CN102912895B - High-ductility coupled shear wall - Google Patents

Abstract

The invention discloses a high ductility coupled shear wall. Compared with the conventional combined shear wall, the joint shear wall is characterized in that: the connecting beam of the combined shear wall of the present invention is a prefabricated cross-type diagonal inclined reinforcement connecting beam, and the filling of the plastic hinge area The material is high ductility fiber concrete; compared with the conventional connecting beam with small span-to-height ratio, the cross-type diagonally-reinforced connecting beam is characterized in that the connecting beam is provided with diagonally inclined reinforcement, and the diagonally inclined reinforcement has no tension Reinforced, and its filling material is high ductility fiber concrete. The base of the connecting beam in the combined shear wall is made of high ductility fiber concrete, and the diagonal reinforcement does not need to be equipped with tie bars, which reduces the amount of steel bars on the premise of ensuring the seismic performance of the connecting beams, and reduces the construction difficulties caused by crowded steel bars , and the coupling beam is prefabricated, which shortens the construction period of the combined shear wall; the base material of the plastic hinge area of the shear wall limb and the coupling beam base material are made of high ductility fiber concrete, which can fully guarantee the overall seismic performance of the combined shear wall .

Description

A High Ductility Coupled Shear Wall

technical field

The invention relates to a shear wall, in particular to a high ductility coupled shear wall which uses high ductility fiber concrete as a filling material and a small span-to-height ratio cross-type diagonally inclined reinforcement coupling beam as a coupling beam.

Background technique

Shear walls, also known as wind-resistant walls or earthquake-resistant walls, structural walls, use reinforced concrete wall panels to replace beams and columns in frame structures, and can bear internal forces caused by various loads, mainly bearing horizontal loads caused by wind loads or earthquakes of the wall. Due to the functional requirements of the structure, it is sometimes necessary to open door and window openings in the shear wall. According to the presence, size, shape and location of openings, shear walls can be divided into full section walls, integral small opening walls, combined limb walls and wall frames. When the shear wall has no opening, or although there is an opening, but the influence of the opening can be ignored, this type of wall is called a full-section wall; when the opening of the shear wall is slightly larger, the impact of the opening on the shear wall is still small , this type of wall is called the overall small opening wall; when the shear wall has one or more rows of large openings along the vertical direction, the section deformation of the shear wall no longer conforms to the assumption of the plane section, and can be regarded as a wall formed by the wall. The horizontal force is jointly resisted by the force couple composed of the bending resistance of each wall and the axial force of the wall. This type of wall is called a combined shear wall; when the openings of the shear walls are arranged in a row When the opening is wide and the width of the wall is relatively small, and the stiffness of the connecting beam is close to or greater than that of the wall, the mechanical performance of the shear wall is similar to that of the frame structure. This type of shear wall is called a wall frame .

The existing combined shear wall design has the following problems: 1) Since the span of the connecting beam in the combined shear wall is not large, but in order to satisfy the rigidity of the connecting beam to ensure the integrity of the combined shear wall, the The lateral movement of the shear wall under the horizontal load is not too large, and the cross-sectional height of the connecting beam cannot be too small, so the span-to-height ratio of the connecting beam is generally small (less than 2.5). High-ratio coupling beams (as shown in Figure 1, conventional small-span-to-height ratio coupling beams include longitudinal bars 2, stirrups 3 outside of longitudinal bars 2, and ordinary concrete filling materials) have been unable to avoid their own premature shear failure , which cannot meet the requirements of the structure for its seismic performance. In order to improve the seismic performance of coupling beams with small span-to-height ratios, the prior art mainly improves them from three aspects: reinforcement scheme, section form and matrix material of coupling beams. In terms of reinforcement scheme and section form improvement, there are mainly cross hidden column reinforced connecting beams, diamond reinforced connecting beams, double connecting beams and steel fiber connecting beams, etc. Among them, the intersecting concealed column reinforced connecting beam (as shown in Figure 2, the intersecting concealed column reinforced connecting beam includes the longitudinal reinforcement 2, the stirrup 3 arranged outside the longitudinal reinforcement 2 and the stirrup arranged between the longitudinal reinforcement 2 The intersecting concealed column 6 and the concealed column stirrup 7 arranged on the intersecting concealed column can meet the requirements of the overall structure on the seismic performance of the small span-to-height ratio coupling beam, and have better shear resistance and energy dissipation capacity. But because it is equipped with intersecting concealed columns 1, a large number of stirrups 2 are arranged on each concealed column, resulting in the large amount of steel used for this type of connecting beam, and the congestion of reinforcing bars causes construction difficulties. In addition, the high ductility concrete coupling beam disclosed in ZL201120109680.2 is based on the structure of ordinary frame beams, and the base material is high ductility concrete, which improves the ductility and energy dissipation capacity of the coupling beam with small span-to-height ratio to a certain extent; If the height ratio is too small (less than 2.5), its ductility no longer meets the seismic requirements of the structure, and the configuration of stirrups needs to be further increased.

2) The elastoplastic properties of combined shear wall piers, such as stiffness, strength, ductility and energy dissipation, etc., mainly depend on their plastic hinge area (the bottom of the wall piers). However, due to the brittle failure mechanism and deformation mode of concrete, it is difficult to ensure the seismic and shear resistance of the plastic hinge area of the shear wall in the design, such as concrete crushing of edge members, oblique tension and baroclinic failure caused by shear force, and failure along construction joints. Slip shear failure, buckling of stressed steel bars, etc.

Contents of the invention

The object of the present invention is to provide a combined shear wall with easy construction, high ductility and good seismic performance.

For this reason, the integrated shear wall provided by the present invention is characterized in that compared with the conventional integrated shear wall: the connecting beam of the integrated shear wall of the present invention is a prefabricated cross-type diagonal inclined reinforcement connecting beam, and The filling material in the plastic hinge area is high ductility fiber concrete; compared with the conventional conventional small-span-height ratio connecting beam, the cross-type diagonally-reinforced connecting beam is characterized in that diagonal longitudinal reinforcements are provided with diagonal Diagonal reinforcement, and its filling material is high ductility fiber concrete.

The configuration of the above-mentioned diagonal bars shall meet the following conditions:

V _wb ≤0.14f _c bh ₀ +1.3f _t bh ₀ +0.24A _sd f _sd sinα (Formula 1)

(Formula 1):

V _wb is the shear bearing capacity of the inclined section of the coupling beam;

b is the width of the connecting beam section;

h ₀ is the effective height of the coupling beam section;

f _c is the compressive strength of high ductility fiber reinforced concrete;

f _t is the axial tensile strength of high ductility fiber reinforced concrete, f _t = 3.683f _c ^0.174 ;

A _sd is the area of unidirectional diagonal reinforcement;

f _sd is the yield strength of diagonal bars;

α is the angle between the diagonal reinforcement and the longitudinal axis of the coupling beam, α=arctan(l _n /h), l _n is the clear span of the coupling beam.

The components of the above-mentioned high ductility fiber concrete are cement, fly ash, silica fume, sand, PVA fiber and water, wherein, in terms of mass percentage, cement: fly ash: silica fume: sand: water = 1:0.9:0.1 : 0.76: 0.58; Based on the total volume of cement, fly ash, silica fume, sand and water mixed uniformly, the volume content of PVA fiber is 1.5%.

The above ^- mentioned cement is PO52.5R Portland cement; the above-mentioned fly ash is Class I fly ash; The maximum particle size of the sand is 1.26 mm; the above-mentioned PVA fiber has a length of 6-12 mm, a diameter of 26 μm or more, a tensile strength of 1200 MPa or more, and an elastic modulus of 30 GPa or more.

The joint shear wall provided by the present invention has the following characteristics:

(1) Less shearing stirrups are used, steel materials are saved, and construction difficulty is reduced.

(2) Using high-ductility fiber concrete as the filling material for the plastic hinge area of the connecting beam and the wall can reduce the overall self-weight of the wall, and the high-ductility fiber concrete has good plastic deformation capacity, and the protective layer concrete will not be damaged when the structure is damaged. Peeling can reduce or even eliminate the repair costs after strong earthquakes.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Figure 1 is a schematic structural view of a conventional small-span-to-height ratio coupling beam;

Fig. 2 is the structural schematic diagram of intersecting concealed column type reinforced connecting beam;

Fig. 3 is the structural representation of the high ductility coupled shear wall of the present invention;

Fig. 4 is the structural representation of cross-type diagonally inclined bar connecting beam of the present invention;

Fig. 5 is A-A sectional view of Fig. 4;

Fig. 6 is the calculation diagram of the nonlinear force-displacement theoretical model;

Figure 7 is a schematic diagram of the size and reinforcement of the R/C specimen and the R/FRC specimen;

Figure 8(a) is a schematic diagram of the failure form of the R/C specimen;

Figure 8(b) is a schematic diagram of the failure morphology of the R/FRC specimen;

Figure 9(a) is the hysteresis curve of the R/C specimen;

Figure 9(b) is the hysteresis curve of the R/FRC specimen;

Figure 10 is the load-displacement skeleton curves of specimen CB-1 and specimen CB-2.

Detailed ways

High ductility fiber concrete is a cement-based composite material in which randomly distributed short fibers are added to the cement matrix and designed through the interface. The fiber types include steel fibers, carbon fibers, and polymer fibers. It has a great ability to absorb energy, and the biggest difference from ordinary fiber concrete is that only about 2% of fibers are added, and its uniaxial tensile strain can reach 3%, and quasi-strain hardening occurs when stretched. There is a good coordinated deformation ability between ductile high-performance concrete and steel bars, and the bond-slip deformation of steel bars is small. The existing technology shows that every ton of cement clinker produced will emit about 1 ton of CO ₂ and other harmful gases, and ductile high-performance concrete uses industrial waste (fly ash) to replace part of the cement clinker (about 50% to 70%), reducing the Emission of harmful gases. The interface design of ductile high-performance concrete does not contain coarse aggregate, which can alleviate the current situation that my country's natural aggregate resources tend to be exhausted.

The present invention combines the advantages of high-ductility fiber concrete structure, and simultaneously considers the configuration of steel bars in coupling beams and the structural requirements of the plastic hinge area in combined-shear walls. The technical solution obtained by making improvements.

With reference to Fig. 3 to Fig. 5, the combined limb shear wall of the present invention comprises wall limb 1 and the connecting beam 8 that is arranged between wall limb 1, and the bottom of wall limb 1 is provided with plastic hinge area 9; Said connecting beam 8 is prefabricated The cross-type diagonally-reinforced connecting beam, the filling material of the plastic hinge area 9 is high ductility fiber concrete (FRC); The stirrups 3 and the diagonal diagonal bars 4 arranged between the diagonal longitudinal bars 2 and the filling material high ductility fiber concrete (FRC) 5 .

The components of the high ductility fiber concrete used are cement, fly ash, silica fume, sand, PVA fiber and water, wherein, in terms of mass percentage, cement: fly ash: silica fume: sand: water = 1:0.9: 0.1:0.76:0.58; based on the total volume of cement, fly ash, silica fume, sand and water mixed uniformly, the volume content of PVA fiber is 1.5%. The optimized materials are: the cement is PO52.5R Portland cement; the above-mentioned fly ash is Class I fly ash; the loss on ignition of the above-mentioned silica fume is less than 6%, the silica content is more than 85%, and the specific surface area Greater than 15000m ² /kg; the maximum particle size of the above sand is 1.26mm; the length of the above PVA fiber is 6-12mm, the diameter is 26μm or more, the tensile strength is 1200MPa or more, and the elastic modulus is 30GPa or more. In addition, a polycarboxylate water reducer with a water reducing rate of more than 30% can be added to the high ductility fiber concrete, and the amount of the water reducer added is 0.8% of the total mass of fly ash, silica fume and cement.

The longitudinal reinforcement 2 and the diagonal reinforcement 4 of the prefabricated cross-type diagonally inclined connecting beam should extend into the shear wall when the wall is poured, and the length of the extension is determined by the diameter of the steel bar. The length a of limb 1 is the greater value of the thickness of the wall limb and 1/4 of the beam height.

The reinforcement method of the above-mentioned cross-type diagonal diagonally reinforced connecting beam is as follows:

Firstly, the dimensions of the coupling beam components are determined according to the structural design requirements, including: coupling beam length /, coupling beam section width b, and coupling beam section effective height h ₀ ;

Then configure the longitudinal reinforcement and stirrup of the coupling beam according to the requirements of the concrete structure design specification (GB 50010-2010);

Then configure diagonal diagonal reinforcement according to the requirements of (Formula 1), where the shear bearing capacity V _wb of the oblique section of the coupling beam should meet the requirements of (Formula 1):

V _wb ≤0.14f _c bh ₀ +1.3f _t bh ₀ +0.24A _sd f _sd sinα (Formula 1)

(Formula 1):

f _c is the compressive strength of high ductility fiber reinforced concrete;

f _t is the axial tensile strength of high ductility fiber reinforced concrete, f _t = 3.683f _c ^0.174 ;

A _sd is the area of unidirectional diagonal reinforcement;

f _sd is the yield strength of diagonal bars;

α is the angle between the diagonal reinforcement and the longitudinal axis of the coupling beam, α=arctan(l _n /h), l _n is the clear span of the coupling beam.

The following is the derivation process of the above (Formula 1) provided by the inventor:

According to the deduction of the compression rod-tie rod theory, referring to Fig. 6, the derivation process only considers the shear resistance of diagonal tendons and FRC.

According to the force balance principle, the beam end shear force V _wb can be obtained as

V _wb ＝(T+C)·sinα (Formula 2)

In (Formula 2), α is the angle between the diagonal reinforcement and the longitudinal axis of the beam, C is the resultant force of the compression bar, T is the resultant force of the tie bar, and:

C＝A′ _sd σ′ _sd +A′ _c σ′ _c (Formula 3)

T＝A _sd σ _sd +A _c σ _c (Formula 4)

(Formula 3):

A′ _sd is the total area of diagonal diagonal reinforcement under unidirectional compression (compression rod), A _sd is the total area of diagonal diagonal reinforcement under unidirectional tension (tie rod), when the reinforcement is symmetrical, A′ _sd =A _sd ;

A _c ′ is the cross-sectional area of the high ductility fiber concrete compression rod (compression rod), A _c is the cross-sectional area of the high ductility fiber concrete tie rod (tie rod), assuming that A _c ′=A _c ;

σ _c ′ is the tensile stress of high ductility fiber concrete, σ _c is the compressive stress of high ductility fiber concrete, and σ′ _sd is the tensile stress of diagonal diagonal bars.

The area A _c ′ of the high ductility fiber reinforced concrete diagonal strut is defined as:

A _c ′=a _s ×b _s (Formula 5)

(Equation 5): a _s is the section height of the high ductility fiber reinforced concrete oblique rod, b _s is the section width of the high ductility fiber reinforced concrete diagonal rod. _s is the cross-sectional width of the coupling beam.

According to the failure mechanism of the diagonally inclined reinforced beam, it is assumed that:

a _s =2x (Formula 6)

(Equation 6): x is the vertical distance between the axes of diagonal oblique bars in one direction (same inclination direction).

The shear capacity V _wb of the oblique section of the high ductility fiber reinforced concrete cross-connected beam with diagonal reinforcement can be considered to be shared by three parts: the high ductility fiber concrete pressure, the high ductility fiber concrete tension and the diagonal reinforcement, namely:

V _wb ＝V _c +V _t +V _sd (Formula 7)

In (Equation 7), the shear force value V _c borne by high ductility fiber reinforced concrete can be expressed as:

V _c ＝ k _c f _c bh ₀ (Formula 8)

In (Equation 8), k _c is the influence coefficient of compressive strength and shear of high ductility fiber reinforced concrete.

According to (Formula 3), V _c can be expressed as:

V _c ＝a _s ×b _s ×σ _c ′×sinα (Formula 9)

Let (Equation 8) and (Equation 9) be equal to get:

$k_c=\frac{a_{\mathrm{the\; s}}\sin \mathrm{\α}}{h_0}$ (Formula 10)

In (Equation 7), the shear force value V _t borne by the high ductility fiber reinforced concrete can be expressed as:

V _t ＝ k _t f _t bh ₀ (Equation 11)

(Equation 11), k _t is the concrete tensile strength and shear influence coefficient;

According to (Equation 4), V _t can be expressed as:

V _t ＝a _s ×b×σ _c sinα (Formula 12)

but

$k_t=\frac{a_{\mathrm{the\; s}}{\mathrm{\σ}}_c\sin \mathrm{\α}}{f_t{h}_0}$ (Formula 13)

In (Equation 7), the shear force value V _sd borne by the diagonal reinforcement can be expressed as:

V _sd ＝ k _sd A _sd f _sd sinα (Formula 14)

(Equation 14), k _sd is the shear influence coefficient of diagonal reinforcement;

According to (Formula 3) and (Formula 4), V _sd can be expressed as:

$V_{\mathrm{sd}}=2A_{\mathrm{sd}}{\mathrm{\σ}}_{\mathrm{sd}}\sin \mathrm{\α}=2A_{\mathrm{sd}}[f_{\mathrm{sd}}+0.01{\mathrm{E.}}_{\mathrm{sd}}({\mathrm{\ϵ}}_c-\frac{f_{\mathrm{sd}}}{{\mathrm{E.}}_{\mathrm{sd}}})]\sin \mathrm{\α}$ (Formula 15)

but,

$k_{\mathrm{sd}}=\frac{2[f_{\mathrm{sd}}+0.01{\mathrm{E.}}_{\mathrm{sd}}({\mathrm{\ϵ}}_c-\frac{f_{\mathrm{sd}}}{{\mathrm{E.}}_{\mathrm{sd}}})]}{f_{\mathrm{sd}}}=0.18+\frac{0.02{\mathrm{E.}}_{\mathrm{sd}}{\mathrm{\ϵ}}_c}{f_{\mathrm{sd}}}$ (Formula 16)

In the above formula, E _sd is the elastic modulus of diagonal diagonal reinforcement, and _εc is the peak strain of FRC under uniaxial compression.

According to the orthogonal test, the inventor designed 42 connecting beam specimens with different reinforcement ratios and span-to-height ratio parameters, and calculated the concrete compressive strength according to (Formula 10), (Formula 13) and (Formula 16). The shear influence coefficient k _c , the concrete tensile strength shear influence coefficient k _t and the oblique reinforcement item shear influence coefficient k _sd are obtained through parameter fitting and taking the lower limit of each parameter to obtain the concrete compressive strength shear influence coefficient k _c , concrete tensile strength shear influence coefficient k _t and oblique bar item shear influence coefficient k _sd are 0.14, 1.3 and 0.24 respectively, and finally (Equation 1) can be obtained.

The construction process of the high ductility coupled shear wall of the present invention is:

Prefabricated Coupling Beams:

(1) Configure the longitudinal reinforcement and stirrup of the coupling beam;

(2) Configure diagonal oblique reinforcement in the connecting beam, and the diagonal oblique reinforcement is fixed on the longitudinal reinforcement and stirrup by wire binding;

(3) Formwork for supporting beams;

(4) Pouring coupling beams;

(5) After 3 days of maintenance, remove the coupling beam formwork;

Pouring the pier:

(1) Configure the vertical distribution of steel bars at the wall piers;

(2) Configure the horizontal distribution of steel bars at the wall piers;

(3) Support wall formwork layer by layer according to the pouring height;

(4) Hoist the prefabricated coupling beam to the corresponding position on one side of the shear wall, and fix it on the formwork of the wall, and the beam end of the coupling beam, the horizontal reinforcement of the coupling beam, and the diagonal diagonal reinforcement of the coupling beam extend into the wall;

(5) Pour the ductile high-performance concrete in the plastic hinge area of the wall pier layer by layer according to the pouring height. The height of the plastic hinge area is selected according to the relevant specifications, and watering is maintained; it is strictly forbidden to beat the steel bars and formwork during the pouring process, and the vibration time must be controlled within 10-20s , to ensure that the vibration is in place and the fibers in the ductile high-performance concrete are intact;

(6) After the ductile high-performance concrete in the plastic hinge area is basically consolidated (1 to 2 days), ordinary concrete in other parts of the wall pier shall be poured in layers according to the pouring height, and the pouring layer height shall be taken according to relevant specifications.

The following are the mechanical performance tests and results of the high ductility fiber concrete of the present invention provided by the inventor.

(1) Use a standard test mold of 70.7mm×70.7mm×70.7mm to make a cube test block, and cure it for 60 days according to the standard curing method, and conduct a cube compressive strength test. The test results show that the average compressive strength of the high ductility fiber concrete test block is 65MPa, the test block is unloaded after reaching the peak load and then loaded for the second time, the residual compressive strength can reach 80% of the peak load, and the failure process of the test block has obvious Compressive toughness.

(2) Use a standard test mold of 40mm×40mm×160mm to make a prism bending test piece, and cure it for 60 days according to the standard curing method, and conduct a bending performance test. The test results show that the initial crack strength of the high ductility fiber concrete specimen is 4.8MPa, the bearing capacity continues to increase after the specimen cracks, and the ultimate strength is 10.1MPa, and the bearing capacity decreases slowly after reaching the peak load. Toughness coefficient The flexural toughness I ₅ , I ₁₀ , I ₂₀ , and I ₃₀ are 6.2, 14.5, 33.0, and 50.6, respectively, indicating high flexural toughness.

(3) Use a test mold of 50mm×15mm×350mm to make a tensile test block, and perform a direct tensile test after curing for 60 days according to the standard curing method. The results show that the average uniaxial tensile strength of high ductility fiber reinforced concrete specimens is 3.6MPa, and the ultimate tensile strain can reach 1.2%. More than 10 cracks.

The above tests show that the ultimate tensile strain of high ductility fiber concrete is much higher than the ultimate tensile strain of ordinary concrete in the "Code for Design of Concrete Structures" GB50010, and the high ductility fiber concrete has higher toughness when it is damaged under compression, tension or bending. , and its failure characteristics are significantly different from those of ordinary concrete that undergo brittle failure.

The above-mentioned mechanical characteristics of the high ductility fiber concrete of the present invention show that it can significantly enhance the compressive bearing capacity and deformation capacity of the joint shear wall as the filling material of the connecting beam and the plastic hinge area, and it is not suitable for brittle failure to reduce or avoid structural damage. post-earthquake repair work.

The following is a comparative test on the seismic performance of the cross-type diagonally inclined reinforced connecting beam (R/FRC specimen) of the present invention and the ordinary concrete diagonally inclined reinforced connecting beam (R/C specimen) provided by the inventor:

(1) Test plan

A total of two specimens were made, the cross-sectional size and reinforcement of the specimens were exactly the same, and the matrix materials were ordinary concrete (R/C specimen) and high-ductility fiber reinforced concrete FRC (R/FRC specimen); the cross-sectional dimensions of the specimens were 600×110mm; the span-to-height ratio is 1; the upper and lower longitudinal reinforcement bars are respectively The longitudinal structural reinforcement on one side of the section is Diagonal bars along one direction are In order to verify the contribution of FRC and cross diagonal diagonal reinforcement to the seismic performance of the coupling beam, the stirrup of the coupling beam is Ф8150, and the stirrup ratio is far less than the code requirement. The section size and reinforcement are shown in Figure 6. When making R/FRC specimens, the coupling beams are prefabricated, that is, the coupling beams are poured first, and the upper and lower end blocks for simulating the wall piers are poured after 7 days. ).

(2) Test results

Figures 8 and 9 show the pseudo-static test results of ordinary concrete diagonally inclined reinforced beams (R/C specimens) and high ductility fiber reinforced concrete crossed diagonally inclined reinforced beams (R/FRC specimens). It can be seen from Figure 8 that when the R/C specimen is damaged, the concrete at the intersection of the "X"-shaped oblique cracks of the coupling beam peels off, while the protective layer of the R/FRC specimen does not fall off. It can be seen from Fig. 9 that the R/C specimen quickly lost its bearing capacity after partial buckling of the oblique reinforcement, while the R/FRC specimen, due to the bridging effect of the fibers, still maintained its bearing capacity after local compression of the oblique reinforcement. If it continues to improve, the crack development is slower than that of the R/C specimen. After the main inclined crack along the direction of the diagonal reinforcement appears in the coupling beam, it can continue to carry stably, which improves the ductility and energy dissipation capacity of the diagonal reinforcement coupling beam. Using high-performance fiber-reinforced concrete instead of ordinary concrete as the matrix of the diagonally inclined connecting beam can improve the yield load (displacement), peak load (displacement) and maximum displacement of the connecting beam, and the ductility, energy dissipation capacity and energy dissipation of the connecting beam. Potential has been significantly improved. It is verified by experiments that the ductile high-performance concrete diagonally inclined-reinforced connecting beam has superior ductility and energy dissipation capacity, and can replace the function of the oblique reinforcement.

From the above tests, it can be seen that:

(1) When the coupling beam reaches the ultimate load, the cracks in the coupling beam of the present invention are fine and dense, the cracks develop and extend slowly, the crack width is obviously smaller than that of ordinary concrete coupling beams, and the protective layer does not peel off, and the damage tolerance is higher, which can reduce Repair costs after a strong earthquake.

(2) The coupling beam of the present invention can continue to bear after reaching the ultimate load, the stiffness decreases slowly, and the ductility is good; after the ordinary concrete coupling beam reaches the ultimate load, the stiffness suddenly decreases and cannot continue to bear.

The following is a comparative test on the seismic performance of the cross-type diagonal diagonally reinforced connecting beam (specimen CB-2) of the present invention and the ordinary reinforced high ductility fiber concrete connecting beam (specimen CB-1) provided by the inventor.

Coupling beam specimen CB-1 and specimen CB-2 have the same section size, the base material is high ductility fiber concrete, the configuration of stirrups and longitudinal reinforcement is the same, and specimen CB-2 is arranged along the diagonal direction Diagonal bars, specimen CB-1 has no bars. After numerical analysis, the load-displacement curve is shown in Figure 10.

In order to study the energy dissipation capacity of the coupling beam, the energy dissipation values of specimen CB-1 and specimen CB-2 in the elastic-plastic deformation stage are obtained by integral calculation of the load-displacement hysteresis curve, respectively 312400 and 551848kN/mm ² . The results show that the energy dissipation capacity of the coupling beam can be significantly improved by adding diagonal bars to the coupling beam.

After calculation, the displacement ductility coefficient of specimen CB-2 is 3.8, which is significantly greater than the displacement ductility coefficient of CB-1, which is 2.6. It shows that adding diagonal tendons to the coupling beam can significantly improve the ductility of the coupling beam, thereby ensuring the stability of the combined shear wall. High ductility and shock resistance.

Claims (3)

1. A high ductility joint shear wall, comprising wall piers and connecting beams arranged between wall piers, the bottom of said wall piers is provided with a plastic hinge area, it is characterized in that said connecting beams are prefabricated intersecting beams The connecting beam with diagonal oblique reinforcement includes longitudinal reinforcement, stirrup arranged on the longitudinal reinforcement, cross diagonal oblique reinforcement arranged between the longitudinal reinforcement and the filling material of the connecting beam, and the connecting beam The filling material of the beam is high ductility fiber concrete; the filling material of the plastic hinge area is high ductility fiber concrete; The configuration of the diagonal bars should meet the following conditions: V _wb ≤0.14f _c bh ₀ +1.3f _t bh ₀ +0.24A _sd f _sd sinα (Formula 1) (Formula 1): V _wb is the shear bearing capacity of the inclined section of the coupling beam; b is the width of the connecting beam section; h ₀ is the effective height of the coupling beam section; f _c is the compressive strength of high ductility fiber reinforced concrete; f _t is the axial tensile strength of high ductility fiber reinforced concrete, f _t = 3.683f _c ^0.174 ; A _sd is the area of unilateral diagonal reinforcement; f _sd is the yield strength of diagonal reinforcement; α is the angle between the diagonal reinforcement and the longitudinal axis of the coupling beam, α=arctan(l _n /h), l _n is the clear span of the coupling beam, and h is the section height of the coupling beam. 2. The high ductility coupled shear wall as claimed in claim 1, wherein the components of the high ductility fiber concrete are cement, fly ash, silica fume, sand, PVA fiber and water, wherein, according to In terms of mass percentage, cement: fly ash: silica fume: sand: water = 1: 0.9: 0.1: 0.76: 0.58; based on the total volume of cement, fly ash, silica fume, sand and water mixed uniformly, PVA The volume dosage of fibers is 1.5%. 3. The high ductility joint shear wall as claimed in claim 2, wherein said cement is PO52.5R Portland cement; said fly ash is Class I fly ash; said silica fume The loss on ignition is less than 6%, the silica content is greater than 85%, and the specific surface area is greater than 15000m ² /kg; the maximum particle size of the sand is 1.26mm; the length of the above-mentioned PVA fiber is 6-12mm, the diameter is more than 26μm, The tensile strength is 1200 MPa or more, and the elastic modulus is 30 GPa or more.