JP4076185B2 - How to design an extended floor slab - Google Patents

Description

  The present invention relates to a method for designing an extended floor slab, and more particularly to a method for designing an extended floor slab configured to have strength as a concrete paving slab.

  Conventionally, in order to absorb expansion and contraction due to temperature changes of the bridge girder, an expansion device is provided between the bridge girder and the abutment. Since the telescopic device is located in the gap between the bridge girder and the abutment, a shock is generated when the vehicle passes to cause discomfort to the occupant, and deterioration of the environment due to generation of noise and vibration becomes a problem.

In order to solve this problem, the applicant of the present invention arranges a bottom plate made of precast concrete on the earthwork section side, receives one end of the bottom plate on the abutment, and on the bottom plate from the bridge side to the earthwork section side. A method has been proposed in which an extended floor slab made of precast concrete is disposed and an expansion device is provided on the earthwork part side (see, for example, Patent Document 1).
JP 2004-084280 A

  In the invention described in Patent Document 1, by extending the bridge floor slab and moving the expansion / contraction device to the earthwork part side, the impact from the passing vehicle can be alleviated and the generation of vibration and noise can be reduced. The structure of the extended floor slab is constructed with the strength of the bridge floor slab based on the idea of extending the bridge floor slab. The bridge deck is built between abutments and piers and supported locally at several points, so the concrete thickness and reinforcement are designed to withstand it. Despite the presence of a bottom slab and ground on the lower surface of the extension slab and supporting the extension slab, the extension slab is designed with the strength of a bridge slab, so it has more strength than necessary. This increases the cost.

  Therefore, when designing an extended floor slab, a technical problem to be solved in order to reduce costs while providing the necessary strength arises, and the present invention aims to solve this problem.

The present invention has been proposed in order to achieve the above object, the invention according to claim 1, extends from the end of the bridge side on the bottom plate which is arranged on the earthwork portion side to earthwork portion An extended floor slab provided with a telescopic device on the earthwork part side, the extended floor slab is made of a concrete plate, the extended floor slab is constructed with strength as a concrete paving slab, and a plurality of concrete plates are connected When the extended floor slab is constructed with the strength as a concrete paving slab, the supporting force on the lower surface of the extended floor slab is considered as a spring, and when the concrete slab is deformed by a wheel load, In addition to calculating the generated stress, the warp restraining force generated in the concrete plate due to the temperature difference between the front and back surfaces of the concrete plate due to temperature change is calculated, and the stress generated by the wheel load and the temperature change By combining the warp binding more generated calculated composite stress sigma _C, after conversion to the cross-sectional force M from the synthetic stress sigma _C, it provides a method of designing the extension deck to calculate the stress of the concrete and rebar To do.

The load point of the wheel load is a center portion of the concrete plate, an outermost extension portion of the concrete plate, and a joint vicinity portion of adjacent concrete plates, and the stress degree is calculated at each portion . Provides an extended floor slab design method.

The composite stress σ _C is calculated by adding the stress generated by the wheel load when the concrete plate temperature rises and the warp restraint stress generated by the temperature change, and the stress generated by the wheel load when the temperature drops. A method for designing an extended floor slab according to claim 1 to be calculated is provided.

The method for designing an extended floor slab according to claim 1, wherein the cross-sectional force M is converted from the composite stress σ _C using the cross-section coefficient Z and is calculated with the entire cross-section effective .

  According to the above configuration, the structure of the extended floor slab is designed with the strength as a concrete paving slab, the dimensions such as the width and thickness of each precast concrete slab constituting the extended floor slab, and the reinforcing bar The bar arrangement, such as type and number of installations, is configured with the same design as the concrete paving slab.

  In the present invention, since the extended floor slab is designed with the strength as a concrete paving slab with the above configuration, the member cross-section can be configured thinly compared to the design as a conventional bridge floor slab, and the reinforcement is also arranged. Since it can be simplified, it is possible to reduce the cost while providing the required strength when designing the extended floor slab.

  Hereinafter, a method for designing an extended floor slab according to the present invention will be described with reference to preferred embodiments. In designing the extended floor slab, the purpose of reducing the cost while providing the required strength was realized by designing the structure of the extended floor slab with the strength as a concrete paving slab.

  FIG. 1 is a cross-sectional view of an extended floor slab constructed in the vicinity of a bridge portion. A bridge girder 11 forming a bridge portion 10 is placed on a bridge 13 via a support 12, and the bridge floor slab is placed on the bridge girder 11. 14 is arranged. The earthwork section 15 places a bottom plate 17 on the compacted embankment 16, extends one end portion of the bottom plate 17 to the upper surface of the abutment 13, and fixes it with an anchor bolt 19 via a buffer rubber 18. The bottom plate 17 is provided with grout injection holes 20 in various places. After adjusting the height of the bottom plate 17 with a jack or the like, a grout material is injected from the grout injection hole 20 and filled into the gap with the embankment 16.

  An extended floor slab 21 is disposed on the bottom slab 17, and one end of the extended floor slab 21 on the bridge portion 10 side is placed on the upper surface of the bridge floor slab 14 via a buffer rubber 22. Then, the cast-in-place concrete 24 is placed on the protruding portion of the hinge structure (menase hinge in this embodiment) 23 embedded in one end of the extended floor slab 21 so that the extended floor slab 21 and the bridge floor slab 14 are connected. Connected together. The other end of the extended floor slab 21 is connected to one end of a detachable floor slab 27 via a cotter joint 26. The detachable floor slab 27 is provided with a telescopic device 28, and the other end of the detachable floor slab 27 is fixed to the bottom slab 17 with an anchor bolt 29. A pavement surface 30 is continuously constructed from the bridge portion 10 on the upper surface of the extended floor slab 21.

The bottom plate 17 and the extended floor slab 21 are each formed by connecting a plurality of precast reinforced concrete plates, and the contact surface between the bottom plate 17 and the extended floor slab 21 is formed extremely smoothly. When the bridge girder 11 expands and contracts due to the temperature change on the bridge part 10 side, the extended floor slab 21 joined to the bridge floor slab 14 is pushed and pulled by the bridge floor slab 14 and slides on the upper surface of the bottom slab 17, The expansion / contraction is absorbed by the expansion device 28.

  Next, a method for designing the extended floor slab 21 will be described. FIG. 2 is a flowchart of a method for designing an extended floor slab. First, as a preparatory work, the design conditions are arranged, and the length of the extended floor slab is determined according to the kick-up amount.

  Regarding the examination of the bottom plate, first, the thickness of the bottom plate and the basic bar arrangement are determined by examining the plate as a stepping plate or a plate for the purpose of forming a smooth surface. As a structural member, we will consider the case of a wall railing vehicle collision and the cotter arrangement interval. As a study at the time of construction such as when precast concrete plate is suspended, it will be examined at the time of lift-up. Then, consider anchors for fixing the bottom plate.

  Regarding the examination of the extended floor slab and the removable floor slab, in the present invention, the basic reinforcement is determined by considering the design of the extended floor slab as a concrete paving slab instead of a bridge floor slab. As a structural member, we will examine the stress in the gap section, the wall railing, and the cotter arrangement interval. Then, as in the case of the bottom plate, the construction is examined at the time of hanging the precast concrete plate. As a study on the anchor bolts on the fixed side of the removable floor slab, the anchor bolts and inserts will be examined.

Regarding the examination of the bridge joint, it is assumed that a menase hinge is used as an example of the hinge structure, and it is necessary to examine the play, the examination of the menase, and the examination at the time of earthquake.
§1 Design conditions (1) Design method Design based on the allowable stress design method of RC analysis in accordance with the road bridge specifications.
(2) Materials used Table 1 shows examples of materials used.

(3) Various physical constants Table 2 shows an example of various physical constants of reinforced concrete.

The Young's modulus of the reinforcing bar is E _s = 2.0 × 10 ⁵ (N / mm ² )
The Young's modulus of the cotter type fitting (H-type hardware) is _Eco = 1.7 × 10 ⁵ (N / mm ² )
(4) Load conditions
4.1 Live load Live load shall be B live load (T-25). 3A shows the bridge axis direction in the left-right direction in the drawing, and FIG. 3B shows the direction perpendicular to the bridge axis in the left-right direction in the drawing.

4.2 Dead load Table 3 shows examples of dead load values for reinforced concrete γ _c and asphalt pavement γ _a .

(5) Allowable stress level An example of the allowable stress level of each material used is shown in Table 4.

  An example of an additional factor of the allowable stress degree is shown in Table 5.

(6) Preconditions The extended floor slab shall be designed based on the following preconditions according to the intentions of the client and various conditions of the bridge.
"Extended floor length"
The distance that the telescopic device installed at the end of the bridge has moved to the earthwork side.
"Kick-up amount"
The amount of jumping (lifting amount) due to the rotation of the bridge end caused by deflection due to live load or the like at the bridge end. In the present invention, the maximum value is considered as +0.002 rad.
"Bridge travel"
The amount of movement of the bridge is determined by the amount of movement at the bridge temperature expansion and contraction and seismic motion level 1 o'clock, and the expansion / contraction device is determined from the largest value among the values.

  Table 6 shows an example of the amount of expansion and contraction of the bridge.

Based on the above values, the expansion / contraction device installed on the extended floor slab is an expansion / contraction device corresponding to the expansion / contraction amount of ± 100.6 mm in the bridge axis direction.
"Seismic force"
During an earthquake, the bridge and the extension slab will move differently. In order that the extended floor slab does not impose an unreasonable burden on the bridge, the menase hinge joining the bridge and the extended floor slab is designed to yield at seismic vibration level 2. Table 7 shows an example of the force generated when a bridge earthquake occurs.

(7) Structure details
7.1 Shape and member dimensions The plate thickness of precast concrete plates satisfies the following conditions.

(1) Minimum total thickness 160mm or more
(2) Necessary plate thickness for cotter joint specifications 200 mm or more Based on the above conditions, the plate thickness of the precast concrete plate should be 200 mm or more. The plate thickness of the extended floor slab is t = 200mm, and the plate thickness of the bottom slab is determined by the design of the tread plate.

7.2 Minimum Reinforcing Bar A steel material with an adhesive strength of 0.15% or more of its cross-sectional area is placed on the member.

    The cross-sectional area of the axial tension main reinforcing bar arranged in the reinforced concrete structure is determined by the following equation.

A _st ≧ 0.005b _w · d
However, the thickness of the direction in which the shearing force acts is small, and the member on which the oblique tension reinforcing bar cannot be arranged is determined by the following equation.

A _st ≧ 0.01b _w · d
Here, A _st : cross-sectional area of the axial tension main reinforcing bar (mm ² )
b _w : digit web thickness (mm)
d: Effective thickness (mm)
7.3 Minimum fog Table 8 shows an example of the minimum fog of precast members and cast-in-place concrete.

7.4 Opening of reinforcing bars The opening of reinforcing bars shall satisfy all the following conditions.

(1) 40 mm or more (20 mm or more for precast materials)
(2) More than 4/3 times the maximum size of coarse aggregate (20mm)
(3) More than 1.5 times the diameter of the reinforcing bar
When using a lap joint to 7.5 rebar joint tensile reinforcement shall be superimposed over lap joint length L _a calculating and more than 20 times the diameter of the reinforcing bars by the following equation. The lap joint is reinforced with two or more reinforcing bars arranged at right angles to the joint. In addition, when using a mechanical joint for the tensile reinforcement, the strength of the joint is determined in consideration of the type, diameter, stress state, joint position, etc. of the reinforcement.

L _a = (σ _sa · φ) / (4τ _0a )
Here, L _a: lap joint length to be calculated from the bond stress degree (mm)
σ _sa : Allowable tensile stress of reinforcing steel (N / mm ² )
φ: Rebar diameter (mm)
τ _0a : Allowable bond stress level of concrete (N / mm ² )
When joints are concentrated on the same cross section, “Reinforcing Bar Joint Guidelines (Concrete Library No. 49)” (Japan Society of Civil Engineers) Refer to Article 9 (2).

7.6 Arrangement of main reinforcing bars The main reinforcing bars shall be reinforcing bars with a diameter of 13 mm or more.

    The main reinforcing bars are arranged in two stages or less.

7.7 Arrangement of core rebars Reinforcing bars should be arranged so that cracks that may occur due to drying shrinkage of concrete, temperature gradient, stress concentration, etc. are not harmful.

    The core rebars should have a diameter of 13mm or more and be arranged at intervals of 300mm or less.

In the vicinity of the joint, a rebar is placed against the tensile stress caused by the temperature difference between the old and new concrete, drying shrinkage, etc.
§2 Examination of extended floor slabs and removable floor slabs As mentioned above, bridge floor slabs are installed between abutments and piers and are supported at several local points, whereas Since the bottom plate and embankment (ground) exist on the lower surface of the plate to support the extended floor slab, the structure of the extended floor slab, such as concrete thickness and reinforcement, is considered as a concrete paving plate. As a result, the member cross-section can be made thin, and the member cross-sectional dimension does not change, so that it can be made inexpensive.

The concrete pavement plate has a stress generated by the wheel load and a warp restraint stress generated by the temperature change. The combined stress σ _c is calculated by combining (adding) both stresses and converted to the sectional force M. Later, the degree of stress of the concrete structure (force per unit area acting on each element such as concrete and rebar when cross-sectional force acts) will be examined.

  The stress generated by the wheel load is the stress generated in the concrete due to the external load (the wheel load of automobiles, aircrafts, etc.). As shown in FIG. 4, when the wheel load is loaded on the concrete plate, the concrete plate As for the stress generated inside, a compressive force is generated on the upper surface and a tensile force is generated on the lower surface.

  On the other hand, the stress generated by temperature change is mainly the warpage restraint stress because the warpage restraint stress is superior to other stresses. This is the stress generated inside the concrete slab, because of the temperature difference between the slab and the weight of the concrete slab.

  As shown in FIG. 5, when the outside air temperature decreases, the temperature of the upper surface of the concrete plate decreases and the upper surface tends to contract. At this time, the stress generated in the concrete plate generates a compressive force on the upper surface and a tensile force on the lower surface.

According to the pavement design guideline, the bearing capacity coefficient of the roadbed necessary for designing the concrete plate is set to 2 MPa / cm for the flat plate loading test value K ₃₀ for the loading plate having a diameter of 30 cm. In the present invention, since the bottom surface of the extended floor slab has a bottom slab, it is calculated assuming that a necessary roadbed bearing force coefficient is secured. In addition, since the flat plate loading test value K ₇₅ for a loading plate having a diameter of 75 cm is required for the design of the concrete plate, when the flat plate loading test value K ₃₀ is converted to K ₇₅ , the following values are obtained.

In the present invention, the supporting force of the roadbed on the lower surface of the pavement is considered as a spring, and the stress generated in the concrete plate when the concrete plate is deformed by a wheel load is calculated. The warp restraint stress generated in the concrete plate due to the temperature difference between the stress and the stress generated by the wheel load and the warp restraint stress generated by the temperature change is calculated to calculate the composite stress σ _c , After converting the stress σ _c to the cross-sectional force M, the degree of stress between the concrete and the reinforcing bar is examined.
(1) Calculation of stress level
1.1 Degree of stress due to wheel load The stress generated when a wheel load is loaded on the concrete plate is calculated using the Westerguard formula, and the loading point of the wheel load is the center of the concrete plate as shown in Fig. 6. The stress level is examined in each of the three parts (i), the outermost edge part (b) of the concrete plate, and the joint vicinity part (c) between adjacent concrete plates.

When central loading (A) and at the outermost edge loading (b) is calculated by the coefficient C, etc. determined relative stiffness radius r, the tire contact radius a, the impact wheel load P _i, the concrete joint shape. When the joint vicinity portion is loaded (C), the stress σ _e calculated by the formula when the outermost edge portion is loaded (B) is multiplied by the reduction coefficient α determined by the joint shape.

  “Rigidity radius r” is determined by the rigidity ratio of the concrete slab and the roadbed within the range of influence when the wheel load is loaded. Usually, the traffic load has multiple wheels but is converted to a single wheel (equivalent to an equivalent single wheel). The range of influence is modified to be close to the actual multiple wheels.

The “impact wheel load P _i ” is a rear wheel load that takes into account the impact when the vehicle passes.

  “Coefficient C” is a coefficient used when calculating the stress σe when the outermost edge is loaded. When there is no joint at the outermost edge of the concrete pavement, the value of 2.12 is used, and the joint is included. If this is the case, use a value of 1.59.

  The “reduction coefficient α” is a coefficient used when calculating the stress σco at the time of loading in the vicinity of the joint, and is determined by the strength and reliability of the joint. For cotter type joints used in extended floor slabs, use a value of 0.6.

(A) Stress generated when the central part is loaded The stress generated when the central part is loaded is examined using the following equation.

  here,

  Therefore,

(B) Generated stress when the outermost edge is loaded The generated stress when the outermost edge is loaded is examined using the following equation.

(C) Generated stress in the vicinity of the joint The load stress in the vicinity of the joint expresses the load transmission effect as a coefficient based on the free edge and is examined using the following formula.

1.2 Stress generated by warping restraint Stress due to warping restraint acts on the concrete plate due to the temperature difference between the upper and lower surfaces of the concrete plate. The joint vicinity is assumed to have a stress state close to the center of the plate when the concrete plate is rigidly connected, so the value is the same as the center of the plate.

  Here, the temperature difference θ ′ between the upper and lower surfaces of the concrete plate is 15 ° C. This means that in areas where the temperature difference is small (area where the daily amplitude of the temperature hardly exceeds 14 ° C), the temperature difference between the upper and lower surfaces of the concrete plate with a plate thickness of 200mm cannot exceed 15 ° C. This is because it is clearly stated in the construction guidelines.

Warping restraint coefficient C _w is a coefficient determined by the sign of joint spacing and temperature difference.

1.2.1 Temperature rise (a) Warp restraint stress at the center of the plate The warp restraint stress at the center of the plate is examined using the following equation.

(B) Warpage restraint stress at the outermost edge The warpage restraint stress at the outermost edge is examined using the following equation.

(C) Warpage restraint stress in the vicinity of the joint The warpage restraint stress in the vicinity of the joint is examined using the following equation.

1.2.2 When the temperature drops (b) Warp restraint stress at the center of the plate The warp restraint stress at the center of the plate is examined using the following equation.

(B) Warpage restraint stress at the outermost edge The warpage restraint stress at the outermost edge is examined using the following equation.

(C) Warpage restraint stress in the vicinity of the joint The warpage restraint stress in the vicinity of the joint is examined using the following equation.

1.3 Composite stress σ _c
Calculate the composite stress level at the bottom of the concrete slab. When the temperature of the concrete slab rises, the combined stress is calculated by adding the stress generated by the wheel load and the warp restraint stress generated by the temperature change. When the temperature of the concrete slab drops, only the stress generated by the wheel load is calculated. Calculate. Table 9 shows an example of a list of combined stresses generated at the plate center portion, the joint vicinity, and the edge portion when the temperature rises and when the temperature falls.

For example, at the center of the plate when the temperature rises, the stress due to the wheel load (live load stress) is σ _i = 3.291 N / mm ^{2 as} shown in Equation ² , and the warpage restraint stress is as shown in Equation 5. Since σ _ti = 2.080 N / mm ² , the resultant stress σ _c is 5.371 N / mm ² . Also, when the temperature drops, the calculation is based only on the stress generated by the wheel load. For example, the stress due to the wheel load (active load stress) at the edge is σ _e = 5.491 N / mm ^{2 as shown} in Equation ³ . Therefore, the composite stress σ _c is 5.491 N / mm ² .
(2) Calculation of cross-sectional force The cross-sectional force M is converted using the cross-sectional modulus Z from the resultant stress σ _c determined as described above. Here, the calculation is performed with the entire cross section effective so that the calculation is performed on the safety side. FIG. 7 is a stress distribution diagram when the entire cross section is valid.

  The cross section of the concrete plate shall be 200mm thick and unit width 1000mm. Therefore, the section modulus Z is expressed by the following equation.

The cross-sectional force M _{i +} at the center of the plate when the temperature rises, the cross-sectional force M _{co +} near the joint, and the cross-sectional force M _{e + at the} edge are examined by the following equations.

Member forces M _i-in plate central portion during temperature lowering, member forces the joint vicinity M _co-, member forces M _e- are at the edges to consider the following equation.

  The axial force N is a compressive force and tensile force generated when the bridge is temperature-expanded, and is generated when the extended floor slab is pushed and pulled, and is a value calculated by the following equation. Note that the friction coefficient μ is 1.0 in consideration of safety. When the bridge is extended, the axial force acts in the compression direction, which is advantageous in the calculation of the cross section. For safety reasons, the axial force N is not considered when compressing.

  As shown in Fig. 8, the basic reinforcement of the concrete plate is to place 10 steel bars of D1 and a diameter of 19mm per meter at 60mm and 140mm from the top surface of the 200mm thick concrete plate. .

  Table 10 and FIG. 9 to FIG. 14 show examples of examination results of the degree of stress generated at the plate center, the vicinity of the joint, and the edge for each of the temperature rise and temperature drop.

  “Compression-side concrete compression stress σc”: compression stress generated in compression-side concrete when a cross-sectional force is applied.

“Tensile-side rebar tensile stress σ _s ”: Tensile stress generated in the tensile-side rebar when a cross-sectional force is applied.

“Compression side rebar compression stress σ _{s ′} ”: compression stress generated in the compression side rebar when a cross-sectional force is applied.

“Allowable compressive stress σ _ca ”: a limit value of concrete compressive stress in the allowable stress design method determined by the concrete strength.

“Allowable tensile stress σ _sa ”: The limit value of the reinforcing bar tensile stress in the allowable stress design method determined by the reinforcing bar material.

  “Neutral axis X”: the position of the center of gravity in the H section.

  “Young's modulus ratio n”: Young's modulus represents the stiffness of the material, and Young's modulus ratio n is the ratio between the Young's modulus of concrete and the Young's modulus of rebar.

  In the reinforce bar description column, as described above, it is described that 10 bars of steel type D1 and a diameter of 19 mm are arranged per 1 m at positions 60 mm and 140 mm from the upper surface of a 200 mm thick concrete plate.

As a result, the permissible stress level could be satisfied with the basic reinforcement.
(3) Checking the minimum amount of reinforcing bars A _s (D19) = 286.5mm ²
3.1 All sections are checked at m pitch.

A _s1 = A _s (D19) x 20 = 286.5 x 20 = 5730mm ²
Because 0.15% or more of the member cross-sectional area is required,
A _smin1 = 200mm × 1000mm × 0.0015 = 300mm ² <A _s1 ⇒ OK
3.2 Axial main reinforcing bars Check at m pitch.

A _s2 = A _s (D19) × 10 = 286.5 × 10 = 2865mm ²
A _smin2 = 0.01 ・ b _w・ d = 0.01 × 1000mm × 160 = 1600mm ² <A _s2 ⇒ OK

  Each numerical value shown in this example is an example, and other numerical values can be used by modifying the numerical value without departing from the spirit of the present invention. It goes without saying.

Sectional view of the extended floor slab constructed near the bridge. The flowchart of the design method of an extended floor slab. It is a figure explaining a live load, (a) shows a bridge axis direction in the left-right direction in a figure, (b) The figure which shows a bridge axis perpendicular direction in the left-right direction in a figure. Explanatory drawing which shows the stress which generate | occur | produces by wheel load. Explanatory drawing which shows the stress which generate | occur | produces with a temperature change. Explanatory drawing which shows the location which loads a wheel load on a concrete plate. Stress distribution diagram when all sections are valid. Explanatory drawing showing the basic reinforcement of concrete plate. Explanatory drawing which shows the examination result of the generated stress degree in the plate center part at the time of temperature rise. Explanatory drawing which shows the examination result of the generated stress degree in the joint vicinity at the time of temperature rise. Explanatory drawing which shows the examination result of the generated stress degree in the edge at the time of a temperature rise. Explanatory drawing which shows the examination result of the generated stress degree in the plate center part at the time of temperature fall. Explanatory drawing which shows the examination result of the generated stress degree in the joint vicinity at the time of temperature fall. Explanatory drawing which shows the examination result of the generated stress degree in the edge part at the time of temperature fall.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Bridge part 11 Bridge girder 12 Support 13 Abutment 14 Bridge floor slab 15 Earthwork part 16 Filling 17 Bottom slab 18 Buffer rubber 19 Anchor bolt 20 Grout injection hole 21 Extension floor slab 22 Buffer rubber 23 Menase hinge (hinge structure)
24 Cast-in-place concrete 26 Cotter-type joints 27 Detachable floor slab 28 Telescopic device 29 Anchor bolt 30 Pavement surface

Claims (4)

An extended floor slab that is extended from the end on the bridge side to the earthwork part on the bottom slab arranged on the earthwork part side, and provided with a telescopic device on the earthwork part side. The extended floor slab is composed of strength as a concrete paving slab, and is formed by connecting a plurality of concrete slabs,
When the extended floor slab is constructed with the strength as a concrete paving slab, the supporting force of the lower surface of the extended floor slab is considered as a spring, and the stress generated in the concrete slab when the concrete slab is deformed by a wheel load. As well as calculating
Calculate the warping restraint force generated in the concrete plate due to the temperature difference between the front and back surfaces of the concrete plate due to temperature change,
The combined stress σ _C is calculated by synthesizing the stress generated by the wheel load and the warp restraining force generated by the temperature change, and after converting the combined stress σ _C to the sectional force M, the degree of stress between the concrete and the reinforcing bar An extended floor slab design method characterized by calculating 2. The extended floor according to claim 1, wherein the loading point of the wheel load is a central portion of the concrete plate, an outermost extension portion of the concrete plate, and a joint vicinity portion of adjacent concrete plates, and the stress level is calculated at each portion. How to design a plate. The composite stress σ _C is calculated by adding the stress generated by the wheel load when the concrete plate temperature rises and the warp restraint stress generated by the temperature change, and calculating the stress generated by the wheel load when the temperature drops. The method for designing an extended floor slab according to claim 1. The method for designing an extended floor slab according to claim 1, wherein the cross-sectional force M is converted from the composite stress σ _C using a cross-sectional modulus Z and is calculated with an effective total cross-section.

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