Precast external eccentrically confined composite column

Abstract

The application relates to the technical field of building engineering, in particular to a prefabricated external ECC jacket combined column, which comprises a column body and a prefabricated ECC jacket mechanism, and the prefabricated ECC jacket mechanism is located in the plastic hinge area of the column body; the prefabricated ECC jacket mechanism comprises multiple jacket single pieces and multiple connecting assemblies, the multiple jacket single pieces are fixed to the outer periphery of the column body in a spaced jacket mode, and the connecting assembly is connected between two adjacent jacket single pieces; the connecting assembly comprises a connecting frame body, a damping piece and a detection piece, the damping piece and the detection piece are installed in the connecting frame body, and the jacket single piece is inserted into the connecting frame body from both ends and fixed therein. The prefabricated ECC jacket and the connecting assembly are cooperated to significantly improve the stress and strain level of the concrete in the column body, and the anti-seismic performance is greatly enhanced, the problem that the traditional reinforcing mode is prone to through cracks is fundamentally solved, and the constraint effect of the jacket structure is ensured to be continuously exerted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building engineering, and in particular to a prefabricated external ECC jacketed composite column. BACKGROUND

[0002] In building frame structures, columns as key load transfer components bear the important function of connecting upper and lower parts, and their performance is directly related to the safety and use efficiency of the overall structure. In order to improve the seismic toughness of column components, the engineering community has widely studied the application of ultra-high performance engineered cementitious composites (ECC), and the jacket reinforcement technology is one of the main forms.

[0003] However, the existing ECC jacket reinforcement scheme usually only wraps ECC material as an outer layer on the outside of the ordinary concrete column, which has obvious limitations: first, under the action of load, vertical through cracks or local buckling failure may occur prematurely, resulting in premature failure of the reinforced layer; second, the reinforcement method solely relying on the performance of ECC material has limited improvement on the seismic performance of the column, and the ECC material has strict requirements on maintenance conditions and molding process, which is not conducive to large-scale engineering promotion. These problems seriously restrict the practical application of ECC jacket technology. SUMMARY

[0004] The present application aims to provide a prefabricated external ECC jacketed composite column to solve the technical problems that the structural column with an ECC jacket in the prior art is prone to premature vertical through cracks or local buckling failure under load and has limited seismic performance improvement, and the specific technical solutions are as follows:

[0005] The present application provides a prefabricated external ECC jacketed composite column, which comprises a column body and a prefabricated ECC jacket mechanism, and the prefabricated ECC jacket mechanism is located in the plastic hinge region of the column body.

[0006] The prefabricated ECC jacket mechanism comprises a plurality of jacket single pieces and a plurality of connecting components, the plurality of jacket single pieces are fixed to the outer periphery of the column body in a spaced jacketed manner, and the connecting component is connected between adjacent two jacket single pieces.

[0007] The connecting component comprises a connecting frame body, a damping piece and a detection piece, the damping piece and the detection piece are installed inside the connecting frame body, and the jacket single piece is inserted and fixed into the connecting frame body from both ends.

[0008] Further improvement of the prefabricated external ECC jacketed composite column of the present application is that the cross section of the connecting frame body is H-shaped, a receiving chamber is formed in the middle part of the connecting frame body, and the damping piece and the detection piece are installed in the receiving chamber.

[0009] The further improvement of the prefabricated external ECC jacketed composite column of the present application is that the connecting frame body comprises an inner ring-shaped plate, an outer L-shaped plate and an outer T-shaped plate, the inner ring-shaped plate is sleeved and fixed to the outer periphery of the column body;

[0010] The outer L-shaped plate is fixed to the inner ring-shaped plate, and a first space for inserting and installing the jacket single piece is formed between the outer L-shaped plate and the lower part of the inner ring-shaped plate;

[0011] The outer T-shaped plate is fixed to the inner ring-shaped plate, and a second space for inserting and installing the jacket single piece is formed between the outer T-shaped plate and the upper part of the inner ring-shaped plate, and the accommodation cavity is formed between the outer T-shaped plate and the middle part of the inner ring-shaped plate.

[0012] The further improvement of the prefabricated external ECC jacketed composite column of the present application is that the outer side of the turning part of the outer L-shaped plate is fixed with a ring-shaped U-shaped plate, the lower flange plate of the outer T-shaped plate is inserted into the ring-shaped U-shaped plate, and the end of the lower flange plate of the outer T-shaped plate has a gap with the bottom wall of the ring-shaped U-shaped plate.

[0013] The further improvement of the prefabricated external ECC jacketed composite column of the present application is that the damping member is a spring, the stiffness coefficient of the spring is calculated by the following formula:

[0014] ;

[0015] ;

[0016] wherein, ω is the predominant frequency of the earthquake, T is the characteristic period of the earthquake; M is the mass of the upper jacket single piece of the damping spring and the outer T-shaped plate; the pre-pressing amount of the spring under different seismic fortification intensities β is calculated by the following formula:

[0017] ;

[0018] wherein, g is the acceleration of gravity.

[0019] The further improvement of the prefabricated external ECC jacketed composite column of the present application is that the number of the jacket single pieces is three, the three jacket single pieces are arranged at intervals along the length direction of the column body, the height of the bottom jacket single piece :

[0020] ;

[0021] wherein, H is the height of the column, f is the tensile strength of the longitudinal reinforcement, Diameter of longitudinal reinforcement

[0022] Height of middle jacket unit Height of top jacket unit Respectively:

[0023] ;

[0024] ;

[0025] Wherein, Width of column section.

[0026] The further improvement of the prefabricated external ECC jacket combined column of the application is that the detection member between the bottom jacket unit and the middle jacket unit is a displacement sensor, and the displacement sensor is provided with a first alarm.

[0027] The further improvement of the prefabricated external ECC jacket combined column of the application is that the detection member between the middle jacket unit and the top jacket unit is an acceleration sensor, and the acceleration sensor is provided with a second alarm.

[0028] The technical scheme of the application has the following beneficial effects:

[0029] The prefabricated external ECC jacket combined column of the application significantly improves the stress and strain level of the concrete in the column body through the synergistic effect of the prefabricated ECC jacket and the column body, and further greatly enhances the seismic performance. The multi-section ECC jacket design fundamentally solves the problem of the easy occurrence of penetrating cracks in the traditional reinforcement mode, ensures the continuous constraint effect of the jacket structure, and solves the technical problems of the structural column provided with the ECC jacket in the prior art, such as the easy occurrence of vertical penetrating cracks or local buckling damage under the action of load and the low seismic performance. The prefabricated component form of the application effectively avoids the construction difficulty of high maintenance and molding requirements of ECC material on site, the structure of the connecting assembly can effectively absorb and dissipate most of the buckling deformation that the ECC jacket may bear, prevent local damage failure, and at the same time significantly reduce the risk of large cracks of the ECC jacket under the action of earthquake, and maintain the continuous constraint effect of the ECC jacket on the core concrete.

[0030] In addition to the purposes, features and advantages described above, the application has other purposes, features and advantages. The application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, illustrate the preferred embodiments of the application and assist in the explanation of the application. In the drawings:

[0032] Figure 1 is a sectional view of the prefabricated external ECC jacketed composite column of the present application at the position of the connecting assembly;

[0033] Figure 2 is a sectional view of the prefabricated external ECC jacketed composite column of the present application at the position of the jacket single piece;

[0034] Figure 3 is Figure 1 schematic view along the section A-A;

[0035] Figure 4 is Figure 1 schematic view along the section B-B;

[0036] Figure 5 is Figure 3 enlarged view of the connecting assembly area;

[0037] Figure 6 is Figure 4 enlarged view of the connecting assembly area.

[0038] wherein 1, column body; 2, prefabricated ECC jacket mechanism; 21, bottom jacket single piece; 22, middle jacket single piece; 23, top jacket single piece; 3, spring; 4, detection piece; 41, displacement sensor; 42, acceleration sensor; 5, connecting frame body; 51, inner side ring-shaped plate; 52, outer side L-shaped plate; 53, outer side T-shaped plate; 6, ring-shaped U-shaped plate; 7, longitudinal steel bar; 8, stirrup; 9, one layer of plane. DETAILED DESCRIPTION

[0039] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0040] Referring to Figures 1-6 shown, a prefabricated external ECC jacketed composite column comprises a column body 1 and a prefabricated ECC jacket mechanism 2, which is located in the plastic hinge area of the column body 1;

[0041] The prefabricated ECC jacket mechanism 2 comprises a plurality of jacket single pieces and a plurality of connecting assemblies, the plurality of jacket single pieces are fixed to the outer periphery of the column body 1 in a spaced jacketing manner, and the connecting assembly is connected between adjacent two jacket single pieces;

[0042] The connecting assembly comprises a connecting frame body 5, a damping piece and a detection piece 4, the damping piece and the detection piece 4 are installed inside the connecting frame body 5, and the jacket single piece is inserted and fixed into the connecting frame body 5 from both ends.

[0043] Specifically, column 1 is a cast-in-place reinforced concrete structure, with longitudinal reinforcing bars 7 and stirrups 8 inside. The entire precast ECC jacket mechanism 2 is manufactured and installed in the factory. During on-site construction, grooves for installing the precast ECC jacket mechanism 2 are left on the first-floor plane 9 or other locations. The precast ECC jacket mechanism 2 is inserted into the grooves and fixed with structural adhesive. Finally, concrete is poured on-site inside the precast ECC jacket mechanism 2 to form column 1. The jacket is precast using ECC material, and the compressive strength of the ECC material should be approximately 1.2 to 2 times that of ordinary concrete, and should not exceed 3 times.

[0044] Preferred, such as Figures 3-6 As shown, the cross-section of the connecting frame 5 is H-shaped, and a receiving chamber is formed in the middle of the connecting frame 5. The damping component and the detection component 4 are installed in the receiving chamber. The outside of the receiving chamber is not sealed to buffer the deformation of the column 1 during an earthquake. The entire connecting frame 5 is made of steel plate to improve the overall strength of the prefabricated external ECC jacketed composite column. Q235B steel can be used when the seismic resistance requirements are relatively low, and Q335B steel can be used when the seismic resistance requirements are high. Welding of the steel should avoid welding fatigue. Butt welding can be used, and a smooth weld shape should be adopted to avoid sharp notches.

[0045] Preferably, the connecting frame 5 includes an inner ring plate 51, an outer L-shaped plate 52, and an outer T-shaped plate 53. The inner ring plate 51 is fitted and fixed to the outer periphery of the column 1. The inner surface of the inner ring plate 51 is connected to the cast-in-place concrete column 1, and the outer surface is connected to the single jacket piece. The surface of the inner ring plate 51 is roughened to enhance the bonding stress with the cement-based material. The thickness of the inner ring plate 51 is 1 cm, the outer diameter is the diameter of the column 1, and the height is 15~25 cm.

[0046] The outer L-shaped plate 52 is fixed to the inner annular plate 51, and a first space is formed between the lower part of the outer L-shaped plate 52 and the inner annular plate 51 for the insertion and installation of the jacket single piece; the short side length of the outer L-shaped plate 52 is the thickness of the jacket single piece, the long side length is about 7cm, and the short side needs to be welded to the inner annular plate 51; the outer L-shaped plate 52 is located on the outside of the jacket single piece, and its inner surface needs to be roughened to increase the bonding stress with the ECC jacket; the outer L-shaped plate 52 forms a groove structure with the inner annular plate 51 by welding to increase the connection with the jacket single piece.

[0047] The outer T-shaped plate 53 is fixed to the inner ring-shaped plate 51, and a second space for inserting and mounting the jacket single piece is formed between the outer T-shaped plate 53 and the upper part of the inner ring-shaped plate 51, and the accommodating cavity is formed between the outer T-shaped plate 53 and the middle part of the inner ring-shaped plate 51. The thickness of the entire connecting frame body 5 is 1 cm. The length of the web of the outer T-shaped plate 53 is the thickness of the jacket single piece, and the lengths of the two side flanges are not equal, one being 8 cm long and the other being 4 cm long; the bottom end of the web of the outer T-shaped plate 53 is welded to the inner ring-shaped plate 51, and the inner surface thereof is roughened to increase the bonding stress with the jacket single piece, and the outer T-shaped plate 53 is welded to the inner ring-shaped plate 51 to form a groove structure to increase the connection with the jacket single piece.

[0048] Preferably, the outer side of the turning part of the outer L-shaped plate 52 is fixed with a ring-shaped U-shaped plate 6, the lower flange plate of the outer T-shaped plate 53 is inserted into the ring-shaped U-shaped plate 6, and the end of the lower flange plate of the outer T-shaped plate 53 has a gap with the bottom wall of the ring-shaped U-shaped plate 6. Specifically, the shorter side flange plate of the outer T-shaped plate 53 is inserted into the channel steel groove with an insertion depth of about 2 cm. The thickness of the ring-shaped U-shaped plate 6 is 0.5 cm, and the height of the gap is about 2.5 cm for buffering the deformation of the column 1 when an earthquake occurs.

[0049] Preferably, the damping member is a spring 3, which is located in the accommodating space formed by the inner ring-shaped plate 51, the outer L-shaped plate 52, and the outer T-shaped plate 53. In this embodiment, the net height of the accommodating space is about 5 cm, as shown in Figure 1 , there are 20 damping springs 3 in the accommodating space, which are uniformly distributed in the closed area, and the two ends of the spring 3 are connected with the two ends of the outer L-shaped plate 52 and the outer T-shaped plate 53, respectively.

[0050] The spring 3 needs to be set with a suitable stiffness coefficient and pre-pressing amount according to the seismic fortification intensity of the project site. The stiffness coefficient needs to be considered according to the seismic fortification intensity. When an earthquake occurs, the predominant frequency of the earthquake is .

[0051] ;

[0052] The spring 3 is designed according to the rigid structure to reduce the seismic response. The natural frequency of the damping spring 3 is considered to be twice the predominant frequency of the earthquake, and when the damping spring 3 is designed, the stiffness coefficient of the spring 3 is calculated by the following formula:

[0053] ;

[0054] wherein, is the predominant frequency of the earthquake, is the characteristic period of the earthquake.​ Let be the mass of the upper jacket of the shock-absorbing spring 3 and the outer T-shaped plate 53; since springs 3 are connected in parallel in each layer, the stiffness coefficient of a single spring 3 is... k / 20; The preload of the spring 3 is set under different seismic fortification intensities. β Calculate using the following formula:

[0055] ;

[0056] in, This is the acceleration due to gravity.

[0057] Preferred, such as Figure 3 and Figure 4 As shown, there are three individual jacket components, spaced apart along the length of column 1. Each of the three independent jacket components has a different height due to the stress characteristics of column 1 under seismic loads. The bottom jacket component 21 needs to be inserted 10cm below the first-layer plane 9. Its inner side is fixed to the cast-in-place concrete, and its outer side is fixed to the first-layer plane 9 using structural adhesive to improve the integrity of the ECC jacket and the concrete structure. When connecting with structural adhesive, the thickness of the adhesive should be controlled at approximately 3-5mm; too thin an adhesive will affect the bonding strength, while too thick an adhesive will take too long to bond. The height of the bottom jacket component 21... :

[0058] ;

[0059] in, The height of the column. The tensile strength of longitudinal reinforcement 7, The diameter of the longitudinal reinforcement 7;

[0060] The height of the single piece of the central jacket is 22. and the height of the top jacket single piece 23 They are respectively:

[0061] ;

[0062] ;

[0063] in, This represents the width of the column cross-section.

[0064] Three independent external jacket single pieces can avoid the through cracks of the jacket and affect the use efficiency. The inner side of the three jacket single pieces is chiseled to facilitate the close bonding with the cast-in-place concrete column 1. The bottom of the bottom jacket single piece 21 is connected with a layer of plane 9 through structural glue, and the top end is connected with the outer L-shaped plate 52 through structural glue; the upper and lower ends of the middle jacket single piece are connected with the upper outer L-shaped plate 52 and the lower outer T-shaped plate 53 through structural glue; the lower end of the top jacket single piece is connected with the outer T-shaped plate 53 through structural glue. The thickness of the jacket single piece is 50-80mm. In the embodiment, the number of connecting components is two, which are distributed at the two ends of the middle jacket single piece.

[0065] Preferably, the detection member 4 between the bottom jacket single piece 21 and the middle jacket single piece 22 is a displacement sensor 41, and the displacement sensor 41 is provided with a first alarm. The displacement sensor 41 is used for monitoring deformation, and when the displacement deformation reaches 1cm when an earthquake occurs, the internal first alarm will trigger a pre-warning signal, and when the deformation reaches 2cm, an emergency alarm signal will be sent.

[0066] Preferably, the detection member 4 between the middle jacket single piece 22 and the top jacket single piece 23 is an acceleration sensor 42, and the acceleration sensor 42 is provided with a second alarm. The number of displacement sensors 41 and acceleration sensors 42 is four, and one is arranged in the middle of each of the four faces of the column. The acceleration sensor 42 is used for monitoring acceleration, and when the acceleration is 0.1g (g is the acceleration of gravity) when an earthquake occurs, the second alarm sends a pre-warning signal, and when the acceleration is 0.2g, an emergency alarm signal is sent.

[0067] The built-in displacement sensor 41 and acceleration sensor 42 can monitor the deformation of the column 1 in real time, intelligently send a graded pre-warning signal according to the deformation degree, provide reliable guarantee for earthquake emergency response, effectively improve the structural safety protection ability, and effectively protect the safety of personnel and property.

[0068] The prefabricated external ECC jacket combined column of the application significantly improves the stress and strain level of the concrete in the column body 1 through the synergistic effect of the prefabricated ECC jacket and the column body 1, and further greatly enhances the seismic performance. The multi-section ECC jacket design fundamentally solves the problem of the easy occurrence of penetrating cracks in the traditional reinforcement mode, ensures the continuous constraint effect of the jacket structure, and solves the technical problems of the structural column provided with the ECC jacket in the prior art, such as the easy occurrence of vertical penetrating cracks or local buckling damage under the action of load and the low seismic performance. The prefabricated component form of the application effectively avoids the construction difficulty of high maintenance and molding requirements of ECC material on site, the structure of the connecting assembly can effectively absorb and dissipate most of the buckling deformation that the ECC jacket may bear, prevent local damage failure, and at the same time significantly reduce the risk of large cracks in the ECC jacket under the action of earthquake, and maintain the continuous constraint effect of the ECC jacket on the core concrete.

[0069] The finite element analysis results of the comparison of the seismic performance of the prefabricated external ECC jacket combined column of the application and the traditional external ECC jacket combined column are as follows:

[0070] The modeling method of the model used in the comparison process refers to the Concrete Structure Design Standard (GB / T 50010-2010 (2024 edition)), Mander model (used to describe the stress-strain relationship of concrete under transverse steel reinforcement constraint), Clough steel reinforcement constitutive model (used to describe the damage accumulation of steel reinforcement in the process of cyclic loading), etc. The model has been tested and verified, and the error is less than 5%. The specific method is as follows:

[0071] The cross-sectional size of the column component used is 350*350mm, and the column height is 3000mm. The height of the traditional ECC jacket used is 800mm, and the jacket thickness is 50mm, which is simply wrapped around the plastic hinge area at the bottom of the column during implementation. The structure using the application is a three-section ECC jacket, and the sum of the heights of the three-section jacket is 800mm, and the jacket thickness is 50mm. When analyzing the seismic performance, two kinds of constant vertical axial compression ratios are compared, which are axial compression ratios of 0.2 and 0.6, respectively, and the horizontal loading is controlled by displacement. In addition, the increment of each level of horizontal displacement loading is 5mm, and each level of cycle is two cycles, and the loading is stopped until 50mm. Compared with ordinary concrete columns, the following compares the increments of the seismic performance improvement of two different ECC jacket combined columns under two kinds of axial compression ratios, and the specific results are as follows:

[0072]

[0073] It can be known from the comparison of the data that, compared with the traditional external ECC jacket, the anti-seismic performance of the column adopting the external ECC jacket of the application is more obviously improved, especially in the improvement of cumulative energy dissipation, the increment of which is more than one time of the traditional external ECC jacket. It is further illustrated that the multi-section prefabricated external ECC jacket combined column has the prospect of engineering promotion.

[0074] The preferred embodiments of the application have been described above with the aid of drawing. Obviously, the application can be implemented not only in the form of the preferred embodiments, but also in the form of other embodiments. Therefore, the above description is only a preferred embodiment of the application and is not used to limit the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A prefabricated external ECC jacketed composite column, characterized in that, It includes a column (1) and a prefabricated ECC sleeve mechanism (2), the prefabricated ECC sleeve mechanism (2) being located in the plastic hinge region of the column (1); The prefabricated ECC jacket mechanism (2) includes multiple jacket pieces and multiple connecting components. The multiple jacket pieces are spaced apart and fixed to the outer periphery of the column (1). The connecting components are connected between two adjacent jacket pieces. The connecting assembly includes a connecting frame (5), a shock absorber and a detection component (4). The shock absorber and the detection component (4) are installed inside the connecting frame (5). The single jacket is inserted and fixed inside the connecting frame (5) from both ends. The cross-section of the connecting frame (5) is H-shaped, and a receiving chamber is formed in the middle of the connecting frame (5). The shock absorber and the detection component (4) are installed in the receiving chamber. The connecting frame (5) includes an inner ring plate (51), an outer L-shaped plate (52) and an outer T-shaped plate (53), wherein the inner ring plate (51) is sleeved and fixed to the outer periphery of the column (1); The outer L-shaped plate (52) is fixed to the inner ring plate (51), and a first space is formed between the lower part of the outer L-shaped plate (52) and the inner ring plate (51) for inserting and installing the single piece of the jacket. The outer T-shaped plate (53) is fixed on the inner ring plate (51), and a second space for inserting and installing the single piece of the jacket is formed between the upper part of the outer T-shaped plate (53) and the inner ring plate (51), and the receiving chamber is formed between the middle part of the outer T-shaped plate (53) and the inner ring plate (51). The shock absorber is a spring (3), and the stiffness coefficient of the spring (3) is... Calculated by the following formula: ； ； in, For the dominant frequency of earthquakes, The characteristic period of an earthquake; The mass of the upper jacket of the shock-absorbing spring (3) and the outer T-shaped plate (53); the preload of the spring (3) under different seismic fortification intensities. β Calculate using the following formula: ； in, This is the acceleration due to gravity.

2. The prefabricated external ECC jacketed composite column according to claim 1, characterized in that, An annular U-shaped plate (6) is fixed to the outside of the turning point of the outer L-shaped plate (52). The lower flange of the outer T-shaped plate (53) is inserted into the annular U-shaped plate (6), and the end of the lower flange of the outer T-shaped plate (53) has a gap with the bottom wall of the annular U-shaped plate (6).

3. The prefabricated external ECC jacketed composite column according to claim 1, characterized in that, The number of the three jacket pieces is three, and the three jacket pieces are spaced apart along the length of the column (1). The height of the bottom jacket piece (21) is... : ； in, The height of the column. The tensile strength of the longitudinal reinforcement (7) is... The diameter of the longitudinal reinforcement (7); Height of the middle jacket single piece (22) Height of the top jacket unit (23) They are respectively: ； ； in, This represents the width of the column cross-section.

4. The prefabricated external ECC jacketed composite column according to claim 3, characterized in that, The detection element (4) between the bottom jacket piece (21) and the middle jacket piece (22) is a displacement sensor (41), and the displacement sensor (41) is equipped with a first alarm.

5. The prefabricated external ECC jacketed composite column according to claim 3, characterized in that, The detection element (4) between the middle jacket unit (22) and the top jacket unit (23) is an acceleration sensor (42), and the acceleration sensor (42) is equipped with a second alarm.

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