CN105677962A - Sliding plate design optimization method - Google Patents

Abstract

The invention provides a sliding plate design optimization method. The sliding plate design optimization method comprises the following steps that (A) preparation is performed, specifically parameters are obtained, sensitivity analysis is performed and base bed coefficients are actually measured; (B) the sliding plate size is preliminarily planned, specifically sliding plate concrete strength, sliding plate thickness, the distance between adjacent anchorage beams, the specifications of the anchorage beams and the maximum allowable deformation of a sliding plate are selected according to the design requirements; (C) a beam grillage model of the sliding plate is established; (D) base stress checking calculation and maximum deformation checking calculation are performed; (E) sliding plate reinforcement calculation is performed to obtain sliding plate longitudinal beam reinforcement specifications and sliding plate transverse beam reinforcement specifications. The sliding plate design optimization method applies a beam grillage method to sliding plate design for jacking construction for the first time, the internal forces of anchorage beams and cast-in-place slabs are calculated by adopting the beam grillage method, the shortcomings of the sliding plate designed by relying on experiences can be overcome according to existing standard reinforcement, and a novel sliding plate design method is provided. The whole sliding plate design optimization method is simple in process, convenient to practice and convenient to popularize and use.

Description

A kind of sled design optimization method

Technical field

The present invention relates to technical field of bridge construction, be specifically related to a kind of sled design optimization method.

Background technology

Jacked frame bridge is more and more wider because not needing the advantage that close traffic, cost are low, area occupied is little to wear under highway to apply in crossings on different level engineering. For providing work place to prefabricated and jacked frame bridge, working pit and slide plate temporary structure need to be set). Slide plate, as working pit base plate, is again the slideway in jacking, becomes one of vitals in bridge construction.

At present, jacked frame bridge design is all relatively conservative is substantially based on experience), it is impossible to carry out targeted design according to geological conditions, frame bridge scale, execution conditions. In Practical Project, slide plate is generally adopted cast-in-place integral slab, and arranges anchor beam in vertical jacking direction to increase slide plate stability against sliding, has obvious orthotropy plates in construction feature.

Summary of the invention

A kind of method that present invention aim at providing sled design to optimize, concrete technical scheme is as follows:

A kind of method that sled design optimizes, comprises the following steps:

A, preparation process, specifically include the acquisition of parameter, sensitivity analysis and actual measurement bedding value, described sensitivity analysis is specifically: obtain, according to sensitivity computing formula, the key parameter that sled design optimizes, and the percentage ratio that affects according to each parameter determines most sensitive parameter; Described actual measurement bedding value is specifically: obtain bedding value value and allowable bearing capacity of foundation soil value according to relevant regulations and experience;

B, just intend slide plate size, specifically: select the maximum allowable deflection of the distance between slide plate concrete strength, the thickness of slide plate, adjacent anchor beam, the specification of anchor beam and slide plate according to designing requirement;

C, set up the space beam gird method of slide plate, specifically: the size according to the size of grillage model Design Theory slide plate longeron and virtual crossbeam, set support conditions according to bedding value, beam lattice unit size, calculate and obtain maximum deformation quantity, the design maximum moment of slide plate longeron and the design maximum moment of minimal design moment and slide plate crossbeam and the minimal design moment that slide plate is allowed;

The checking computations of D, base stress and maximum deformation quantity checking computations, specifically: obtain bearing reaction according to calculating, maximum base stress computing formula is utilized to obtain maximum base stress value, if maximum base stress value is less than or equal to allowable bearing capacity of foundation soil value, then ground need not be processed, otherwise need ground is processed;

Obtain maximum vertical deflection according to calculating, if the maximum deformation quantity that maximum vertical deflection is allowed less than or equal to slide plate, then described step B just intends slide plate Sizes, otherwise unreasonable; If slide plate Sizes, carry out next step; If the off size reason of slide plate, then return step B after changing the value of most sensitive parameter;

E, slide plate arrangement of reinforcement calculate, specifically: obtain, by calculating, slide plate longeron arrangement of reinforcement specification and the slide plate longeron arrangement of reinforcement specification meeting ultimate limit states requirement.

In above technical scheme preferably, in step A, the acquisition of parameter includes the following parameter obtaining slide plate crossbeam or longeron:

Compressive strength of concrete, concrete axial compressive strength, concrete axial tensile strength and ultimate compressive strain of concrete;

Steel Bar Tensile Strength design load, reinforcing bar elastic modelling quantity, reinforcing bar comprcssive strength design load and stirrup tensile strength design load;

Distance between moment-curvature relationship, shearing force design value, adjacent stirrup, square-section or trapezoid cross section, factor alpha₁, factor beta₁, compressive region flange width and the edge of a wing, compressive region height.

In above technical scheme preferably, in described step A, sensitivity analysis is specifically:

Set sensitivity calculating formula as expression formula 1):

$S_j=\frac{\underset{1}{\overset{m}{\Σ}}{\mathrm{\ΔM}}_i^2/\underset{1}{\overset{m}{\Σ}}{M}_i^2}{|{\mathrm{\Δx}}_j/x_j|}---1),$

In formula, x_jFor jth design parameter, Δ x_jFor parameter x_jKnots modification; M_iFor force value in controlling sections before parameter change, Δ M_iFor parameter x_jValue changes Δ x_jRear controlling sections internal force knots modification; M is for controlling number of parameters, S_jRepresenting the sensitivity of jth parameter, j is the number of parameters participating in sensitivity analysis;

Each parameter affect percentages formula 2) as follows:

$S_j^{\′}=S_j/\underset{1}{\overset{N}{\Σ}}{S}_i\×100\%---2),$

In formula, N is affecting parameters number;

The key parameter obtaining sled design is the thickness of slab of slide plate, the thickness of anchor beam, slide plate modulus of elasticity of concrete and elastic bearing coefficient, and the thickness of its middle slide plate is most sensitive parameter.

In above technical scheme preferably, in described step B: slide plate concrete strength is C30; The thickness of slide plate is 20-30mm; The maximum allowable deflection of slide plate is 5mm; Distance between adjacent anchor beam is 2-3m; The specification of anchor beam: anchor beam height is 50-80cm, anchor beam width is 30-50cm.

In above technical scheme preferably, described step C central sill lattice law theory is specifically: taking vertical jacking direction band anchor beam is beam lattice longitudinal bar member, and slide plate beam lattice divide and follow following factor:

Factor 1: beam lattice longitudinal bar member self cross section bending resistance the moment of inertia sum is equal to global sections bending resistance the moment of inertia;

Factor 2: for ensureing load transmission, transverse bar member spacing is less than longitudinal beam rib spacing;

Factor 3: beam ensures orthogonal in length and breadth, and crossbeam spacing is considered as the impact of slide plate leading edge oblique angles.

In above technical scheme preferably, maximum base stress computing formula such as expression formula 3 in described step D):

f_a=Fs/A_soil3),

Wherein: f_aFor maximum base stress; Fs is that space beam gird method calculates gained maximal support counter-force; A_soilFor beam lattice cell node correspondence ground contact area.

In above technical scheme preferably, described slide plate longeron or calculation of beam detailed process are as follows:

E1, flexure arrangement of reinforcement calculate, and comprise the following steps:

E11, relative limit depth of compressive zone ξ_bCalculate, particular by expression formula 4) calculate relative limit depth of compressive zone ξ_bValue, ξ_b=β₁/[1+f_y/(E_s×ε_cu)] 4), wherein: f_yFor Steel Bar Tensile Strength design load, E_sFor reinforcing bar elastic modelling quantity, ε_cuFor ultimate compressive strain of concrete;

E12, the edge of a wing are positioned at the T-shaped by flanging or I-shaped cross-section flexural member depth of compressive zone or Component in Single Rectangular Section or the edge of a wing is positioned at the T section flexural member depth of compressive zone of tight side and calculates, specifically: by expression formula 5) calculating obtains flexural member depth of compressive zone x

X=h₀-[h₀ ²-2×M/(α₁×f_c×b_f')]^0.5Or

X=h₀-[h₀ ²-2×M/(α₁×f_c×b)]^0.55),

Wherein: α₁For coefficient, f_cFor mixed earth axial compressive strength, b_f' for compressive region flange width, b is the width of T-shaped or square-section;

E13, beam bottom reinforcement bars area A_sCalculating, specifically: as x≤h_f' time, should be b by width_f' square-section calculate beam bottom reinforcement bars area As, such as expression formula 6):

A_s=α₁×f_c×b_f'×x/f_yOr A_s=α₁×f_c×b×x/f_y6),

Wherein: α₁For coefficient, f_cFor mixed earth axial compressive strength, b_f' for compressive region flange width, x is flexural member depth of compressive zone, f_yFor Steel Bar Tensile Strength design load;

E14, relative height of compression zone ξ, ratio of reinforcement ρ, minimum steel ratio ρ_minAnd most girder bottom reinforcement bars area A_s,minCalculate, concrete adopt expression formula 7), 8), 9) and 10), as follows:

ξ=x/h₀7);

ρ=A_s/(b×h₀) 8);

ρ_min=Max{0.20%, 0.45f_t/f_y9);

A_s,min=b × h × ρ_min10);

Wherein, f_tFor mixed earth axial tensile strength, A_sFor beam bottom reinforcement bars area, b is the width of T-shaped or square-section, and h is the height of T-shaped or square-section, f_yFor Steel Bar Tensile Strength design load.

E2, Beams Oblique Section Carrying Capacity calculate, and specifically include:

E21, Beams Oblique Section Carrying Capacity V ' calculating refer to expression formula 11),

V '=0.7 × f_t×b×h₀11), wherein: f_tFor mixed earth axial tensile strength, b is the width of T-shaped or square-section;

When Beams Oblique Section Carrying Capacity be more than or equal to the height of shearing force design value and T-shaped or square-section more than 800mm time,

Stirrup minimum diameter is 8mm, and between adjacent stirrup, maximum spacing is 400mm, joins hoop area by expression formula 12) obtain, A_sv,min=D_min2×0.25×π×s/s_max12), wherein: D_minRefer to stirrup minimum diameter, s_maxReferring to maximum spacing between adjacent stirrup, s refers to the distance between adjacent stirrup.

The main thought of grillage model is: superstructure one equivalent plan grid or space frame are simulated, will be dispersed in the bending stiffness in board-like or each section of box beam and torsional rigidity concentrates in closest equivalent beam grid, the longitudinal rigidity of practical structures concentrates in longitudinal beam lattice piece, lateral stiffness then concentrates in transverse beam lattice piece, boundary condition then adopts Winker to suppose to simulate elastic foundation, and its vertical support rigidity is actual measurement bedding value Ks ground contact area A corresponding to beam lattice cell node_soil。

The present invention tries to achieve the internal force of anchor beam, Bars In Poured Concrete Slab in grillage model application being designed to jacking construction middle slide plate first by grillage model, according to existing specification arrangement of reinforcement, can make up the shortcoming relying on Experience Design slide plate, it is provided that a kind of new sled design method.

The present invention uses sensitivity analysis theoretical, according to geological conditions, frame bridge scale, execution conditions etc., slide plate is designed, specifying jacking construction middle slide plate design middle slide plate thickness be key parameter, concrete strength is minor parameter, point the direction for sled design, improve the degree of accuracy of sled design.

The present invention sketches sled design and provides practicable thinking, and tries to achieve counter-force according to grillage model and verify whether to need to carry out basement process, improves the matching degree of slide plate and construction, improves efficiency of construction and construction quality.

The whole design optimization method process of the present invention is simplified, it is simple to practice, is beneficial to and promotes the use of.

Except purpose described above, feature and advantage, the present invention also has other purpose, feature and advantage. Below with reference to figure, the present invention is further detailed explanation.

Accompanying drawing explanation

The accompanying drawing constituting the part of the application is used for providing a further understanding of the present invention, and the schematic description and description of the present invention is used for explaining the present invention, is not intended that inappropriate limitation of the present invention. In the accompanying drawings:

Fig. 1 is the general arrangement of the embodiment of the present invention 1 working pit and slide plate;

Fig. 2 is the Space Beam lattice model schematic diagram of Fig. 1 middle slide plate;

Fig. 3 is the partial view of Fig. 2 middle slide plate;

Wherein, 1, slide plate, 11, longeron, 12, virtual crossbeam, 2, backfill soil, 3, rear parados, 4, steel shield structure, 5, horizon.

Detailed description of the invention

Below in conjunction with accompanying drawing, embodiments of the invention are described in detail, but the multitude of different ways that the present invention can limit according to claim and cover is implemented.

Embodiment 1:

Wearing a long highway jacked frame bridge project under the western extensions in Folium Salicis Babylonicae main road, referring to Fig. 1, Details as Follows:

A kind of method that sled design optimizes, comprises the following steps:

Step A, preparation process, specifically include the acquisition of parameter, sensitivity analysis and actual measurement bedding value, and the acquisition of parameter specifically obtains following parameter:

Compressive strength of concrete f_cu,kFor 30N/mm², concrete axial compressive strength f_cFor 13.8N/mm², concrete axial tensile strength f_tFor 1.39N/mm², ultimate compressive strain of concrete ε_cuIt is 0.0033;

Steel Bar Tensile Strength design load f_yFor 300N/mm², reinforcing bar elastic modulus E_sFor 200000N/mm², reinforcing bar comprcssive strength design load f_y'For 280N/mm²And stirrup tensile strength design load f_yvFor 270N/mm²;

Moment-curvature relationship M is 108kN m, shearing force design value V when be the distance s between 90kN, adjacent stirrup be 200mm, sectional dimension b × h being 500mm × 900mm slide plate stringer designs is T section) or be square-section during the design of 2460mm × 200mm slide plate crossbeam), set h₀During for 857.5mm slide plate stringer designs) or 157.5mm (during the design of slide plate crossbeam);

Factor alpha₁Be 1.0, factor beta₁Be 0.8, compressive region flange width b_f' for 1500mm, the edge of a wing, compressive region height h_f' for 200mm, wherein: b is cross-sectional width, h is cross-sectional height;

Described sensitivity analysis is specifically: obtain the thickness of slab t that key parameter is slide plate of sled design optimization according to sensitivity computing formula₀, anchor beam thickness l₀, slide plate modulus of elasticity of concrete E_cAnd elastic bearing COEFFICIENT K_v, specifically: set sensitivity calculating formula as expression formula 1):

$S_j=\frac{\underset{1}{\overset{m}{\Σ}}{\mathrm{\ΔM}}_i^2/\underset{1}{\overset{m}{\Σ}}{M}_i^2}{|{\mathrm{\Δx}}_j/x_j|}---1),$

In formula, x_jFor jth design parameter, Δ x_jFor parameter x_jKnots modification; M_iFor force value in controlling sections before parameter change, Δ M_iFor parameter x_jValue changes Δ x_jRear controlling sections internal force knots modification; M is for controlling number of parameters, S_jRepresenting the sensitivity of jth parameter, j is the number of parameters participating in sensitivity analysis;

Each parameter affect percentages formula 2) as follows:

$S_j^{\′}=S_j/\underset{1}{\overset{N}{\Σ}}{S}_i\×100\%---2),$

In formula, N is affecting parameters number;

Analyze result such as table 1:

The prefabricated parameters sensitivity analysis completing the moment of table 1 jacked frame bridge

Sequence number	Parameter	Primary standard value	Sensitivity	Affect percentage ratio/%
					1	t0	30cm	0.0495	34.8
2	l0	50cm	0.0384	27.0
					3	Ec	3.0×107kN/m2	0.0196	13.8
4	Kv	3.96×105kN/m2	0.0347	24.4

As known from Table 1, the thickness of slide plate is maximum to slide plate stressing influence, for main control parameters and most sensitive parameter), slide plate modulus of elasticity of concrete sensitivity is more minimum, for minor parameter; Additionally, increase bedding value, slide plate stress is diminished, increase slide plate thickness and then cause that slide plate stress increases;

Described actual measurement bedding value is specifically: be specially according to " skyscraper geotechnical engineering investigation code " (JGJ72 2004) annex H relevant regulations according to relevant regulations) and experience obtain bedding value k_sFor 6022kN/m⁴And allowable bearing capacity of foundation soil [f_a0] for 140kPa;

Step B, just intend slide plate size, B.0.1 just intend slide plate size according to " CJJ74-99 cities and towns Subway Bridge jacking construction and control of acceptance " the 5.4.1 article and the, it is however generally that, bedding value less then slide plate thickness is relatively big, and bedding value is relatively big, and then slide plate thickness is less; Just intend size and then mainly include the parameters such as anchor beam size, thickness of slab, anchor beam spacing; Rule of thumb and correlation engineering example report, it is 20cm that thickness of slab can be intended to be 20-30cm slide plate minimum thickness); Anchor beam spacing takes 2m-3m, and anchor beam height is 50cm-80cm; Anchor beam width is 30cm-50cm, herein specifically: taking slide plate concrete strength is C30, and the thickness of slide plate is 30cm; Being shaped as of slide plate: right-angled trapezium, and be thick 30cm monolithic reinforced-concrete structures, refer to Fig. 1; For strengthening longitudinal slide and ground frictional resistance, the distance between adjacent anchor beam is 2.5m; The maximum deformation quantity of sled design is 5mm; The specification of anchor beam: anchor beam height is 70cm, anchor beam width is 50cm; For coordinating jacking, nose is arranged to oblique, and oblique angles is 63.881 °, and reserved about 2m length is as the place of assembled steel shield structure;

Step C, set up the space beam gird method of slide plate, grillage model theory specifically: taking vertical jacking direction band anchor beam is beam lattice longitudinal bar member, and slide plate beam lattice divide consider following factor:

Factor 1: beam lattice longitudinal bar member self cross section bending resistance the moment of inertia sum is equal to global sections bending resistance the moment of inertia;

Factor 2: for ensureing load transmission, transverse bar member spacing is no more than longitudinal beam rib spacing;

Factor 3: beam should ensure that orthogonal in length and breadth, crossbeam spacing is considered as the impact of slide plate leading edge oblique angles;

The longeron 11 taking slide plate is of a size of 2500mm × 300mm × 500mm × 700mm, and virtual crossbeam 12 is of a size of 2460mm × 300mm, refers to Fig. 3;

The checking computations of step D, base stress and maximum deformation quantity checking computations, specifically: calculate gained maximal support counter-force according to space beam gird method, maximum base stress value is obtained by maximum base stress computing formula, judge whether to need ground is processed by the size of maximum base stress value Yu allowable bearing capacity of foundation soil value, specifically:

Maximum base stress computing formula such as expression formula 3):

f_a=Fs/A_soil=562/ (2.5 × 2.46)=91.4kPa≤[f_a0]=140kPa3),

Wherein: f_aFor maximum base stress; Fs is that space beam gird method calculates gained maximal support counter-force; A is beam lattice cell node correspondence ground contact area;

Because maximum base stress is less than or equal to allowable bearing capacity of foundation soil, therefore ground does not need to carry out processing if desired to carry out basement process, then processing mode is with reference to " building foundation treatment technical specification " JGJ79-2012);

Obtaining maximum vertical deflection according to space beam gird method calculating is 1.420mm, because of the maximum deformation quantity 5mm that maximum vertical deflection is allowed less than slide plate), therefore, the size design of slide plate is reasonable, but, in view of the maximum deformation quantity that the maximum vertical deflection of slide plate is allowed much smaller than slide plate, slide plate thickness is partially thick, and directly another slide plate thickness is other parameter constants of 20cm, the thickness of slide plate selects to choose according to " CJJ74-99 cities and towns Subway Bridge jacking construction and control of acceptance " regulation minima, choose rule and generally take 20cm, 30cm, 35cm etc.), repeat and be calculated analysis and obtain: the change of maximum base stress is little, the maximum deformation quantity that slide plate is allowed is the 1.375mm maximum deformation quantity allowed less than slide plate), the design maximum moment of slide plate longeron is 108kN m and design maximum moment that minimal design moment is 90kN m and slide plate crossbeam is 110kN m and minimal design moment is-131kN m maximum deformation quantity herein, maximal bending moment and minimum moment of flexure all adopt computational methods of the prior art to obtain), it is satisfied by requirement,

It is 20cm that E, slide plate arrangement of reinforcement calculate now slide plate thickness), detailed process is as follows:

Slide plate stringer designs:

E1, flexure arrangement of reinforcement calculate, and comprise the following steps:

E11, relative limit depth of compressive zone ξ_bCalculate, particular by expression formula 4) calculate relative limit depth of compressive zone ξ_bValue, ξ_b=β 1/ [1+f_y/(E_s×ε_cu)]

=0.8/ [1+300/ (200000 × 0.0033)]=0.55004),

Wherein: f_yFor Steel Bar Tensile Strength design load, E_sFor reinforcing bar elastic modelling quantity, ε_cuFor ultimate compressive strain of concrete;

E12, the edge of a wing are positioned at the T-shaped by flanging or I-shaped cross-section flexural member depth of compressive zone x, it is known that As'=0mm²;

X=h₀-[h₀ ²-2×M/(α₁×f_c×b_f')]^0.55),

X=857.5-[857.5²-2×108000000/(1×13.8×2500)]^0.5

=3.64mm≤ξ_b×h₀=0.5500*857.5=472mm;

Wherein: α₁For coefficient, f_cFor mixed earth axial compressive strength, b_f' for compressive region flange width;

E13, beam bottom reinforcement bars area A_sCalculating, specifically: as x≤h_f'Time, should be b by width_f' square-section calculate:

A_s=α₁×f_c×b_f'×x/f_y6), wherein: α₁For coefficient, f_cFor mixed earth axial compressive strength, b_f' for compressive region flange width, x is flexural member depth of compressive zone, f_yFor Steel Bar Tensile Strength design load;

A_s=1 × 13.8 × 2500 × 3.7/300=425.5mm²;

E14, relative height of compression zone ξ, ratio of reinforcement ρ, minimum steel ratio ρ_minAnd most girder bottom reinforcement bars area A_s,minCalculating, Details as Follows:

Relative height of compression zone ξ=x/h₀7);

ξ=3.7/857.5=0.0043≤ξ_b=0.5500;

Ratio of reinforcement ρ=A_s/(b×h₀) 8);

ρ=421/ (500 × 857.5)=0.098%;

Minimum steel ratio ρ_min=Max{0.20%, 0.45f_t/f_y9);

ρ_min=Max{0.20%, 0.209%}=0.209%;

Most girder bottom reinforcement bars area A_s,min=b × h × ρ_min10);

A_s,min=500 × 900 × 0.209%=940mm²;

Wherein, f_tFor mixed earth axial tensile strength, A_sFor beam bottom reinforcement bars area, b is the width of T-shaped or square-section, and h is the height of T-shaped or square-section, f_yFor Steel Bar Tensile Strength design load;

E2, Beams Oblique Section Carrying Capacity calculate, and specifically include:

E21, Beams Oblique Section Carrying Capacity V ' calculating refer to expression formula 11),

V '=0.7 × f_t×b×h₀11),

Wherein: f_tFor mixed earth axial tensile strength, b is the width of T-shaped or square-section; V '=0.7 × f_t×b×h₀=0.7 × 1390 × 0.5 × 0.8575=417.2kN;

As Beams Oblique Section Carrying Capacity 417.2kN) be more than or equal to shearing force design value 90kN) and the height h=900mm of T-shaped or square-section) more than 800mm time, stirrup minimum diameter is 8mm, and between adjacent stirrup, maximum spacing is 400mm;

Join hoop area by expression formula 12) obtain, A_sv,min=D_min ²×0.25×π×s/s_max12);

A_sv,min=8²× 0.25 × π × 200/400=25mm², wherein: D_minRefer to stirrup minimum diameter, s_maxReferring to maximum spacing between adjacent stirrup, s refers to the distance between adjacent stirrup.

General flexural member, its Shear bearing capacity calculates by following equation:

V≤α_cv×f_t×b×h₀+f_yv×A_sv/s×h₀

R_v=0.7 × f_t×b×h₀=0.7 × 1390 × 0.5 × 0.8575=417.2kN >=V=90.0kN, it is only necessary to join hoop by structure, i.e. A_sv,min=25mm², stirrup minimum diameter φ 8, maximum spacing 400mm.

Slide plate crossbeam designs:

E1, flexure arrangement of reinforcement calculate, and comprise the following steps:

E11, relative limit depth of compressive zone ξ_bCalculate, calculate relative limit depth of compressive zone ξ particular by following expression_bValue, ξ_b=β 1/ [1+f_y/(E_s×ε_cu)]

=0.8/ [1+300/ (200000 × 0.0033)]=0.55004),

Wherein: f_yFor Steel Bar Tensile Strength design load, E_sFor reinforcing bar elastic modelling quantity, ε_cuFor ultimate compressive strain of concrete;

E12, Component in Single Rectangular Section or the edge of a wing are positioned at the T section flexural member depth of compressive zone x of tight side,

X=h₀-[h₀ ²-2×M/(α₁×f_c×b)]^0.55)

X=157.5-[157.5²-2×131000000/(1×13.8×2468)]^0.5

=26.65mm≤ξ_b×h₀=0.5500 × 157.5=87mm;

Wherein: α₁For coefficient, f_cFor mixed earth axial compressive strength, b_f' for compressive region flange width;

E13, beam bottom reinforcement bars area A_sCalculating, specifically: be calculated by following expression,

A_s=α₁×f_c×b×x/f_y, wherein: α₁For coefficient, f_cFor mixed earth axial compressive strength, b is surface member width, and x is flexural member depth of compressive zone, f_yFor Steel Bar Tensile Strength design load;

A_s=1 × 13.8 × 2468 × 21.7/300=2464mm²;

E14, relative height of compression zone ξ, ratio of reinforcement ρ, minimum steel ratio ρ_minAnd most girder bottom reinforcement bars area A_s,minCalculating, Details as Follows:

Relative height of compression zone ξ=x/h₀7);

ξ=26.65/157.5=0.169≤ξ_b=0.5500;

Ratio of reinforcement ρ=A_s/(b×h₀) 8);

ρ=2464/ (2468 × 157.5)=0.634%;

Minimum steel ratio ρ_min=Max{0.20%, 0.45f_t/f_y9);

ρ_min=Max{0.20%, 0.209%}=0.209%;

Most girder bottom reinforcement bars area A_s,min=b × h × ρ_min10);

A_s,min=2468 × 200 × 0.209%=1031mm²;

Wherein, f_tFor mixed earth axial tensile strength, A_sFor beam bottom reinforcement bars area, b is the width of T-shaped or square-section, and h is the height of T-shaped or square-section, f_yFor Steel Bar Tensile Strength design load;

E2, Beams Oblique Section Carrying Capacity calculate, and specifically include:

E21, Beams Oblique Section Carrying Capacity V ' calculating refer to expression formula 11),

V '=0.7 × f_t×b×h₀11),

Wherein: f_tFor mixed earth axial tensile strength, b is the width of T-shaped or square-section;

V '=0.7 × f_t×b×h₀=0.7 × 1390 × 2.46 × 0.1575=377.0kN;

As Beams Oblique Section Carrying Capacity V '=377.0kN) be more than or equal to shearing force design value 90kN) and the height h=200mm of T-shaped or square-section) more than 300mm time, stirrup minimum diameter is 6mm, and between adjacent stirrup, maximum spacing is 200mm;

Join hoop area by expression formula 12) obtain, A_sv,min=D_min ²×0.25×π×s/s_max12);

A_sv,min=6²× 0.25 × π × 200/200=28mm², wherein: D_minRefer to stirrup minimum diameter, s_maxReferring to maximum spacing between adjacent stirrup, s refers to the distance between adjacent stirrup.

General flexural member, its Shear bearing capacity calculates by following equation:

V≤α_cv×f_t×b×h₀+f_yv×A_sv/s×h₀

R_v=0.7 × f_t×b×h₀=0.7 × 1390 × 2.46 × 0.1575=377.0kN >=V=90.0kN, it is only necessary to join hoop by structure, i.e. A_sv,min=28mm², stirrup minimum diameter φ 6, maximum spacing 200mm.

By the present embodiment: rely on design experiences to carry out sled design overly conservative, slide plate thickness is partially thick, the present embodiment adopts the slide plate of 20cm, compared with the prior art: concrete amount surpasses 33.3%, amount of reinforcement surpasses 36.3%, herein the algorithm reference prior art of the consumption of concrete and reinforcing bar in slide plate. Current left width slide plate is constructed according to 20cm thickness, the specification of longeron arrangement of reinforcement: (1) longeron arrangement of reinforcement: 3, and diameter is 25mm, and square-section As is 1472mm²; (2) crossbeam arrangement of reinforcement: diameter is 10mm, spacing is 100mm, and square-section As is 1931mm². Current three frame bridge sections of having constructed, slide plate deformation without exception.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations. All within the spirit and principles in the present invention, any amendment of making, equivalent replacement, improvement etc., should be included within protection scope of the present invention.

Claims (7)

1. the method that a sled design optimizes, it is characterised in that comprise the following steps:

A, preparation process, specifically include the acquisition of parameter, sensitivity analysis and actual measurement bedding value, described sensitivity analysis is specifically: obtain, according to sensitivity computing formula, the key parameter that sled design optimizes, and the percentage ratio that affects according to each parameter determines most sensitive parameter; Described actual measurement bedding value is specifically: obtain bedding value value and allowable bearing capacity of foundation soil value according to relevant regulations and experience;

B, just intend slide plate size, specifically: select the maximum allowable deflection of the distance between slide plate concrete strength, the thickness of slide plate, adjacent anchor beam, the specification of anchor beam and slide plate according to designing requirement;

C, set up the space beam gird method of slide plate, specifically: the size according to the size of grillage model Design Theory slide plate longeron and virtual crossbeam, set support conditions according to bedding value, beam lattice unit size, calculate and obtain maximum deformation quantity, the design maximum moment of slide plate longeron and the design maximum moment of minimal design moment and slide plate crossbeam and the minimal design moment that slide plate is allowed;

The checking computations of D, base stress and maximum deformation quantity checking computations, specifically: obtain bearing reaction according to calculating, maximum base stress computing formula is utilized to obtain maximum base stress value, if maximum base stress value is less than or equal to allowable bearing capacity of foundation soil value, then ground need not be processed, otherwise need ground is processed;

Obtain maximum vertical deflection according to calculating, if the maximum deformation quantity that maximum vertical deflection is allowed less than or equal to slide plate, then described step B just intends slide plate Sizes, otherwise unreasonable; If described step B just intends slide plate Sizes, carry out next step; If the described off size reason of step B middle slide plate, then return step B after changing the value of most sensitive parameter;

E, slide plate arrangement of reinforcement calculate, and obtain slide plate longeron arrangement of reinforcement specification and slide plate longeron arrangement of reinforcement specification.

2. the method that sled design according to claim 1 optimizes, it is characterised in that in described step A, the acquisition of parameter includes the following parameter obtaining slide plate crossbeam or slide plate longeron:

Compressive strength of concrete, concrete axial compressive strength, concrete axial tensile strength and ultimate compressive strain of concrete;

Steel Bar Tensile Strength design load, reinforcing bar elastic modelling quantity, reinforcing bar comprcssive strength design load and stirrup tensile strength design load;

Distance between moment-curvature relationship, shearing force design value, adjacent stirrup, square-section or trapezoid cross section, factor alpha₁, factor beta₁, compressive region flange width and the edge of a wing, compressive region height.

3. the method that sled design according to claim 1 optimizes, it is characterised in that in described step A, sensitivity analysis is specifically:

Set sensitivity calculating formula as expression formula 1):

$S_j=\frac{\underset{1}{\overset{m}{\Σ}}{\mathrm{\ΔM}}_i^2/\underset{1}{\overset{m}{\Σ}}{M}_i^2}{|{\mathrm{\Δx}}_j/x_j|}---1),$

In formula, x_jFor jth design parameter, △ x_jFor parameter x_jKnots modification; M_iFor force value in controlling sections before parameter change, △ M_iFor parameter x_jValue changes △ x_jRear controlling sections internal force knots modification; M is for controlling number of parameters, S_jRepresenting the sensitivity of jth parameter, j is the number of parameters participating in sensitivity analysis;

Each parameter affect percentages formula 2) as follows:

$S_j^{\′}=S_j/\underset{1}{\overset{N}{\Σ}}{S}_i\×100\%---2),$

In formula, N is affecting parameters number;

The key parameter obtaining sled design is the thickness of slab of slide plate, the thickness of anchor beam, slide plate modulus of elasticity of concrete and elastic bearing coefficient, and the thickness of its middle slide plate is most sensitive parameter.

4. the method that sled design according to claim 1 optimizes, it is characterised in that in described step B: slide plate concrete strength is C30; The thickness of slide plate is 20-30mm; The maximum allowable deflection of slide plate is 5mm; Distance between adjacent anchor beam is 2-3m; The specification of anchor beam: anchor beam height is 50-80cm, anchor beam width is 30-50cm.

5. sled design according to claim 1 optimize method, it is characterised in that described step C central sill lattice law theory specifically: taking vertical jacking direction band anchor beam is beam lattice longitudinal bar member, slide plate beam lattice divide follow following factor:

Factor 1: beam lattice longitudinal bar member self cross section bending resistance the moment of inertia sum is equal to global sections bending resistance the moment of inertia;

Factor 2: for ensureing load transmission, transverse bar member spacing is less than longitudinal beam rib spacing;

Factor 3: beam ensures orthogonal in length and breadth, and crossbeam spacing is considered as the impact of slide plate leading edge oblique angles.

6. the method that sled design according to claim 1 optimizes, it is characterised in that maximum base stress computing formula such as expression formula 3 in described step D):

f_a=Fs/A_soil3),

Wherein: f_aFor maximum base stress; Fs is that space beam gird method calculates gained maximal support counter-force; A_soilFor beam lattice cell node correspondence ground contact area.

7. the method that sled design according to claim 1 optimizes, it is characterised in that

Described slide plate longeron or calculation of beam detailed process are as follows:

E1, flexure arrangement of reinforcement calculate, and comprise the following steps:

E11, relative limit depth of compressive zone ξ_bCalculate, particular by expression formula 4) calculate relative limit depth of compressive zone ξ_bValue,

ξ_b=β₁/[1+f_y/(E_s×ε_cu)] 4),

Wherein: f_yFor Steel Bar Tensile Strength design load, E_sFor reinforcing bar elastic modelling quantity, ε_cuFor ultimate compressive strain of concrete;

E12, the edge of a wing are positioned at the T-shaped by flanging or I-shaped cross-section flexural member depth of compressive zone or Component in Single Rectangular Section or the edge of a wing is positioned at the T section flexural member depth of compressive zone of tight side and calculates, specifically: by expression formula 5) calculating obtains flexural member depth of compressive zone x

X=h₀-[h₀ ²-2×M/(α₁×f_c×b_f')]^0.5Or

X=h₀-[h₀ ²-2×M/(α₁×f_c×b)]^0.55),

Wherein: α₁For coefficient, f_cFor mixed earth axial compressive strength, b_f' for compressive region flange width, b is the width of T-shaped or square-section;

E13, beam bottom reinforcement bars area A_sCalculating, specifically: as x≤h_f' time, it is b by width_f' square-section calculate beam bottom reinforcement bars area As, such as expression formula 6):

A_s=α₁×f_c×b_f'×x/f_yOr A_s=α₁×f_c×b×x/f_y6),

Wherein: α₁For coefficient, f_cFor mixed earth axial compressive strength, b_f' for compressive region flange width, x is flexural member depth of compressive zone, f_yFor Steel Bar Tensile Strength design load;

E14, relative height of compression zone ξ, ratio of reinforcement ρ, minimum steel ratio ρ_minAnd most girder bottom reinforcement bars area A_s,minCalculate, concrete adopt expression formula 7), 8), 9) and 10), as follows:

ξ=x/h₀7);

ρ=A_s/(b×h₀) 8);

ρ_min=Max{0.20%, 0.45f_t/f_y9);

A_s,min=b × h × ρ_min10);

Wherein, f_tFor mixed earth axial tensile strength, A_sFor beam bottom reinforcement bars area, b is the width of T-shaped or square-section, and h is the height of T-shaped or square-section, f_yFor Steel Bar Tensile Strength design load;

E2, Beams Oblique Section Carrying Capacity calculate, and specifically include:

E21, Beams Oblique Section Carrying Capacity V ' calculating refer to expression formula 11),

V '=0.7 × f_t×b×h₀11),

Wherein: f_tFor mixed earth axial tensile strength, b is the width of T-shaped or square-section;

When Beams Oblique Section Carrying Capacity be more than or equal to the height of shearing force design value and T-shaped or square-section more than 800mm time, stirrup minimum diameter is 8mm, and between adjacent stirrup, maximum spacing is 400mm, joins hoop area by expression formula 12) obtain, A_sv,min=D_min ²×0.25×π×s/s_max12),

Wherein: D_minRefer to stirrup minimum diameter, s_maxReferring to maximum spacing between adjacent stirrup, s refers to the distance between adjacent stirrup.