as follows: By optimizing the hole shape on both sides into a narrow waist shape, the clear width of the side ribs of the hollow slab is increased. When two slabs are spliced ​​together, a steel mesh is inserted into the joint and a reinforcing bar is set outside the joint, forming a rectangular hidden beam with a width greater than 200mm. It is no longer a narrow waist cross section. When calculating the shear bearing capacity, the shear force influence coefficient is not considered, which significantly improves the shear resistance of thicker prestressed hollow slabs.

[0014] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of Example 1;

[0016] Figure 2 This is a schematic diagram of the structure of Example 2;

[0017] Figure 3 This is a schematic diagram of the structure of Example 3;

[0018] Figure 4 This is a schematic diagram of the structure of Example 4;

[0019] Figure 5 This is a schematic diagram of the structure of Example 5;

[0020] Figure 6 This is a schematic diagram of the structure of Example 6;

[0021] Figure 7 This is a schematic diagram of the structure of Example 7;

[0022] Figure 8 This is a schematic diagram of the structure of Example 8;

[0023] Figure 9 This is a schematic diagram of the structure of Example 9;

[0024] Figure 10 This is a schematic diagram of the structure of Example 10;

[0025] Figure 11 This is a schematic diagram of the structure of Example 11;

[0026] Figure 12 This is a schematic diagram of the structure of Example 12;

[0027] Figure 13 This is a schematic diagram of the structure of Example 13;

[0028] Figure 14 This is a schematic diagram of the structure of Example 14;

[0029] Figure 15 This is an assembly diagram of Example 5;

[0030] Figure 16 This is a schematic diagram of the original hole structure in Example 5.

[0031] In the diagram: 1-Hollow slab body, 2-Shear-resistant end hole, 3-Hollow through hole, 4-Vertical rib. Detailed Implementation

[0032] Example 1:

[0033] A prestressed hollow slab includes a hollow slab body 1. The hollow slab body 1 has a hollow structure, which includes two shear-resistant end holes 2 and four hollow through holes 3. The shear-resistant end holes 2 and hollow through holes 3 are distributed along the length of the cross-section of the hollow slab body 1. The hollow through holes 3 are located between two shear-resistant end holes 2. The minimum distance D1 between a shear-resistant end hole 2 and its adjacent hollow through hole 3 is greater than the minimum distance D2 between two adjacent hollow through holes 3. The maximum width of the cross-section of the shear-resistant end hole 2 is less than the maximum width of the cross-section of the hollow through hole 3. The maximum height of the cross-section of the shear-resistant end hole 2 is equal to the maximum height of the cross-section of the hollow through hole 3. The cross-section of the shear-resistant end hole 2 includes... The hollow slab body 1 is provided with an upper and lower circular arc, which are connected by two vertical ribs 4. The distance between the two vertical ribs 4 is D4. The side of the hollow slab body 1 is provided with a stepped structure, which includes a groove and a protrusion. The protrusion is provided with a vertical splicing surface 6. The distance D3 between the splicing surface 6 and its adjacent vertical rib 4 is greater than the minimum distance D1 between the shear-resistant end hole 2 and its adjacent hollow through hole 3. The cross-section of the hollow through hole 3 is circular with a diameter of 155mm. The cross-sectional thickness of the hollow slab body 1 is 220mm. The cross-sectional height of the shear-resistant end hole 2 is 155mm. D1 = 40mm, D2 = 34mm, D3 = 104mm; D4 = 92mm.

[0034] Example 2 is basically the same as Example 1, except that: the cross-sectional thickness of the hollow plate body 1 is 250mm, there are three hollow through holes 3, the diameter of the circle is 180mm, the cross-sectional height of the shear-resistant end hole 2 is 180mm, D1=70mm, D2=44mm, D3=121mm.

[0035] Example 3 is basically the same as Example 1, except that: the cross-sectional thickness of the hollow plate body 1 is 265mm, there are three hollow through holes 3, the diameter of the circle is 185mm, the cross-sectional height of the shear-resistant end hole 2 is 185mm, D1=70mm, D2=39mm, D3=118mm.

[0036] Example 4:

[0037] A prestressed hollow slab includes a hollow slab body 1. The hollow slab body 1 has a hollow structure, which includes two shear-resistant end holes 2 and three hollow through holes 3. The shear-resistant end holes 2 and hollow through holes 3 are distributed along the length of the cross-section of the hollow slab body 1. The hollow through holes 3 are located between two shear-resistant end holes 2. The minimum distance D1 between a shear-resistant end hole 2 and its adjacent hollow through hole 3 is greater than the minimum distance D2 between two adjacent hollow through holes 3. The maximum width of the cross-section of the shear-resistant end hole 2 is less than the maximum width of the cross-section of the hollow through hole 3. The maximum height of the cross-section of the shear-resistant end hole 2 is equal to the maximum height of the cross-section of the hollow through hole 3. The cross-section of the shear-resistant end hole 2 includes a symmetrically arranged upper arc and a lower arc, which are connected by two vertical ribs 4. The distance between the two vertical ribs is D4. The hollow slab body 1 has a stepped structure on its side, which includes a groove and a protrusion. The protrusion has a vertical splicing surface 6. The distance D3 between the splicing surface 6 and its adjacent vertical rib 4 is greater than the minimum distance D1 between the shear-resistant end hole 2 and its adjacent hollow through hole 3. The hollow through hole 3 includes an arc-shaped top surface and a bottom surface. The two ends of the top surface and the bottom surface are connected by vertical side ribs. The distance D5 between two vertical side ribs is greater than the distance D4 between two vertical ribs 4. The width of the top surface is greater than the width of the bottom surface. The vertical side ribs and the bottom surface are connected by inclined surfaces. The maximum height of the cross-section of the hollow through hole 3 is 195mm. The cross-sectional thickness of the hollow slab body 1 is 265mm. The cross-sectional height of the shear-resistant end hole 2 is 195mm. D1 = 70mm, D2 = 42mm, D3 = 120mm; D4 = 92mm, D5 = 182mm.

[0038] Example 5:

[0039] Example 5 is basically the same as Example 4, except that: the maximum height of the cross-section of the hollow through hole 3 is 230mm, the thickness of the cross-section of the hollow plate body 1 is 300mm, the height of the cross-section of the shear-resistant end hole 2 is 230mm, D1 = 70mm, D2 = 45mm, D3 = 121mm; D4 = 92mm, D5 = 179mm.

[0040] Example 6:

[0041] A prestressed hollow slab includes a hollow slab body 1. The hollow slab body 1 has a hollow structure, which includes two shear-resistant end holes 2 and two hollow through holes 3. The shear-resistant end holes 2 and hollow through holes 3 are distributed along the length of the cross-section of the hollow slab body 1. The hollow through holes 3 are located between the two shear-resistant end holes 2. The minimum distance D1 between a shear-resistant end hole 2 and its adjacent hollow through hole 3 is greater than the minimum distance D2 between two adjacent hollow through holes 3. The maximum width of the cross-section of the shear-resistant end hole 2 is less than the maximum width of the cross-section of the hollow through hole 3. The maximum height of the cross-section of the shear-resistant end hole 2 is equal to the maximum height of the cross-section of the hollow through hole 3. The cross-section of the shear-resistant end hole 2 includes a symmetrically arranged upper arc and a lower arc, which are connected by two vertical ribs 4. The distance is D4. The side of the hollow slab body 1 is provided with a stepped structure, which includes a groove and a protrusion. The protrusion is provided with a vertical splicing surface 6. The distance D3 between the splicing surface 6 and its adjacent vertical rib 4 is greater than the minimum distance D1 between the shear-resistant end hole 2 and its adjacent hollow through hole 3. The hollow through hole 3 includes a top surface and a bottom surface. The two ends of the top surface and the bottom surface are connected by vertical side ribs. The distance D5 between the two vertical side ribs is greater than the distance D4 between the two vertical ribs 4. The top surface and the bottom surface are symmetrical arc surfaces. The maximum height of the cross section of the hollow through hole 3 is 252mm. The cross section thickness of the hollow slab body 1 is 320mm. The cross section height of the shear-resistant end hole 2 is 252mm. D1 = 85mm, D2 = 54mm, D3 = 144mm; D4 = 112mm, D5 = 229mm.

[0042] Example 7:

[0043] Example 7 is basically the same as Example 4, except that: the maximum height of the cross-section of the hollow through hole 3 is 248mm, the thickness of the cross-section of the hollow plate body 1 is 320mm, the height of the cross-section of the shear-resistant end hole 2 is 248mm, D1=75mm, D2=45mm, D3=116mm; D4=92mm, D5=179mm.

[0044] Example 8:

[0045] Example 8 is basically the same as Example 4, except that: there are two hollow through holes 3, the maximum height of the cross-section of the hollow through hole 3 is 280mm, the thickness of the cross-section of the hollow plate body 1 is 360mm, the height of the cross-section of the shear-resistant end hole 2 is 280mm, D1=90mm, D2=57mm, D3=150mm; D4=102mm, D5=226mm.

[0046] Example 9:

[0047] Example 9 is basically the same as Example 4, except that: the maximum height of the cross-section of the hollow through hole 3 is 270mm, the thickness of the cross-section of the hollow plate body 1 is 370mm, the height of the cross-section of the shear-resistant end hole 2 is 270mm, D1 = 100mm, D2 = 50mm, D3 = 119mm; D4 = 67mm, D5 = 174mm.

[0048] Example 10:

[0049] Example 10 is basically the same as Example 6, except that: the bottom surface of the hollow through hole 3 is provided with a plane, the maximum height of the cross-section of the hollow through hole 3 is 320mm, the cross-sectional thickness of the hollow plate body 1 is 400mm, the cross-sectional height of the shear-resistant end hole 2 is 320mm, D1=90mm, D2=55mm, D3=149mm; D4=102mm, D5=228mm.

[0050] Example 11:

[0051] Example 11 is basically the same as Example 4, except that: there are two hollow through holes 3, the maximum height of the cross-section of the hollow through hole 3 is 320mm, the thickness of the cross-section of the hollow plate body 1 is 400mm, the height of the cross-section of the shear-resistant end hole 2 is 320mm, D1=90mm, D2=55mm, D3=149mm; D4=102mm, D5=228mm.

[0052] Example 12:

[0053] Example 12 is basically the same as Example 4, except that: the maximum height of the cross-section of the hollow through hole 3 is 315mm, the thickness of the cross-section of the hollow plate body 1 is 400mm, the height of the cross-section of the shear-resistant end hole 2 is 315mm, D1 = 80mm, D2 = 50mm, D3 = 114mm; D4 = 92mm, D5 = 174mm.

[0054] Example 13:

[0055] Example 13 is basically the same as Example 4, except that: there are two hollow through holes 3, the maximum height of the cross-section of the hollow through hole 3 is 401mm, the thickness of the cross-section of the hollow plate body 1 is 500mm, the height of the cross-section of the shear-resistant end hole 2 is 401mm, D1=90mm, D2=70mm, D3=157mm; D4=102mm, D5=213mm.

[0056] Example 14:

[0057] Example 14 is basically the same as Example 4, except that: there are two hollow through holes 3, the maximum height of the cross-section of the hollow through hole 3 is 392mm, the thickness of the cross-section of the hollow plate body 1 is 500mm, the height of the cross-section of the shear end hole 2 is 392mm, D1=90mm, D2=68mm, D3=156mm; D4=102mm, D5=215mm.

[0058] The formula for calculating the shear strength of the original hole profile is:

[0059] [V]≤ψ0.7ftb w h0

[0060] ψ: Shear force reduction factor for thicknesses exceeding 200mm

[0061] The values ​​are as follows:

[0062]

[0063]

[0064] The values ​​of different cross-sectional heights are calculated using linear interpolation.

[0065] f t Design value of tensile strength of concrete;

[0066] b w Minimum net rib width of the cross section;

[0067] h0: Effective height of the cross section;

[0068] Formula for calculating the shear strength of the optimized hole profile:

[0069] [V]≤ψ*0.7ftb w(中间) h0d+0.7ftb w(两侧) h0d

[0070] b w(中间) : The net width of the middle rib of the hole type and

[0071] b w(两侧) The width of the net ribs on both sides of the hole-shaped cross section.

[0072] Taking Example 5 as an example, the original hole structure before the improvement in Example 5 is as follows: Figure 16 As shown.

[0073] The test results of the original hole type bearing capacity of Example 5 are shown in the table below.

[0074]

[0075] The load-bearing capacity test results of the improved embodiment 5 are shown in the table below.

[0076]

[0077] Calculations and comparisons revealed that modifying the hole widths on both sides significantly improved shear resistance and enabled it to adapt to the large-span bearing capacity of thick prestressed hollow slabs.

[0078] The reason for the improved shear capacity of the optimized hole section is that after the hole shape on both sides is optimized as shown in the figure above, the net width of the side ribs is increased, and the two plates are spliced ​​together. The steel mesh for grouting is inserted and the plate surface reinforcement is set outside the grouting, forming a rectangular hidden beam with a width of more than 200mm. It is no longer a narrow waist section. When calculating the shear capacity, the shear force influence coefficient is not considered, which significantly improves the shear capacity of the thicker prestressed hollow slab.

[0079] The comparison of shear bearing capacity between the original and optimized hole types calculated in Examples 1-14 is shown in the table below:

[0080]

[0081] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the scope of protection of the present invention.

Claims

1. A prestressed hollow slab, characterized in that: The system includes a hollow slab body (1), on which a hollow structure is formed. The hollow structure includes two shear-resistant end holes (2) and several hollow through holes (3). The shear-resistant end holes (2) and several hollow through holes (3) are distributed along the length of the cross-section of the hollow slab body (1). The hollow through holes (3) are located between the two shear-resistant end holes (2). The maximum width of the cross-section of the shear-resistant end hole (2) is less than the maximum width of the cross-section of the hollow through hole (3). The minimum distance D1 between the shear-resistant end hole (2) and its adjacent hollow through hole (3) is greater than the minimum distance D2 between two adjacent hollow through holes (3). The cross section includes a symmetrically arranged upper and lower circular arcs, which are connected by two vertical ribs (4). The distance between the two vertical ribs (4) is D4. The side of the hollow slab body (1) is provided with a stepped structure, which includes a groove and a protrusion. The protrusion is provided with a vertical splicing surface (6). The distance D3 between the splicing surface (6) and its adjacent vertical rib (4) is greater than the minimum distance D1 between the shear end hole (2) and its adjacent hollow through hole (3). The two hollow slab bodies (1) are spliced ​​together, and a grouting steel mesh is inserted in the slab joint. The grouting surface is provided with slab surface reinforcing bars to form a rectangular hidden beam with a width greater than 200mm.

2. The prestressed hollow slab as described in claim 1, characterized in that: The maximum height of the cross-section of the shear-resistant end hole (2) is equal to the maximum height of the cross-section of the hollow through hole (3).

3. The prestressed hollow slab as described in claim 1, characterized in that: The cross-section of the hollow through hole (3) is circular.

4. The prestressed hollow slab as described in claim 1, characterized in that: The hollow through hole (3) includes a top surface and a bottom surface. The two ends of the top surface and the bottom surface are connected by vertical side ribs. The distance D5 between the two vertical side ribs is greater than the distance D4 between the two vertical rib sides (4).

5. The prestressed hollow slab as described in claim 4, characterized in that: The top surface is wider than the bottom surface, and the vertical side ribs are connected to the bottom surface by a ramp.

6. The prestressed hollow slab as described in claim 1, characterized in that: The thickness of the cross-section of the hollow slab body (1) is 220mm~500mm.

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