CN100519964C - Anti-pressure curve support for concrete sleeve - Google Patents

Abstract

The present invention relates to a concrete sleeve anti-buckling support, belonging to the field of civil engineering every dissipation and shock damping technology. Said invention substitutes steel pipe whose interior is filled up with concrete by adopting concrete sleeve. It is characterized by that the sectional dimension of concrete sleeve must be defined according to the stable and safety requirements; the longitudinal reinforcement dimension can be calculated according to the sectional anticrack equipments and the number of anti-extrusion hoop reinforcements and general hoop reinforcements and maximum diameter, minimum number and cutting position of longitudinal reinforcement can be defined according to the structure requirements.

Description

The anti-support of buckling of concrete sleeve

One, technical field

The anti-flexing of concrete sleeve supports (BRCB) and belongs to civil engineering structure energy-dissipating and shock-absorbing technical field, is mainly used in structural engineering, civil structure engineering.

Two, background technology

When needs increase lateral displacement stiffness of structure, improve structural seismic capacity, can use the anti-support of buckling when improving structural seismic performance, and it is installed between the important node of civil engineering structure (Fig. 1).Anti-lateral deflection is supported by the steel core, outside steel pipe and the connection fittings that scribble surperficial isolated material and establish tectonic gap and is formed filling concrete mortar or concrete in the space between steel core and the outside steel pipe.Steel core is only born when work and is drawn, pressure.Surface isolated material and tectonic gap can allow steel core flexible in outsourcing material, and outsourcing cement mortar and steel pipe can increase monolithic stability, avoid steel core pressurized unstability.Steel core before surrender for structure provides endurance and stiffness, but after surrender earthquake energy.Hysteresis loop has full, regular characteristics under course under cyclic loading, is better than ordinary steel greatly and supports (Fig. 3).

At present, the anti-support of mentioning in achievement in research of having delivered and the actual engineering found of buckling, the outsourcing parts are all made with steel pipe and concrete filled.Way with steel pipe and concrete filled is made outer tube, and the one, fireproof performance is inferior to concrete, and the 2nd, material and processing charges are higher, and the 3rd, non-square, non-circular steel pipe generally need special machining.As fire, steel pipe is impaired, and then resistance to compression Qu Gong can not get guaranteeing.Be mainly reflected on fireproof paint, rolled steel dosage and non-square/round steel pipe machining and material and processing charges are higher.If use the concrete for making sleeve pipe, need prevent that the accidental off-centre of steel core from causing outer tube to be subjected to curved and concrete cracking that cause.The buckle integral rigidity of sleeve pipe of cracking rear defence will reduce, and influence prevents buckling function.Need the relevant art support in this respect.

Three, summary of the invention

The objective of the invention is to use the anti-outer canning tube of buckling and supporting of concrete for making, solve the low and cost problem of higher of present outside steel pipe fireproof performance.Under the prerequisite that reduces cost, can support the equal effect of performance with anti-the buckling of outside steel pipe concrete filled.

The anti-support of buckling of a kind of concrete sleeve mainly comprises external wrapping concrete sleeve pipe and inner cage of reinforcement, scribbles surperficial isolated material and establishes the steel core of tectonic gap, it is characterized in that:

(1) cross section of concrete sleeve

The second moment of area of concrete sleeve must satisfy formula (a):

$I\&GreaterEqual;\frac{\mathrm{\&beta;}{N}_y{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="C200710099427E00171.png,C200710099427E00173.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}{{\mathrm{\&pi;}}^2{E}_c}---\left(a\right)$

In the formula,

The second moment of area of I reinforced concrete sleeve; N _yBe steel core surrender axle power, N _y=A _wf _y, A _wBe steel core section area, f _yBe steel core material yield intensity; E _cModulus of elasticity for concrete material; 1 is the anti-support calculated length of buckling, the entire length of desirable 1.0 times of supports when adopting bolt to connect.

The principle of formula (a) is the critical bearing capacity of resistance to compression of outer tube is surrendered bearing capacity greater than steel core β a times.Consider factors such as supporting monolithic stability, steel core high-order and local stability, steel core design safety factor, the anti-support β that buckles of steel sleeve concrete filled generally gets more than 2.5～3.Concrete sleeve β of the present invention gets 4.5～5 (but C30 and following concrete cappings).By the selected concrete outer tube of formula (a) sectional dimension,, can reach the effect that reduces accidental off-centre, increase stability, realizes crack resistance and rigidity control approximately than big by 10～15% with steel pipe concrete filled outer tube under the condition.

The outer contour shape of concrete jacket tube section has one of cross section of disymmetry axle for circular, square, rectangle, regular hexagon, octagon etc.

(2) cage of reinforcement in the concrete sleeve

Cage of reinforcement in the concrete sleeve is formed through welding, colligation by the additional stirrup 4 in longitudinal reinforcement 5, anti-extrusion stirrup 7, common stirrup 6 and end.Specific requirement is as follows.

1, longitudinal reinforcement

The sectional area of longitudinal reinforcement 5 should calculate respectively by formula (b) by two major axes orientations along the cross section:

$\frac{M}{\mathrm{\&gamma;}{W}_0}\&le;f_{\mathrm{ct}}---\left(b\right)$

In the formula,

M is for considering the moment of flexure of being born by concrete sleeve of initial eccentricity and second order buckling influence.M=N _ye ₀, e ₀Be accidental off-centre, $e_0=e_{0a}+\frac{3{\mathrm{<figure-callout\; id="2"\; label="f\; ct\; l"\; filenames="C200710099427E00171.png,C200710099427E00173.png"\; state="\{\{state\}\}">f</figure-callout>}}_{\mathrm{ct}}{l}^{}{}^2}{10h{E}_c},$ e _0aBe initial eccentricity, h by the depth of section of checking computations major axes orientation.

W ₀By comprise vertical muscle the cross-section elasticities resistance moment of checking computations major axes orientation, $W_0=W_c+({\mathrm{\&alpha;}}_s-1)\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{A}_{\mathrm{si}}{y}_i^2}{y_0},$ Wherein, W _cBe the concrete sleeve cross-section elasticities resistance moment of (not comprising steel core); A _SiSection area for the vertical muscle of i root in the concrete sleeve; N is a vertical muscle sum in the cross section; y _iBe the distance of the vertical muscle position of form center of i root to the cross section centre of form; y ₀Be the distance of the cross section centre of form to tension edge, cross section; α _sRatio for vertical muscle modulus of elasticity and modulus of elasticity of concrete.Vertical muscle section area $A_s=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{A}_{\mathrm{si}}.$

γ is concrete section plasticity opposing coefficient.To the square-section, γ=1.55; To circular cross-section, γ=1.6.

f _CtBe the concrete tensile strength design load.

Formula (b) seems identical with ordinary reinforced concrete flexural member Calculation of Crack Resistance formula, but different in itself.Anti-buckling is supported for the uniaxial force member.Owing to reasons such as foozle, material homogeneity, the deformations of member, the concrete jacket pipe component centre of form and steel core center of effort can exist certain accidental eccentric, and concrete sleeve is bent.It is maximum that the tensile stress at casing profile edge will reach, and the configuration longitudinal reinforcement will improve the horizontal anti-crack ability of concrete sleeve.Corresponding therewith, the concrete outer tube then plays a part to provide lateral restriction, prevents the whole unstability of side direction steel core.

Formula (b) is also different with the axis compression member in the steel work.The steel work axis compression member generally reflects the influence degree that the member slenderness ratio reduces member resistance to compression bearing capacity by the coefficient of stability.And anti-steel core and the contact pressure between the sleeve pipe that supports of buckling is interdependent each other, influence each other, and steel core belongs to the compressed member that is subjected to the nonlinear elasticity lateral restraint.Under effective lateral restraint condition, the resistance to compression bearing capacity of steel core can not reduce.In addition, exist relatively between steel core and the concrete sleeve and slide, the plane section stress distribution because of accidental off-centre is not consistent by curved back two kinds of cross sections lacks comparativity with slenderness ratio parameter reflection bearing capacity problem and common axis compression member.So the slenderness ratio parameter can't reflect the complex situations of sleeve stress, the thinking of steel work axis compression member can not be directly used in the anti-supporting member of buckling.

The present invention with the permission alignment error of the crooked rise of general steel work compressed member and concrete component cross section allowable dimension variation as initial eccentricity (e _0a), studied concrete sleeve as the nonlinear elasticity confining part in the maximum deflection stretching strain that can allowed by curved back, the size of the support second order buckling lateral deflection of preventing buckling and sectional curvature be along the regularity of distribution of axis, in conjunction with the experimental test result, provided outer tube and under the steel core yield condition, born the computational methods of moment M, provided the design formulas (b) of vertical muscle requirement in the sleeve pipe with the form of control sleeve pipe crack resistance.

2, anti-extrusion stirrup

During the steel core surrender, lateral strain reaches vertical pressurized yield strain and multiply by poisson's ratio.Analysis and test show that the lateral strain peak discharge after the surrender can increase to 1.5-2.0 times of this value.Leave the tectonic gap that can hold this distortion in the concrete sleeve.Tectonic gap can not be excessive, in case steel core high-order unstability.Owing to making reasons such as error, material homogeneity, still there is the outer squeezing action that rises between steel core and the outer tube.This outer squeezing action that rises produces the hoop tensile stress in concrete sleeve.

For reducing the hoop tensile stress in the concrete sleeve, increase the anti-extrusion ability of concrete, improve vertical anti-crack ability of concrete sleeve, be provided with anti-extrusion stirrup 7.Compound stirrup effect in this stirrup and the ordinary concrete axis compression member different (latter's purpose is to prevent to indulge muscle and buckles, and particularly allows the vertical muscle that is in the section edges centre position also be subjected to operative constraint).The design of anti-extrusion stirrup 7 shapes depends primarily on the steel core pressurized formed hoop tensile stress field in concrete sleeve of rising outward.The analysis showed that, select for use anti-extrusion stirrup 7 effects of shape shown in Fig. 5,6 best.The surrender of invar core pressurized can occur in the whole active section, and stirrup 7 should evenly arrange that its spacing, diameter are determined by the relative configurations requirement in the specific embodiment along the sleeve pipe total length.For it is played one's part to the full, anti-extrusion stirrup 7 should be welded by Fig. 6 requirement, can form cage of reinforcement with vertical muscle colligation.

Advantage of the present invention and benefit are:

1. the present invention uses steel concrete as the anti-support of buckling of confinement sleeve manufacturing, compares with the anti-flexing support that the steel pipe concrete filled is made, and has improved fire resistance and decay resistance.Support under the condition that maintains an equal level anti-the buckling of assurance anti-seismic performance, fireproof performance and common steel tube concrete filled, making, the anti-total cost that supports of buckling of installation reduce about 15% at least.

2. the anti-support applications of buckling provided by the invention is extensive, can install and use in steel work, steel composite construction, concrete structure, all can use new construction and existing structure stabilization works.

3. compare with the building structure of using traditional anti-seismic technology, use the present invention can reduce the construction costs, the minimizing that cause because of assurance structural seismic demand greatly and shake post-reinforcing and rehabilitation expense.

4. manufacture craft is simpler, design, easy for installation, non-maintaining, replaceable.

Four, description of drawings

Anti-certain (X font) the installation situation and the ordinary construction of buckling and supporting of Fig. 1 concrete sleeve

The anti-internal structure of buckling and supporting of Fig. 2 concrete sleeve

Wherein: 1 steel core; 2 reinforced concrete sleeves; 3 surperficial isolated material and tectonic gaps; 4 ends add stirrup; 5 longitudinal reinforcements; 6 common stirrups (colligation forms); 7 anti-extrusion stirrups (being welded).

The comparison of the axle power-racking test curve of Fig. 3 anti-buckle support and common support

Wherein, (a) common support; (b) the anti-support of buckling.

Fig. 4 concrete sleeve cross-section elasticities resistance moment calculating parameter schematic diagram

Wherein, A _SiSection area for the vertical muscle of i root in the concrete sleeve; y _iBe the distance of the vertical muscle position of form center of i root to the cross section centre of form; y ₀Be the distance of the cross section centre of form to the cross section under tension edge.

Fig. 5 concrete sleeve and steel core section structure

Wherein, (a) " one " font steel core circular casing; (b) " ten " font steel core square casing; (c)

" ten " font steel core circular casing; (d) " worker " font steel core square casing.

The form of common stirrup of Fig. 6 and anti-extrusion stirrup

Wherein, (a) common welding ring stirrup; (b) common square colligation stirrup; (c) the supporting anti-extrusion stirrup of " one " font steel core; (d) the supporting anti-extrusion stirrup of " ten " font steel core; (e) the supporting anti-extrusion stirrup of " worker " font steel core; d _vBe anti-extrusion stirrup diameter.

The vertical muscle of Fig. 7 cuts off and the end stirrup is encrypted the structure requirement

Wherein: l _cThe concrete jacket length of tube; As indulges the muscle total cross-sectional area.

The anti-work segmentation of buckling and supporting of Fig. 8 concrete sleeve

Wherein: (1) active section; (2) changeover portion; (3) linkage section; (4) inoperative section; l _lLinkage section length; l _tTransition section length; l _wActive section length; l _cThe concrete jacket length of tube; The anti-support entire length of buckling of l.

Fig. 9 is provided with anti-framework that supports or the framework first layer plane arrangement diagram that center support is set of buckling

Wherein: in the anti-framework that supports of buckling is set, the first floor～3rd layer whole " ten " font cross section steel core that uses, the 4th layer is used " one " font cross section steel core, sees table 1 for details.Show the anti-support position of buckling, two kinds of cross sections among Fig. 9.1. the anti-support of buckling of " one " font cross section steel core has been adopted in expression; 2. the anti-support of buckling of " ten " font cross section steel core has been adopted in expression.

Analysis result is covered in pushing away of three kinds of frameworks of Figure 10

Figure 11 interlaminar shear distributes and heavily distributes rule

Five, the specific embodiment

1, the design of the anti-flexing support of concrete sleeve

(1) the preliminary earlier endurance and stiffness of determining the anti-support of buckling:

(GB50017-2003) post of main frame structure, the cross section of beam are selected in the requirement of vertical load bearing capacity and vertical displacement according to " Code for design of steel structures ".For guaranteeing that lateral displacements satisfies code requirement under maximum wind action, on main body frame, set up the anti-support of buckling, endurance and stiffness is provided jointly, determine the anti-total endurance and stiffness and the quantity of buckling and supporting thus.

(2) anti-buckling supported the calculating of steel core section:

After step (1) has been determined the support endurance and stiffness, carry out geological process calculating to the anti-framework that supports of buckling is set, and determine to support the internal force of being born according to the collaborative work or the rigidity ratio of framework and support.According to the selected anti-cross section of buckling and supporting of this internal force.After sectional area is determined, utilize formula of the present invention (3) to calculate active section length.

In this step, delay anti-surrender opportunity, the raising structural entity antidetonation surrender level of buckling and supporting as need, can also utilize the present invention further to increase the section area of the anti-support of buckling, thereby receive the effect that " based on the seismic design of condition " can reach.

(3) design of concrete sleeve:

(1) and (2) set by step, steel core active section sectional dimension are to determine according to the required surrender level of structure design, and steel core active section length is to determine according to the required rigidity requirement of structure design.After determining support stiffness, section area, active section length, utilize formula of the present invention (a) and the requirement of relevant structure, determine the construction size of concrete sleeve.Calculate the longitudinal reinforcement area by formula (b), initial eccentricity is got e _0a=10mm.

It is the concrete of C25-C40 that concrete sleeve is selected intensity rank for use.Steel core is selected one of Q235 or Q345 steel for use, and stirrup adopts HPB235, and vertical muscle adopts HRB335, and isolated material adopts silica gel.

The structure requirement of concrete sleeve

1., the smallest cross-sectional size of concrete sleeve: h _Min=max (200mm, 1/20), wherein 1 is the anti-support entire length of buckling, anti-the buckling of 1=supported distance-component node size between the frame joint that is connected.

2., arrangement of reinforcement encrypted area: anti-buckling supported concrete sleeve two ends l _cIn/8 scopes is the stirrup encrypted area, middle l _cBe vertical muscle normal range (NR), l in/2 scopes _cBe the concrete jacket length of tube.See Fig. 7,8 for details.

3., vertical muscle 5 and common stirrup 6 need satisfy following requirement:

Vertical muscle 5 cuts off 20% at most in the l/4 length range of concrete sleeve two ends.Common stirrup is encrypted in the l/8 scope of end.

H〉during 300mm, common stirrup φ 6@200, encrypted area φ 6@50;

All vertical muscle minimum sectional area A _{S, min}=1.25%A _c

During h≤300mm, common stirrup φ 5@150, encrypted area φ 5@50;

All vertical muscle minimum sectional area A _{S, min}=1.50%Ac.

Maximum vertical muscle diameter, d _{S, max}=min (18, h/16).

4., the additional stirrup 4 in anti-extrusion stirrup 7 and end is determined in the requsst listed below:

Anti-extrusion stirrup needs along the elongated configuration of member.Stirrup diameter d _v, to in-line steel core section, d _v(6,0.4t), t is a steel core steel plate thickness to=max; To cross and I-shaped, d _v=max (8,0.5t).Distance s _v=max (100, h/2).Component ends is established additional stirrup 4, and diameter and shape are with anti-extrusion stirrup.

2, the anti-axial rigidity K that buckles and support _aCan calculate by formula (3):

$K_a=\frac{1}{\frac{1_w}{E_s{A}_w}+\frac{1_t}{E_s{A}_t}+\frac{1_1}{E_1{A}_1}}---\left(3\right)$

E in the formula _s, E ₁Be respectively steel core and the modulus of elasticity that is connected steel, 1 ₁, A ₁Linkage section length, sectional area; 1 _t, A _tSteel core transition section length, sectional area; 1 _w, A _wSteel core active section length, sectional area.

3, the anti-making and the installation of buckling and supporting of concrete sleeve

Production process:

(1) preparation of steel core: make by structure design and manufacture craft requirement.

(2) isolated material and tectonic gap: select isolated material by designing requirement, by the manufacture craft requirement isolated material is placed steel core surface, tectonic gap adopts the stickup way to press the gap thickness designing requirement and reserves.

(3) making of concrete sleeve: formwork (template is reusable during batch process), the assembling reinforcement skeleton is placed steel core and temporary fixed.Concrete is pressed strength grade designing requirement proportioning (needing to use water reducing agent), concreting, control vibrating time.Maintenance, form removal.

Installation procedure:

(1) hoisted in position requires: select suspension centre at the two ends of steel core connecting portion.Back in place is temporary fixed.Elder generation's installing and locating bolt.By the requirement control support of Steel Structure Installation tecnical regulations and the installation deviation between the frame joint plate.

(2) bolt connection request: the anti-support of buckling of concrete sleeve should use bolt and related accessory to be connected with the frame joint plate.Diameter and quantity by the selected bolt of designing requirement.With torque spanner control erection bolt pretightning force.Adopt the carbon steel bolt, bolt pretension Stress Control value is 0.65 times of YIELD STRENGTH.The screw-down torque coefficient gets 0.2.

4, embodiment

Certain four layers of steel framed structure, the about 5000m of building area ², first floor height 4.8m, standard floor height 4.2m, structure height overall 17.4m.Adopt profiled sheet overlapping layers superstructure, the flooring live load is 2.5kN/m ² Seismic fortification intensity 8 degree, the basic earthquake acceleration 0.2g of structure, II class place, the design earthquake is grouped into first group.

(1) the anti-design of buckling and supporting of steel framed structure type selecting and concrete sleeve

1. the type selecting of main body steel framed structure, the anti-endurance and stiffness of buckling and supporting

The colum network size of main frame structure is determined in requirement according to building function, (GB50017-2003) post of main frame structure, the cross section of beam is selected in the requirement of vertical load bearing capacity and vertical displacement according to " Code for design of steel structures ".For guaranteeing the requirement of lateral displacements satisfied " Code for design of steel structures " under maximum wind action, on main body frame, set up the anti-support of buckling, endurance and stiffness is provided jointly, determine the anti-total endurance and stiffness and the quantity of buckling and supporting thus.The anti-support of buckling also will be resisted geological process with main body frame.

2. the calculating of the anti-supporting section of buckling

Utilize the anti-support stiffness of buckling of concrete sleeve steel of the present invention characteristics adjustable and that the surrender bearing capacity is adjustable to calculate section area.Specifically be after step 1) has been determined the support endurance and stiffness, to carry out geological process calculating to the anti-framework that supports of buckling is set, and determine to support the internal force of being born according to the collaborative work or the rigidity ratio of framework and support.According to the selected anti-cross section of buckling and supporting of this internal force.After sectional area is determined, with formula (4) evaluation work segment length.

Table 1: table is selected in the anti-design of supporting steel core of buckling for use

Layer	Direction	Support stiffness kN/mm	Active section section area mm 2	Active section length m m	Tension surrender bearing capacity kN	Select plate size in fact	Steel plate sectional area mm 2	Quantity
									4	X	77	1000	4000	300	①85×20	1700	4
3	X	161	2080	4000	624	②90×20	3600	4
									2	X	229	2960	4000	888	②125×20	5000	4
1	X	219	2960	4277	888	②125×20	5000	4
									4	Y	76	820	3355	246	①75×20	1500	8
3	Y	163	1773	3355	532	②75×20	3000	8
									2	Y	209	2267	3355	680	②100×20	4000	8
1	Y	218	2600	3679	780	②110×20	4400	8

* annotate: 1. the anti-support of buckling of " one " font cross section steel core has been adopted in expression; 2. the anti-support of buckling of " ten " font cross section steel core has been adopted in expression.The two concrete structure as shown in Figure 5.

3. the anti-design of buckling and supporting

According to step 1), 2) support stiffness, section area, the active section length result that determine, designed go out anti-buckle to support list in table 1.Under the prerequisite that guarantees rigidity, sectional area and active section length, real type selecting steel can also be adopted other section forms shown in Figure 5.But be convenient construction and processing and fabricating, reduce the product specification kind as far as possible.When specifically on the structural plan, arranging, according to symmetry, evenly, the principle that helps reducing construction torsion carries out.Be selected in architectural appearance, the impregnable position of function of use.Anti-the buckling of this case supported by " * " font (Fig. 1) installation, and particular location is referring to Fig. 9, and wherein, X establishes 4 altogether to every layer and prevents buckling supports, and Y establishes 8 anti-supports of buckling altogether to every layer.The material of steel core is homemade Q235 steel, and yield strength is pressed 300MPa and calculated.

4. concrete sleeve design

According to table 1 design-calculated steel core surrender bearing capacity, the design concrete sleeve also carries out cracking computation.Selecting intensity rank for use is the concrete (f of C30 _t=1.43MPa), require to determine the concrete sleeve design section according to formula (1) and structure.Determine vertical rib area by formula (2).Design procedure sees Table 2.

Determining and crack resisting calculation of table 2 concrete sleeve sectional dimension

5. the anti-fabrication and installation of buckling and supporting: undertaken by following 5 steps.

A. manufacture steel core according to the selected steel plate of table 1 cross section.(X-axis and Z axle intersection point among Fig. 8) welding one spacing card in the steel core middle part.The available bolt of spacing card, angle cleat etc. are made.

B. smear isolated material in steel core surface.Wait to tie hard back and paste the tectonic gap material, the gap width at steel plate acropodium position and other position is by the designing requirement value.

C. formwork is put into cage of reinforcement with steel core, and the two is put into template and does temporary fixed.

D. in the space of template, reinforcing bar and steel core concreting and maintenance to design strength, form removal.

E. main frame structure construction, welding node plate and necessary put more energy into, connect material, anti-the buckling of lifting supported and with torque spanner connecting bolt screwed.

(2) structural seismic effect analysis and contrast

1. structural calculation model

For saying something, this case has designed three kinds of structural systems: anti-the buckling of concrete sleeve of the present invention supported steel frame (BRCB framework), center support steel frame (NB framework) and ordinary steel framework.Three kinds of structure Design conditions are identical, and the latter's seismic design of structures (GB50011-2001) is carried out with reference to existing national standard " seismic design provision in building code ".Frame-generic member section determining dimensions not only will satisfy the static(al) requirement for bearing capacity, also will satisfy the seismic design requirement.The beam of center support framework and the anti-support frame of buckling, column cross-section size determine that according to the vertical bearing capacity checking computations are preliminary the antidetonation bearing capacity is by framework and support common guarantee.

The Static Elasto-Plastic Analysis method (push away and cover analytic approach) of using " seismic design provision in building code " to allow is calculated and is analyzed FEM (finite element) model.Plastic hinge is established to simulate the stressed behavior after in a single day member enters elastoplasticity in its central sill, post bending component unit, beam, styletable.Superstructure adopts the plate unit, on add area load.Center support adopts an axle power bar unit, establishes pressurized critical force limit value, surpasses this critical force and then thinks component failure.Anti-buckling supported the non-linear axle of employing power unit, and the restoring force model adopts nonlinear model.Push away that to cover the loading mode that analytic approach adopts be that del loads continuously.Dead load, live load, wind load are static load, once apply to finish.

2. result of calculation comparison and analysis

Figure 10 covers the shearing-relative storey displacement result who analyzes gained first floor intermediolateral column for X to pushing away.As can be seen from this figure, the frame column (the NB framework among the figure) of band center support is approaching with the initial stiffness of the anti-carriage trestle (the BRCB framework among the figure) of buckling of band, but when side direction pushes away the power of covering and reaches certain level, the whole unstability of center support meeting occurrence of large-area of pressurized, supporting capacity can reduce suddenly, can't realize the target of no collapsing with strong earthquake.The anti-framework of buckling and supporting of band, because the anti-support rate of buckling is introduced into surrender stage earthquake energy, structural entity rigidity can corresponding reduction, but supporting capacity can not reduce, and structural entity ductility and energy dissipation capacity improve greatly.As can be seen from Figure 10, in the middle of three kinds of structures, have only the BRCB framework to reach the three levels target of providing fortification against earthquakes fully.The frame-generic rolled steel dosage is many, and big shake has a large amount of beams, post member to enter yield situation down, and permanent set is bigger, shake back rehabilitation expense height.

The anti-support frame of buckling pushes away the power of covering in side direction to begin to load in the process of the displacement that reaches capacity, and the distribution of interlaminar shear and heavy distribution condition are plotted among Figure 11.As can be seen, at elastic stage, anti-buckling supported total interlaminar shear of bearing 62%-78%, and all keeps this ratio constant substantially in this stage.Cover to the 18th step when pushing away, yield phenomenon appears in each layer anti-support of buckling successively.Simultaneously, begin to increase in the ratio of bearing with the framework pillar of layer position of cutting of holding.Be pushed into for the 35th step during the left and right sides, a small amount of beam begins to occur yield phenomenon, causes the gathering way of interlaminar shear ratio of some floor frame-generic to descend gradually.When surrender appears in the beam-ends cross section of some (after the 50th step), anti-buckling supported the interlaminar shear ratio of bearing with framework and maintained separately about 50%, covers end until pushing away.

In addition, further research and analyse and learn, if use the eccentric support frame or the bone shape tie-beam framework that have energy dissipating beam section, though the anti-support frame of buckling of structural seismic performance and this case maintains an equal level, but the permanent set that after excessive shake, in energy dissipating beam section, keeps, to make the superstructure and the enclosed structure that are attached thereto produce bigger expendable permanent set, repair difficulty increasing, expense raising.And the anti-support frame of buckling is to be cost with the yield deformation that supports, and main body frame or most framework (depending on designing requirement) can keep elasticity, and the enclosed structure distortion of depending on it is less, also just reduced rehabilitation expense.The anti-support of buckling belongs to metal yield type damper, does not need regular maintenance, has reduced the lifelong cost of building effectively.Even indivedual anti-buckling are supported the appearance damage, also are to change easily.

(3) cost-efficiency analysis

Support the cost performance of two kinds of members for comparing anti-the buckling of the present invention and common steel tube concrete filled, table 3 has been added up the unit price and the material cost price proportion of this case history (table 1 and table 2) used anti-the buckle total consumption of various materials of supporting sleeve, various materials.Give two kinds of fire prevention way, i.e. thick coated type fireproof paint or slim fireproof paints adopting usually in the present structural steelwork in the table.Two kinds of methods use material, construction technology, performance characteristics all different, see the note of table 3 for details.

As can be seen from Table 3, use the anti-support of buckling of concrete sleeve of the present invention, sleeve pipe itself need not sprayed fire proofing coating just can reach 2.5 hours standard of fire endurance.Use the anti-support (not sprayed fire proofing coating) of buckling of steel pipe concrete filled material, higher by 5% than material cost of the present invention, but being fireproof performance, problem is lower than the member of making of the present invention certainly.If at steel pipe outer surface sprayed fire proofing material, then the material cost of sleeve pipe and fireproof paint increases about 88% than concrete sleeve at least.If by the sleeve pipe cost account for anti-buckle support assembly this 20% estimate that then use the present invention will save anti-total material cost about 15% of buckling and supporting, this estimation does not also comprise the construction technology and the facility expense of fireproof paint in this engineering.

The material cost of two kinds of sleeve pipe ways of table 3 relatively

Note:

1, thick coated type steel structure fire-proof paint is heat insulation by noninflammability, the low heat conductivity of material.Adopt cementing agent, inorganic lightweight material and reinforcing material to make.Construction should be adopted the spraying of pressure sending type flush coater, and air pressure is 0.4～0.6MPa, and the gun slot diameter is preferably 6～10mm.Sequence of construction is: the bottoming of spray gun surface, coating thickness 1-1.5mm.After the sclerosis in 24 hours, can spray or smear, every time thickness is preferably 5～10mm.Smear for twice and be spaced apart 24 hours.Smear till the thickness that reaches design code.The weak point decorative surface is relatively poor.

Super-thin steel structure fire-proof paint is expanded foamed after heated up by fire, forms fine and close refractory insulating layer.Coating ultra-thin (3-7mm) is generally solvent-borne type, makes base-material with emulsion polymer, is equipped with fire retardant, additive etc. again and makes.Spraying method is adopted in construction.Characteristics such as adhesion strength height and water resistance, levelability, good decorative property.Weak point: the one, the fire-retardant composition in the coating discharges toxic gases such as NH3, CL2, BR2 meeting the fire back of expanding, and the 2nd, problem such as there is degraded under field conditions (factors) in the organic component in the material, wear out, durability is slightly poorer than the thick coated type fireproof paint.

2, experimental study both at home and abroad, country and industry standard still lack the detailed test study foundation at present.

3, unit price is selected from existing market guide prices such as Chinese building material net, Chinese detail estimate net respectively.

4, only count the Master Cost of concrete sleeve, outside steel pipe concrete filled two kinds of ways in the table, do not comprised expenses such as steel core, connector.The expense that does not count also comprises: the labour cost of concrete blinding expense (can use typing turnover template), cage of reinforcement processing labour cost, non-standard steel pipe processing charges, sprayed fire proofing material and machinery expense, material aging renovation expense etc.

5, conclusion

Used the anti-support of buckling of concrete sleeve of the present invention among the embodiment.The anti-support of buckling of two kinds of steel core structures, four kinds of active section length, six kinds of steel core cross dimensionss has been installed respectively in vertical, horizontal.Obtained multiple (each floor is different) rigidity/surrender Design of Bearing Capacity parameter by adjusting active section length with section area, made structure possess necessary lateral deformation stiffness and antidetonation bearing capacity.

The analysis showed that use the anti-support frame structure of buckling of concrete sleeve of the present invention, force mechanism is clear and definite, the structure power consumption is stable, anti-vibration defense lines is reasonable, can realize fully that not bad, the middle shake of little shake can be repaiied, the target of providing fortification against earthquakes of no collapsing with strong earthquake, and anti-seismic performance is better than center support framework and frame-generic.Under big shake, can protect agent structure, non-structural element and ancillary facility effectively, realize seismic design of structures based on condition.Eccentric support frame with band energy dissipating beam section is compared with bone shape tie-beam framework, and the anti-support frame anti seismic efficiency of buckling of concrete sleeve maintains an equal level or omits.But the present invention is controlled at anti-buckling with yield deformation and supports inside, and shake back rehabilitation expense is low or be excused from a college course multiple.Simple structure of the present invention, non-maintaining, difficulty of construction is little, can install in the house decoration stage, to the construction condition that offers convenience.

Use the present invention supports under the condition that maintains an equal level anti-the buckling of assurance anti-seismic performance, fireproof performance and common steel tube concrete filled, and making, the anti-total cost that supports of buckling of installation reduce about 15% at least.

Claims (1)

1. anti-support of buckling of concrete sleeve, comprise external wrapping concrete sleeve pipe (2) and inner cage of reinforcement, scribble surperficial isolated material and establish the steel core (1) of tectonic gap (3), described cage of reinforcement is formed through welding, colligation by longitudinal reinforcement (5), anti-extrusion stirrup (7), common stirrup (6) and additional stirrup (4), it is characterized in that:

Use reinforced concrete sleeve to support the lateral restraint unit of steel core as anti-buckling;

The second moment of area of concrete sleeve need satisfy the requirement of formula (a):

$I\&GreaterEqual;\frac{\mathrm{\&beta;}{N}_y{1}^2}{{\mathrm{\&pi;}}^2{E}_c}---\left(a\right)$

The second moment of area of I reinforced concrete sleeve; N _yBe steel core surrender axle power, N _y=A _Coref _y, A _CoreBe steel core active section section area, f _yBe steel core material yield intensity; E _cModulus of elasticity for concrete material; L is the anti-support calculated length of buckling; β is a buckling safety factor;

The consumption of longitudinal reinforcement (5) is determined by formula (b) in the concrete sleeve:

$\frac{M}{\mathrm{\&gamma;}{W}_0}\&le;f_{\mathrm{ct}}---\left(b\right)$

In the formula, the moment of flexure of M for considering that initial eccentricity and second order buckling are born by outer tube calculated respectively by cross section two major axes orientations; M=N _ye ₀, e ₀For considering that anti-buckling support the eccentric throw that concrete sleeve produces because of initial eccentricity and second order buckling effect, $e_0=e_{0a}+\frac{3f_{\mathrm{ct}}{1}^2}{10h{E}_c},$ e _0aBe initial eccentricity, h by the depth of section of checking computations major axes orientation, f _CtBe concrete material tensile strength design load; γ is a concrete section resistance moment plastic coefficient; W ₀By comprise vertical muscle the reinforced concrete sleeve cross-section elasticities resistance moment of checking computations major axes orientation, $W_0=W_c+({\mathrm{\&alpha;}}_s-1)\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{A}_{\mathrm{si}}{y}_i^2}{y_0},$ Wherein, W _cThe cross-section elasticities resistance moment that does not comprise steel core for concrete; A _SiSection area for the vertical muscle of i root in the concrete sleeve; N is a vertical muscle sum in the cross section; y _iBe the distance of the vertical muscle position of form center of i root to the cross section centre of form; y ₀Be the distance of the cross section centre of form to tension edge, cross section; α _sRatio for vertical muscle modulus of elasticity and modulus of elasticity of concrete; Vertical muscle section area $A_s=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{A}_{\mathrm{si}}.$

Images