CN104989119A - Method for reinforcing wood structure joints by the use of angle iron - Google Patents

Abstract

The invention discloses a method for reinforcing wood structure joints by the use of angle iron. The method comprises following steps: determining whether joints are required to be reinforced; determining the linear rigidity ratio of beams and columns; determining the specification of the angle iron; determining the quantity of self-tapping screws; and determining the length of angle iron flanges. According to the invention, a scientific process for reinforcing the wood joints by the use of the angle iron is established, a mass of investigations and test experimental researches are carried out for determining the process, every parameter of the reinforcing process by the use of the angle iron is scientifically verified and determined, the wood joint reinforcing process is standardized and meets structure and mechanics demands, and the method contributes much to and can promote researches on wood structure anti-seismic and using aspects. Reinforcement materials can be easily obtained. The reinforcing method is simple, scientific and reasonable, and can be easily mastered by farmers. By employing the method, the construction is convenient, and substantial reinforcing effects can be achieved under a condition that the engineering cost is less. The construction can be carried out based on an original structure, and the method can be used together with other reinforcing manners.

Description

A kind of method adopting angle steel reinforced wooden construction node

Technical field

The present invention relates to a kind of reinforcement means, specifically a kind of employing angle steel reinforced node, to promote the method for node, house intensity.

Background technology

Wooden construction and post and panel structure due to history and economic dispatch reason distributed more widely in China rural area, especially in southwest, highly seismic region, northwest, also there is a large amount of timber frame load bearing constructions.Because these are all peasant's self-built housings, anti-seismic construction measure imperfection, especially position of joints is all much directly connect with straight tenon, and anti-seismic performance is poor.Shake higher once there is earthquake intensity, will constitute a serious threat to people's life and property safety.In Wenchuan earthquake, there is the phenomenon (as shown in Figure 1) such as pull-off tenon and folding tenon in a large amount of wooden construction node in the severely afflicated area such as southwest, river, Chuan Bei, Shan Nan, Gannan.

Traditional rural area wooden frame structure build process is more coarse, and many nodes of constructing for convenience directly connect with straight tenon and mortise is generally large than tenon, cause Tenon to load onto rear defective tightness.Because the hardness of timber is little, can there is drying shrinkage in timber itself, rural area wooden construction is not generally through anticorrosion damp-proof treatment simultaneously, and after certain time limit, tenon can corrode.These situations all can cause the connection defective tightness at tenon and the fourth of the twelve Earthly Branches above, the rigidity of Nodes is lower, when house is subject to the larger external force such as earthquake, wind-force, node will bear larger stretching, compression, shearing and twisting action, very easily cause and pull out tenon, phenomenon out of joint, make house that larger lateral displacement occur, even cave in (as shown in Figure 2).Tenon node is not due to through Specialty Design, and size is unreasonable and be corroded due to node, and the bearing capacity of node is lower, is being subject under larger external force, and folding tenon phenomenon will occur node.

The domestic way to wooden construction joint reinforcing mainly comprises at present: reinforce etc. node with dog, carbon cloth.When reinforcing with dog, its supporting capacity improves compared with before reinforcing.But the less and dog of dog rigidity is under course under cyclic loading, and its Stiffness Deterioration is very fast, destroys also very fast.In general, dog reinforcement measure has certain effect relative to before reinforcing, but this effect is also only just the displaying of stressed less Nodes of low crack area, is not clearly to highly seismic region and stressed larger Nodes effect.The price of carbon cloth reinforced measure is higher and construction is more inconvenient, uses be restricted in rural area.

Summary of the invention

For above-mentioned problems of the prior art, the object of the invention is to, a kind of method is provided, relatively general goal is out of shape at bean column node, reinforce node with angle steel, the supporting capacity improving node prevents node from occurring folding tenon, improves connection stiffness, being limited in large External Force Acting lower room, may to produce large sidesway original out of joint and pull out tenon phenomenon to improve, and then improve the anti-seismic performance in house.

In order to realize above-mentioned task, the present invention by the following technical solutions:

Adopt a method for angle steel reinforced wooden construction node, the two ends of described angle steel, with wing plate, after following step determination angle steel specification, utilize the wing plate at angle steel two ends to be connected with beam, post by self-tapping screw:

Step one, measure the rotational angle of the node that needs reinforcement, predicate node, the need of reinforcing, as needed reinforcement, performs step 2;

Step 2, determine the line stiffness ratio β of beam and column:

When the cross section of beam/post is circular, Line stiffness i is:

$i=\frac{{\mathrm{\α}}_1{\mathrm{\α}}_2{\mathrm{\πEd}}^4}{64l}$ Formula 1

When the cross section of beam/post is rectangle, Line stiffness i is:

$i=\frac{{\mathrm{\α}}_1{\mathrm{\α}}_2{\mathrm{\πEbh}}^3}{12l}$ Formula 2

In formula 1 and formula 2, E is the Deflection Modulus of Elasticity of beam/post, and d is the diameter of the circular cross-section of beam/post, and b is the wide of the circular cross-section of beam/post, and h is the height of the circular cross-section of beam/post, and l is the length of beam/post;

Parameter alpha ₁span be [0.90,0.95], parameter alpha ₂span be [0.80,0.95];

The line stiffness ratio β of beam and column is:

formula 3

Step 3, determine the specification of angle steel:

The length l of angle steel _yspan is l is beam span;

The section area S of angle steel _ydemand fulfillment following formula 5:

$S_y\≥\frac{fSR}{2f_y}(\frac{1}{l_y}+\frac{6+4\mathrm{\β}}{l_1})$ Formula 5

In formula 5, S is the section area of beam, and R is depth of section or the diameter of beam, and β is the line stiffness ratio of beam and column, f _yfor angle steel compressive strength design load, l ₁for the length of beam, f is the equivalent strength of timber, and value is scope is [4.1,7.2].

Further, described method also comprises step 4:

Step 4, determine self-tapping screw number:

Formula 6 is utilized to calculate the use number n of self-tapping screw:

$n=\frac{f_{v}S}{f_1{{\mathrm{\πr}}_1}^2}$ Formula 6

In formula 6, f _vfor the shear strength design load of beam timber used, S is the section area of beam, f ₁for the shear strength design load of self-tapping screw, r ₁for the radius of self-tapping screw;

Further, described method also comprises step 5:

Step 5, determine angle steel wing plate length:

The wing plate length l of angle steel _cspan be:

(3n ₂+ 1) d ₀≤ l _c≤ (16n ₂-8) d ₀formula 7

In formula 7, n ₂for the row of self-tapping screw on wing plate length direction, round;

N ₁for the row of the self-tapping screw on wing plate width, n ₁meet formula 8:

$\frac{b_y-8d_0}{16d_0}\≤n_1\≤\frac{b_y-4d_0}{3d_0}$ Formula 8

In formula 8, b _yfor wing plate width, d ₀for the diameter of self-tapping screw.

Further, when described angle steel specification is determined, angle steel is demand fulfillment also:

$13.5\frac{b_y}{t_y}+{\left(\frac{l_y}{b_y}\right)}^2\·\frac{t_y}{b_y}\≤170$ Formula 9

In formula 9, b _yfor angle steel width, t _yfor angle steel thickness, l _yfor angle steel length.

Further, the angle between the wing plate at described angle steel two ends and angle steel is 135 °.

Further, in described step one, predicate node the need of the concrete grammar reinforced is:

When the rotational angle of dovetail node is not less than 0.05rad, this node needs reinforcement;

When the rotational angle of straight tenon node is not less than 0.04rad, this node needs reinforcement.

The present invention compared with prior art has following technical characterstic:

1. the present invention establishes the scientific process utilizing angle steel reinforced knaur point, a large amount of investigations and experimental study is have passed through in the deterministic process of this flow process, scientifically prove, determine each parameter of angle steel reinforced process, make the reinforcing process standardization of knaur point and have the foundation meeting structure, terms of mechanics, having positive reference value and facilitation to the research of the aspects such as wooden building aseismicity, use;

2. reinforcement material is easy to get; Simple and the science of reinforcement means is closed, and reason is easily grasped by peasant; Construct more convenient, when less engineering cost, consolidation effect is more remarkable; Directly can construct on original structure and can use with the superposition of other reinforcement means.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of wooden construction node phenomenon out of joint;

Fig. 2 is the schematic diagram of the overall sidesway phenomenon of Wood construction;

Fig. 3 is the M-θ curve of wooden construction node;

Fig. 4 is the computation model of wooden construction node;

Fig. 5 is elevation and the lateral view of angle steel;

Fig. 6 is the installation site schematic diagram of angle steel;

Fig. 7 is the schematic diagram of simulation bumper test;

In Fig. 4 and Fig. 5: 1-post, 2-wooden construction node, 3-angle steel, 4-wing plate, 5-beam.

Detailed description of the invention

Adopt a method for angle steel reinforced wooden construction node, angle steel adopted in the method is board-type angle steel, the two ends of angle steel respectively with one for the wing plate with beam, pillar connection.After the specification of angle steel, parameter determine, by self-tapping screw, wing plate is connected with beam, pillar, to reach the object of reinforcing joint.Angle between the wing plate at angle steel two ends and angle steel is 135 °.Concrete step is as follows:

Step one, measure the rotational angle of the node that needs reinforcement, predicate node, the need of reinforcing, as needed reinforcement, performs step 2;

The Nodes of traditional rural area wooden frame structure generally adopts the connected mode of dovetail and straight tenon, therefore mainly studies these two kinds of structures in this programme.

By the moment-rotation relation drawn dovetail and straight tenon horizontal cyclic loading exteriment, i.e. M-θ curve, finding after their matchings that it is all sigmoid curve, just have any different in initial stiffness and surrender angle.In order to apply this curve, it being reduced to three sections further, as shown in Figure 3, being respectively elastic stage, yielding stage and decline stage.

From experiment skeleton curve above, we reach a conclusion when node enters yielding stage, the Stiffness Deterioration of node, and connection stiffness is very little.Then when knaur point is in this stage, the rigidity of node is very little, and resistance capacity to deformation is very little.Therefore, the object that we reinforce is exactly that node reaches yielding stage or decline stage.And binding tests result and discovery is investigated on the spot to the wooden frame structure in Shaanxi, Sichuan and Guizhou: the node of dovetail is generally when joint rotation angle is more than or equal to 0.05rad (unit is radian), and namely node enters yielding stage; When straight tenon joint rotation angle is for being more than or equal to 0.04rad (unit is radian), node enters yielding stage.

Therefore, the node needed reinforcement is: when the corner of dovetail node is more than or equal to 0.05rad, needs to reinforce; When the corner of straight tenon node is more than or equal to 0.04rad, need to reinforce.Other modes can certainly be adopted to determine that node is the need of reinforcing.

Step 2, determine the line stiffness ratio β of beam and column:

Find through experimental study and investigation, the cross section of the main and beam/post of the Line stiffness of beam/post, length, Deflection Modulus of Elasticity, parameter alpha ₁and parameter alpha ₂relevant, and meet following formula 1.Wherein, cross section and length can be obtained by field survey, and length is clear length (not comprising Nodes length); Deflection Modulus of Elasticity is different according to timber kind, and inquiry Code for design of timber structures 4.2.3 can obtain; Parameter alpha ₁and parameter alpha ₂obtain with investigation by experiment, as following table 1 and table 2.

When the cross section of beam/post is circular, Line stiffness i is:

$i=\frac{{\mathrm{\α}}_1{\mathrm{\α}}_2{\mathrm{\πEd}}^4}{64l}$ Formula 1

When the cross section of beam/post is rectangle, Line stiffness i is:

$i=\frac{{\mathrm{\α}}_1{\mathrm{\α}}_2{\mathrm{\πEbh}}^3}{12l}$ Formula 2

In formula 1 and formula 2, E is the Deflection Modulus of Elasticity of beam/post, and d is the diameter of the circular cross-section of beam/post, and b is the wide of the circular cross-section of beam/post, and h is the height of the circular cross-section of beam/post, and l is the length of beam/post; "/" represents "or", namely when the cross section of beam or post calculates for formula 1 time circular, calculates during rectangle by formula 2.

Parameter alpha ₁span be [0.90,0.95], parameter alpha ₂span be [0.80,0.95], more concrete can with reference to following table 1 and table 2:

Table 1 column parameter α ₁α ₂value table

House years already spent y	y＜5	5≤y＜20	20≤y＜50	50≤y
					α 1	1	0.95	0.90	0.90

α 2

1

0.95

0.90

0.80

Table 2 beam parameter alpha ₁α ₂value table

House years already spent y	y＜5	5≤y＜20	20≤y＜50	50≤y
					α 1	1	0.98	0.95	0.90
α 2	1	1	0.95	0.90

The Line stiffness of beam and column calculates by formula 1 or formula 2, then calculates:

The line stiffness ratio β of beam and column is:

formula 3

Step 3, determine the specification of angle steel:

Find that the strength grade of angle steel, length and section area are mainly relevant with the equivalent strength of the line stiffness ratio of beam column, beam length, beam section area and timber used after deliberation, it meets formula 4 below.The strength grade of angle steel generally adopts Q235 level, the compressive strength design load of angle steel is known, beam-column's linear stiffness ratio through type 3 can be tried to achieve, and the length of beam and section area are obtained by field survey, and the equivalent strength of timber is obtained (table 3) by our research.

Angle steel need meet:

$\frac{1}{l_y}+\frac{6+4\mathrm{\β}}{l_1}\≤\frac{2f_y{S}_y}{fSh}$ Formula 4

Above formula is changed, obtains the section area S of angle steel _ythe formula 5 of demand fulfillment:

$S_y\≥\frac{fSR}{2f_y}(\frac{1}{l_y}+\frac{6+4\mathrm{\β}}{l_1})$ Formula 5

Above in two formulas, S is the section area of beam, and R is depth of section (when cross section is rectangle) or the diameter (cross section is for time circular) of beam, and β is the line stiffness ratio of beam and column, f _yfor angle steel compressive strength design load, l ₁for the length of beam, f is the equivalent strength of timber, and value is scope is [4.1,7.2], more concrete can see table 3:

Table 3 timber equivalent strength f (N/mm ²)

Thus, as long as the length l of the angle steel determined _y(not comprising the length of tab portions), the minimum cross-sectional area S of the angle steel of requirement can be met according to formula 5 _y.

Find through research, under normal conditions, the length l of angle steel _y? time in times beam span, (span is l is beam span), both economical, intensity meets the requirements, and does not take too large usage space.Beam span obtains by actual measurement.

In order to enable angle steel have better functional performance, angle steel also should meet the requirement of stability, namely meets following formula 9:

$13.5\frac{b_y}{t_y}+{\left(\frac{l_y}{b_y}\right)}^2\·\frac{t_y}{b_y}\≤170$ Formula 9

In formula 9, b _yfor angle steel width, t _yfor angle steel thickness, l _yfor angle steel length.

Through type 5 tries to achieve angle cross section area, according to area inquiry angle steel table, can find out and meet b in formula 9 _yand t _yangle steel.

By step above, we can determine angle steel according to the actual objective parameter of beam, post, by the angle steel of this specification, reinforce knaur point, effectively can improve the bulk strength in node and house.The schematic diagram reinforced as shown in Figure 4.

In order to make overall procedure more science and refinement, this programme also comprises step 4:

Step 4, determine self-tapping screw number:

Actual in conjunction with reinforcing, find the computation model of the node after reinforcing as shown in Figure 4, angle steel mainly bears pressure, and what the self-tapping screw be namely connected with beam column mainly bore is shearing.For the sake of security, we suppose that all vertical forces on beam (the maximum vertical power can born according to beam calculates) are all born by self-tapping screw, and namely do not consider the shear resistance of tenon, the power acted on self-tapping screw is aware of.Self-tapping screw model (the f selecting a kind of locality comparatively to commonly use ₁and r ₁can determine), just can obtain the number of required self-tapping screw:

Formula 6 is utilized to calculate the use number n of self-tapping screw:

$n=\frac{f_{v}S}{f_1{{\mathrm{\πr}}_1}^2}$ Formula 6

In formula 6, f _vfor the shear strength design load of beam timber used, S is the section area of beam, f ₁for the shear strength design load of self-tapping screw, r ₁for the radius of self-tapping screw.

The length of angle steel wing plate can also be determined by step 5:

Step 5, determine angle steel wing plate length:

Be 3d by the minimum range between the known screw of specification and screw ₀, ultimate range is 16d ₀, screw is 2d apart from Member Lip minimum range ₀, ultimate range is 4d ₀.

Wing plate can be rectangle or arc, thus the row of self-tapping screw on wing plate width, n ₁meet formula 8:

$\frac{b_y-8d_0}{16d_0}\≤n_1\≤\frac{b_y-4d_0}{3d_0}$ Formula 8

In formula 8, b _yfor wing plate width, d ₀for the diameter of self-tapping screw; Thus, the row of the self-tapping screw on wing plate length direction can be obtained adopt and round into a method.Thus, the wing plate length l of known angle steel _cspan be:

(3n ₂+ 1) d ₀≤ l _c≤ (16n ₂-8) d ₀formula 7

Angle steel should select the angle steel with wing plate, and namely the two ends of angle steel have bending part to be conveniently connected with beam, pillar; (as shown in Figure 5, the perforate number in figure should according to calculating), and the angle between wing plate and angle steel is all 135 degree, the length of mid portion and the length of two head part are by calculating.The seam application electric welding machine of angle steel and tab portions welds, and the strength grade of weld seam should not be less than the strength grade of angle steel.

This structure of angle steel, oneself can process at the construction field (site), electric welding also can be allowed to spread and process.During construction, first should find the place of angle steel and beam-to-column joint than angle steel, get off with pencil mark, with saw and chisel, the place of angle steel and beam-to-column joint be evened out, angle steel and beam column can better be coupled together by screw.The angle steel set up should be arranged on the middle position of bean column node as far as possible, therefore can first measure with a yardstick out when angle steel is positioned at middle, the position of hole on beam column, mark gets off.Then, according to the mark on beam column, angle steel self-tapping screw is fixed (as shown in Figure 6).After angle steel sets, can on angle steel brushing paint anticorrosion, and the local damage that causes of constructing to be repaired.

Operating principle of the present invention is as follows:

During earthquake, destruction of a node main manifestations is out of joint and rolls over the forms such as tenon.By Tenon joint rotation moment of flexure and angle steel, the restraint forces to node provides the rigidity of angle steel reinforced node, angle steel passes through self-tapping screw securely together with beam-to-column joint, node can be made to keep tight always, allow the frictional force between tenon and the fourth of the twelve Earthly Branches keep larger always, thus when meeting with earthquake, connection stiffness is seldom degenerated and is not even degenerated, and can make the rigidity that node remains higher, simultaneously, the triangle that node and angle steel can form, triangle itself also has rigidity.Therefore, Nodes rigidity is comparatively large, and the distortion of node is less, there will not be phenomenon out of joint.The connection of beam and column is originally just by Tenon node, and now except Tenon node also has angle steel, both can be jointly stressed, and allow the intensity of node herein improve significantly, supporting capacity significantly improves, and prevents node from occurring folding tenon phenomenon.

Application experiment:

The present invention is used for building field, can promote the use of in vast rural area Existing reinforced concrete bridge seismic hardening transformation.

For verifying effect of the present invention, inventor has carried out building model shaketalle test in 2014 in Xi'an University of Architecture and Technology's structural seismic laboratory, utilizes the bean column node of this method to this wood house model to reinforce.As shown in Figure 7, test is loaded on 9 degree of earthquakes of setting up defences, and building model does not collapse, and node does not destroy in experiment.

Experimental result shows:

(1) for rural area wooden construction structural building, when adopting above measure, the supporting capacity (compared with before joint reinforcing) that can improve node is more; Meanwhile, rigidity (compared with before joint reinforcing) can be improved more.Can significantly improve the shock resistance in house during large shake, after reinforcing as requested, even if wooden frame structure experience 9 degree is set up defences, during earthquake, node does not also destroy, and even angle steel and node all there is no and deform, and house does not collapse.

(2) adopt joint reinforcing measure of the present invention, the angle steel of use easily obtains and cost is lower, construct simply.

(3) this simple and effective joint reinforcing method is adapted at promoting the use of in earthquake district occurred frequently, rural area, highly seismic region wooden frame structure.

Claims (6)

1. adopt a method for angle steel reinforced wooden construction node, it is characterized in that, the two ends of described angle steel, with wing plate, after following step determination angle steel specification, utilize the wing plate at angle steel two ends to be connected with beam, post by self-tapping screw:

Step one, measure the rotational angle of the node that needs reinforcement, predicate node, the need of reinforcing, as needed reinforcement, performs step 2;

Step 2, determine the line stiffness ratio β of beam and column:

When the cross section of beam/post is circular, Line stiffness i is:

formula 1

When the cross section of beam/post is rectangle, Line stiffness i is:

formula 2

In formula 1 and formula 2, E is the Deflection Modulus of Elasticity of beam/post, and d is the diameter of the circular cross-section of beam/post, and b is the wide of the circular cross-section of beam/post, and h is the height of the circular cross-section of beam/post, and l is the length of beam/post;

Parameter alpha ₁span be [0.90,0.95], parameter alpha ₂span be [0.80,0.95];

The line stiffness ratio β of beam and column is:

formula 3

Step 3, determine the specification of angle steel:

The length l of angle steel _yspan is l is beam span;

The section area S of angle steel _ydemand fulfillment following formula 5:

formula 5

In formula 5, S is the section area of beam, and R is depth of section or the diameter of beam, and β is the line stiffness ratio of beam and column, f _yfor angle steel compressive strength design load, l ₁for the length of beam, f is the equivalent strength of timber, and value is scope is [4.1,7.2].

2. the method adopting angle steel reinforced wooden construction node as claimed in claim 1, it is characterized in that, described described method also comprises step 4:

Step 4, determine self-tapping screw number:

Formula 6 is utilized to calculate the use number n of self-tapping screw:

formula 6

In formula 6, f _vfor the shear strength design load of beam timber used, S is the section area of beam, f ₁for the shear strength design load of self-tapping screw, r ₁for the radius of self-tapping screw.

3. the method adopting angle steel reinforced wooden construction node as claimed in claim 2, it is characterized in that, described method also comprises step 5:

Step 5, determine angle steel wing plate length:

The wing plate length l of angle steel _cspan be:

(3n ₂+ 1) d ₀≤ l _c≤ (16n ₂-8) d ₀formula 7

In formula 7, n ₂for the row of self-tapping screw on wing plate length direction, round;

N ₁for the row of the self-tapping screw on wing plate width, n ₁meet formula 8:

formula 8

In formula 8, b _yfor wing plate width, d ₀for the diameter of self-tapping screw.

4. the method adopting angle steel reinforced wooden construction node as claimed in claim 1, it is characterized in that, when described angle steel specification is determined, angle steel is demand fulfillment also:

formula 9

In formula 9, b _yfor angle steel width, t _yfor angle steel thickness, l _yfor angle steel length.

5. the method adopting angle steel reinforced wooden construction node as claimed in claim 1, it is characterized in that, the angle between the wing plate at described angle steel two ends and angle steel is 135 °.

6. the method adopting angle steel reinforced wooden construction node as claimed in claim 1, is characterized in that, in described step one, predicate node the need of the concrete grammar reinforced is:

When the rotational angle of dovetail node is not less than 0.05rad, this node needs reinforcement;

When the rotational angle of straight tenon node is not less than 0.04rad, this node needs reinforcement.