An additional aluminum rib FRP tendon non-magnetic concrete frame structure and non-magnetic concrete

Abstract

The application relates to a magnet-free concrete frame structure with additional aluminum ribs and magnet-free concrete, and the concrete frame structure comprises FRP beam longitudinal reinforcement, additional aluminum ribs, FRP column longitudinal reinforcement and magnet-free concrete; the additional aluminum ribs are respectively anchored at the two ends of the FRP beam longitudinal reinforcement and the top end of the FRP column longitudinal reinforcement, the required anchoring length of the FRP longitudinal reinforcement is effectively reduced, and the FRP beam longitudinal reinforcement and the FRP column longitudinal reinforcement are arranged in the magnet-free concrete without bending. The magnet-free concrete is composed of the following components in parts by weight: 360-500 parts of magnet-free cement, 700-800 parts of magnet-free fine aggregate, 950-1200 parts of magnet-free coarse aggregate, 150-180 parts of water, 0.2-0.4 parts of water reducing agent and 0-0.2 parts of functional additive; the residual magnetism intensity of each component is lower than 1 nT. The FRP longitudinal reinforcement with a residual magnetism intensity of less than 0.2 nT and the magnet-free concrete with a residual magnetism intensity of less than 1 nT are adopted, the interference of the magnetic substances (the residual magnetism reaches thousands or even tens of thousands of nT) in the conventional steel bars and concrete on high-precision equipment and instruments is effectively avoided, the magnetic stability during the service life of the structure is effectively ensured, and strong support is provided for the development and application of frontier scientific research technology.

Description

Technical Field

[0001] The invention relates to the technical field of concrete materials and structures, in particular to a non-magnetic concrete frame structure with additional aluminum ribs and FRP bars and non-magnetic concrete. Background Art

[0002] With the development of science and technology, the construction of extremely weak magnetic infrastructure is imminent. For example, the existing deep space magnetic detectors cannot meet the needs of deep space exploration, and extremely weak magnetic infrastructure is urgently needed as a research and development platform for the new generation of ultra-high sensitivity magnetometers (pT-fT level) and their calibration and testing systems. High-end cardio-cerebral magnetic imaging devices are important equipment for the study of neuroscience and major cardio-cerebral diseases. Their normal operation needs to be carried out in a non-magnetic environment to ensure the accuracy and reliability of the data. In recent years, the country has attached great importance to earthquake monitoring and early warning work, and has taken multiple measures to accelerate the pace of seismic network construction. With the increasing requirements for the accuracy of observation data, the need to improve the anti-magnetic interference capability of non-magnetic seismic stations has become increasingly urgent.

[0003] The construction of extremely weak magnetic infrastructure faces multiple challenges in terms of materials and structural technology. Existing technologies and materials struggle to fully meet the specialized requirements of non-magnetic environments (<1 nT). Conventional concrete has a residual magnetism of hundreds of nT, and currently no low-magnetic concrete can simultaneously meet the required residual magnetism, mechanical properties, and construction performance. Regarding reinforcement, traditional carbon or alloy rebar can cause significant magnetic field interference. The mechanical properties of copper alloy rebar, for example, do not meet the requirements for load-bearing reinforcement in large-scale buildings.

[0004] Fiber reinforced plastic (FRP) is a new type of lightweight, high-strength material with excellent corrosion resistance and mechanical properties, and a residual magnetic intensity of less than 0.2nT. It can be used as a non-magnetic reinforcement material for engineering structures with high requirements for mechanical properties and magnetic control. A large number of studies have been carried out on the use of fiber reinforced plastic as load-bearing reinforcement in ordinary concrete structures, and the relevant theories are relatively mature. However, traditional FRP materials still have significant defects in frame structure applications. FRP materials have low transverse shear strength, weak interfacial bonding with concrete, and require a long anchorage length. The tensile strength of FRP bars decreases significantly after bending and anchoring, making it difficult to effectively anchor FRP bars in the beam-column node area. This problem has not yet been well solved. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the application provides an additional aluminum rib FRP bar non-magnetic concrete frame structure, which comprises FRP beam longitudinal reinforcement, FRP column longitudinal reinforcement, non-magnetic concrete and a plurality of additional aluminum ribs; the additional aluminum ribs are respectively anchored at both ends of the FRP beam longitudinal reinforcement and the top end of the FRP column longitudinal reinforcement, and the FRP beam longitudinal reinforcement and the FRP column longitudinal reinforcement are arranged in the non-magnetic concrete without bending, wherein the FRP beam longitudinal reinforcement and the non-magnetic concrete wrapped outside the FRP beam longitudinal reinforcement form a non-magnetic concrete beam, the FRP column longitudinal reinforcement and the non-magnetic concrete wrapped outside the FRP column longitudinal reinforcement form a non-magnetic concrete column, and the whole forms a concrete frame structure. The FRP beam longitudinal reinforcement and the FRP column longitudinal reinforcement are not limited to one complete FRP bar, and can also be a plurality of FRP bars connected by lapping. The additional aluminum ribs can also be used for the end parts of other FRP bars which need to be anchored.

[0006] The FRP is used as force reinforcement in the non-magnetic concrete, the whole concrete frame structure can be non-magnetic, and the cost is relatively low. The additional aluminum ribs are anchored at both ends of the FRP beam longitudinal reinforcement and the top end of the FRP column longitudinal reinforcement, so that the anchoring performance and the anti-seismic performance at the parts are increased.

[0007] The setting of a single additional aluminum rib can greatly reduce the anchoring length of the FRP bar in the concrete, effectively increase the anchoring performance of the non-magnetic concrete, and prevent the slip or even pull-out of the bar and the concrete under the action of long-term or seismic load. At the same time, since the additional aluminum rib increases the anchoring performance and reduces the anchoring length, the FRP beam longitudinal reinforcement and the FRP column longitudinal reinforcement do not need to be bent and anchored, so that the strength weakening caused by the long anchoring length and the bending and anchoring of the FRP longitudinal reinforcement is avoided. In a limited length, the anchoring performance of the FRP bar in the concrete can be increased without bending and anchoring, so that the key problem of using the FRP bar to form a concrete frame structure is solved.

[0008] Further, a plurality of additional aluminum ribs are anchored at both ends of the FRP beam longitudinal reinforcement and / or the top end of the FRP column longitudinal reinforcement, the residual magnetic strength of the FRP beam longitudinal reinforcement and the FRP column longitudinal reinforcement is lower than 0.2 nT, and the residual magnetic strength of the additional aluminum ribs is lower than 0.5 nT.

[0009] Further, a plurality of FRP stirrups are further included, a plurality of FRP stirrups are arranged in parallel with the FRP beam longitudinal reinforcement and the FRP column longitudinal reinforcement, the FRP stirrups are bound with each FRP beam longitudinal reinforcement and the corresponding FRP column longitudinal reinforcement to form a frame structure FRP reinforcement skeleton, and the residual magnetic strength of the FRP stirrups is lower than 0.2 nT.

[0010] Further, the FRP stirrups are formed by laminating and winding FRP fibers soaked in resin, and the FRP stirrups are formed after curing. The pultruded FRP stirrups are prone to damage at the lapped segments or corner areas, and thus the restraining effect on the concrete is weakened. The wound FRP stirrups are directly made into stirrups with the required shape and size, the full length of a single FRP fiber is not disconnected, the bending part is free of wrinkles and kinks, and the restraining effect of the stirrups can be effectively guaranteed.

[0011] Further, the number of additional aluminum ribs n is selected according to the anchoring length, and the anchoring length of the FRP beam longitudinal reinforcement and / or the FRP column longitudinal reinforcement of the additional aluminum ribs is set as:

[0012]

[0013] wherein L d is the anchoring length, B is a coefficient, f tu is the ultimate tensile strength of the FRP reinforcement, d is the diameter of the FRP reinforcement, f c is the axial compressive strength of the concrete cylinder, i is an equivalent interface enhancement coefficient considering the ratio of the interface strength of the aluminum alloy and FRP to the interface strength of the FRP reinforcement and the concrete, and is linearly related to n, and the specific value is determined according to the experimental data regression;

[0014]

[0015] wherein τ u is the ultimate interfacial bond strength;

[0016]

[0017] wherein A is the cross-sectional area of the FRP reinforcement, L d0 is the anchoring length of the FRP reinforcement without the additional aluminum ribs.

[0018] Further, when the additional aluminum ribs are anchored, the additional aluminum ribs are radially and synchronously extruded to be engaged with the corresponding FRP longitudinal reinforcement surface, and a tapered first protruding part is formed at both ends of the additional aluminum ribs, an open cavity is formed in the first protruding part, and one or more second protruding parts are formed in the middle of the additional aluminum ribs, and a closed cavity is formed in the second protruding part. The open cavity is used to prevent stress concentration from damaging the FRP longitudinal reinforcement, and after the concrete is poured, the open cavity is filled with concrete to increase the friction and engagement force of the FRP longitudinal reinforcement surface after the additional aluminum ribs are anchored, and to suppress the interface slip between the whole FRP longitudinal reinforcement and the concrete.

[0019] The application also provides a non-magnetic concrete for the concrete frame structure as described above, which comprises, by weight parts: non-magnetic cement 360-500 parts, non-magnetic fine aggregate 700-800 parts, non-magnetic coarse aggregate 950-1200 parts, water 150-180 parts, water reducing agent 0.2-0.4 parts, functional additive 0-0.2 parts; the residual magnetism of each component is less than 1 nT.

[0020] Further, the non-magnetic cement is white portland cement with a ferromagnetic substance content of less than 0.1%, and a residual magnetism of less than 1 nT.

[0021] Further, the non-magnetic fine aggregate is pure quartz stone sand or limestone with ferromagnetic substance content less than 0.1%, fineness modulus of 2.3-3, and residual magnetism intensity less than 1nT.

[0022] Further, the non-magnetic coarse aggregate is pure quartz stone or limestone with ferromagnetic substance content less than 0.1% and residual magnetism intensity less than 1nT.

[0023] Further, the functional additive is a temperature rise inhibitor or MgO expansion agent.

[0024] The non-magnetic concrete adopted in the application has a residual magnetism intensity less than 1nT (ordinary concrete reaches hundreds of nT), ensuring the stability of the magnetic field environment and effectively avoiding the interference of the magnetic field on high-precision equipment and instruments. Meanwhile, the mechanical properties and construction work performance of the non-magnetic concrete are basically the same as those of conventional concrete.

[0025] The FRP bar for the non-magnetic concrete reinforcing structure in the application can provide more excellent tensile strength and corrosion resistance than steel bars, and has no magnetism (less than 0.2nT), which can meet the strict requirements of extremely weak magnetic infrastructure on the magnetic field.

[0026] The application introduces the non-magnetic additional aluminum rib structure on the FRP bar, which can effectively shorten the anchoring length of the FRP bar in the concrete, increase the anchoring performance with the non-magnetic concrete, prevent the slip or even pull-out of the bar under long-term load or earthquake action, ensure the magnetic stability and structural safety of the FRP bar non-magnetic concrete frame structure during the service life, and provide strong support for the development and application of frontier scientific research technology. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0028] Figure 1 is a schematic diagram of a concrete frame structure in the application;

[0029] Figure 2 is a schematic diagram of the stress mechanism of the additional aluminum rib-FRP interface in the application;

[0030] Figure 3 is a CT scan result diagram of the additional aluminum rib-FRP interface in the application;

[0031] Figure 4 is a concrete compressive strength test result diagram of the application example;

[0032] Figure 5 is a concrete XRD result chart of the application example in the present application;

[0033] Figure 6 is a concrete thermogravimetric result chart of the application example in the present application;

[0034] In the figure: 1, FRP beam longitudinal reinforcement; 2, additional aluminum rib; 3, non-magnetic concrete; 4, FRP column longitudinal reinforcement; 5, non-magnetic concrete beam; 6, non-magnetic concrete column; 9, FRP stirrup; 10, first protruding part; 11, open cavity; 12, second protruding part; 13, closed cavity. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0036] Embodiment 1:

[0037] This embodiment is an additional aluminum rib FRP bar non-magnetic concrete frame structure facing a non-magnetic environment, which comprises FRP beam longitudinal reinforcement 1, FRP column longitudinal reinforcement 4, non-magnetic concrete 3 and a plurality of additional aluminum ribs 2. The additional aluminum ribs 2 are anchored at both ends of the FRP beam longitudinal reinforcement 1 and the top end of the FRP column longitudinal reinforcement 4, and the FRP beam longitudinal reinforcement 1 and the FRP column longitudinal reinforcement 4 are arranged in the non-magnetic concrete 3 without bending, wherein the FRP beam longitudinal reinforcement 1 and the non-magnetic concrete 3 wrapped thereon form a non-magnetic concrete beam 5, and the FRP column longitudinal reinforcement 4 and the non-magnetic concrete 3 wrapped thereon form a non-magnetic concrete column 6, thereby forming a concrete frame structure as a whole. The non-magnetic concrete 3 needs to select non-magnetic concrete with a residual magnetism less than 1 nT, so as to effectively avoid the interference of magnetic substances on high-precision equipment and instruments.

[0038] Anchoring length L of FRP bar in concrete d , that is, the minimum embedded length required to fully develop the ultimate tensile strength of the FRP bar. For the test piece without setting the aluminum rib, the FRP bar in the concrete can be obtained according to the force balance relationship:

[0039]

[0040] Where τ u is the ultimate interfacial bond strength; f tu , d, A are the ultimate tensile strength, diameter and cross-sectional area of the FRP bar respectively; L d0 is the anchoring length of the FRP bar without setting the additional aluminum rib.

[0041] The research shows that there is a strong correlation between the ultimate bond strength and the square root of the compressive strength of concrete:

[0042]

[0043] where K is a parameter obtained from experiments; f c is the axial compressive strength of cylindrical concrete, which is about 0.8 times the cubic compressive strength.

[0044] Then the combined two formulas are obtained:

[0045]

[0046] According to the test data in Table 1 in the embodiment, E is 11.78, and the linear regression can obtain the final tensile stress f t of the FRP and the bond length L:

[0047]

[0048] B = 0.085

[0049] Finally, the anchorage length of the FRP without the additional aluminum rib 2 is:

[0050]

[0051] For the specimen with the aluminum rib, the final stress f ta of the FRP in the concrete is improved relative to the FRP without the aluminum rib, and the following can be obtained:

[0052]

[0053] where i is an equivalent interface enhancement coefficient related to the additional aluminum rib 2, which is related to the ratio of the interface strength of the aluminum alloy and the FRP to the interface strength of the FRP and the concrete, and the specific value is determined according to the regression of the experimental data.

[0054] The anchorage length of the FRP with the additional aluminum rib 2 is the same as the derivation of the FRP without the additional aluminum rib 2 above:

[0055]

[0056] In the embodiment, the regression analysis after the pull-out test obtains that i of the concrete specimen with only one additional aluminum rib 2 structure anchoring can be 0.2. It can be found that the anchorage length L d0 of the FRP with the additional aluminum rib 2 structure anchoring is d about 0.83L d0, reduced by about 16.7% (about 4d). This result shows that, in the case of no bending anchor, the application of additional aluminum rib 2 anchoring system can effectively reduce the anchorage length of FRP bars, thereby improving their safety.

[0057] Preferably, a plurality of additional aluminum ribs 2 are anchored at both ends of the FRP beam longitudinal reinforcement 1, and the net spacing between adjacent additional aluminum ribs 2 at the same end is 50-100 mm. Providing multiple additional aluminum ribs 2 can further enhance the anchoring strength.

[0058] Preferably, a plurality of additional aluminum ribs 2 are anchored at the top end of the FRP column longitudinal reinforcement 4, and the net spacing between adjacent additional aluminum ribs 2 at the top end is 50-100 mm. Providing multiple additional aluminum ribs 2 can further enhance the anchoring strength.

[0059] Furthermore, it also includes a plurality of FRP stirrups 9, which are parallel to the FRP beam longitudinal bars 1 and the FRP column longitudinal bars 4. The FRP stirrups 9 connect the FRP beam longitudinal bars 1 and the FRP column longitudinal bars 4 to increase the overall strength of the concrete structure.

[0060] Preferably, the FRP stirrups are formed by stacking and winding FRP fibers impregnated with resin, and forming FRP stirrups after curing.

[0061] like Figure 1 The concrete frame structure shown includes a non-magnetic concrete beam 5 and a non-magnetic concrete column 6. FRP beam longitudinal reinforcement 1 and FRP stirrups 9 are arranged in the non-magnetic concrete beam 5, and FRP column longitudinal reinforcement 4 and FRP stirrups 9 are arranged in the non-magnetic concrete column 6. The FRP beam longitudinal reinforcement 1 at the end of the non-magnetic concrete beam 5 extends into the non-magnetic concrete column 6. Additional aluminum ribs 2 are provided on the FRP beam longitudinal reinforcement 1 at the end of the non-magnetic concrete beam 5 to improve the anchoring performance. Additional aluminum ribs 2 are provided on the FRP column longitudinal reinforcement 4 at the top of the non-magnetic concrete column 6 to improve the anchoring performance. Both the FRP longitudinal reinforcement and stirrups are FRP reinforcements, and the additional aluminum ribs 2 are 6061-T6 aluminum tubes, which are anchored to the FRP reinforcements by extrusion. The interface stress mechanism between the additional aluminum ribs 2 and the FRP longitudinal reinforcements is as shown in the figure. Figure 2 As shown, this embodiment takes the FRP beam longitudinal reinforcement 1 as an example. When the additional aluminum rib 2 is anchored, the additional aluminum rib 2 is synchronously extruded radially so that the additional aluminum rib 2 bites into the surface of the FRP beam longitudinal reinforcement 1, and a conical first protrusion 10 is formed at both ends of the additional aluminum rib 2, and an open cavity 11 is formed in the first protrusion 10. At the same time, one or more second protrusions 12 are formed in the middle of the additional aluminum rib 2, and a closed cavity 13 is formed in the second protrusion 12. The open cavity 11 is used to prevent stress concentration from damaging the FRP longitudinal reinforcement. After pouring concrete, concrete is poured into the open cavity 11 to increase the friction and bite force on the surface of the FRP longitudinal reinforcement at that location after the additional aluminum rib is anchored. Figure 3As shown, according to the CT scanning result, the final aluminum rib-FRP bar interface failure is accompanied by the peeling of the surface shallow layer resin and fiber of the FRP bar, and the main body of the FRP bar is almost undamaged. At the same time, the structure of the protrusion 10 can provide stable additional constraint force, and finally achieve the high strength characteristics of the interface. Stirring non-magnetic concrete using a non-magnetic stirring device, or stirring non-magnetic concrete after coating a magnetic stirring device, can effectively avoid the introduction of ferromagnetic substances.

[0062] Application Example 1:

[0063] The non-magnetic concrete beam 5 and the non-magnetic concrete column 6 are constructed according to the weight parts of the concrete materials, and the concrete materials are weighed according to the weight parts, 14.17 parts of white cement, 26.5 parts of pure white quartz sand (of which the white quartz sand is divided into five mesh sizes, and the ratio is 7-14 mesh: 14-30 mesh: 30-50 mesh: 50-100 mesh: 100-500 mesh = 20:40:20:10:10), 39.17 parts of pure white quartz stone (of which it is divided into three kinds of particle size stones, 5-8mm:8-12mm:12-16mm = 40:40:20), 5.81 parts of water, 0.028 parts of water reducing agent, and 0.035 parts of temperature rise inhibitor. After weighing, the concrete is mixed on the plastic board using a plastic shovel to obtain the non-magnetic concrete beam 5 and the non-magnetic concrete column 6. The FRP longitudinal reinforcement is a threaded CFRP bar with a diameter of 10mm. The FRP stirrup 9 is a threaded CFRP bar with a diameter of 7mm. The additional aluminum rib 2 extending into the node area is a 6061-T6 aluminum pipe with a thickness of 5mm, an outer diameter of 22mm, and a length of 20mm, with a spacing of 50mm.

[0064] Application Example 2:

[0065] The non-magnetic concrete beam 5 and the non-magnetic concrete column 6 are constructed according to the weight parts of the concrete materials, and the concrete materials are weighed according to the weight parts, 14.17 parts of white cement, 23.64 parts of pure white quartz sand (of which the white quartz sand is divided into five mesh sizes, and the ratio is 7-14 mesh: 14-30 mesh: 30-50 mesh: 50-100 mesh: 100-500 mesh = 25:35:20:10:10), 33.94 parts of pure white quartz stone (of which it is divided into three kinds of particle size stones, 5-8mm:8-12mm:12-16mm = 40:40:20), 5.54 parts of water, 0.035 parts of water reducing agent. After weighing, the concrete is mixed on the plastic board using a plastic shovel to obtain the non-magnetic concrete beam 5 and the non-magnetic concrete column 6. The FRP longitudinal reinforcement is a threaded CFRP bar with a diameter of 10mm. The FRP stirrup 9 is a threaded CFRP bar with a diameter of 7mm. The additional aluminum rib 2 extending into the node area is a 6061-T6 aluminum pipe with a thickness of 5mm, an outer diameter of 22mm, and a length of 20mm, with a spacing of 100mm.

[0066] Application Example 3:

[0067] Concrete materials for the non-magnetic concrete beam 5 and column 6 were weighed according to weight: 14.17 parts white cement, 20.23 parts pure white quartz sand (white quartz sand is available in five mesh sizes, with a ratio of 7-14 mesh, 14-30 mesh, 30-50 mesh, 50-100 mesh, and 100-500 mesh = 25:35:20:10:10), 29.08 parts pure white quartz stone (available in three particle sizes: 5-8 mm, 8-12 mm, and 12-16 mm = 40:40:20), 4.53 parts water, and 0.057 parts water reducer. After weighing, the concrete was mixed on a plastic board using a plastic spatula to produce the non-magnetic concrete beam 5 and column 6. The FRP longitudinal bars were threaded CFRP bars with a diameter of 10 mm. The FRP stirrups 9 were threaded CFRP bars with a diameter of 7 mm. The additional aluminum ribs 2 extending into the node area are 6061-T6 aluminum tubes with a thickness of 5 mm, an outer diameter of 22 mm, and a length of 20 mm, with a spacing of 100 mm.

[0068] Application Example 4:

[0069] The non-magnetic concrete beam 5 and non-magnetic concrete column 6 are constructed by weighing the concrete materials according to weight: 14.17 parts of ordinary Portland cement, 16.55 parts of river sand, 35.22 parts of basalt stone, and 5.80 parts of water. After weighing, a plastic shovel is used to mix the concrete on a plastic board to prepare the non-magnetic concrete beam 5 and non-magnetic concrete column 6. The FRP longitudinal reinforcement is a threaded CFRP reinforcement with a diameter of 10mm. The FRP stirrups 9 are threaded CFRP reinforcements with a diameter of 7mm. The additional aluminum ribs 2 extending into the node area are 6061-T6 aluminum tubes with a thickness of 5mm, an outer diameter of 22mm, and a length of 20mm, with a spacing of 100mm.

[0070] The concrete obtained from each application example was subjected to mechanical and micro-performance tests. The results are as follows: Figures 4-5 See Figure 4 The 28-day average compressive strength of Application Example 1 reached over 40 MPa, Application Example 2 over 48 MPa, and Application Example 3 over 58 MPa, meeting the strength requirements of the specification. The residual magnetism of Application Examples 1-3 was all less than 1 nT, making them suitable for non-magnetic concrete frame construction. Application Example 4, using ordinary Portland cement concrete, met the strength requirements, but its residual magnetism did not meet the requirements for extremely weak magnetic infrastructure construction.

[0071] See also Figure 5From the XRD results, it can be seen that the crystalline phase in the non-magnetic concrete product contains a large amount of quartz, which is due to the use of mainly quartzite aggregate. Compared with Application Examples 1-3, Application Example 4 contains a clear AFt ettringite peak, which is generated by the hydration of the cement alumina phase, and the white cement contains less aluminum phase (2.33%), so the AFt peak is not obvious. In addition, the hydration product types of Application Examples 1-4 are basically the same, and the white cement concrete of different examples has no effect on the product type.

[0072] Referring to Figure 6 The thermogravimetric results show that as the temperature increases from 30°C to 1000°C, there is a large mass loss between 30°C-200°C, which is mainly due to the reduction of free water as the temperature rises. The mass loss between 380°C-450°C is mainly due to the loss of water from calcium hydroxide. The calcium hydroxide content of Application Examples 1-3 is slightly higher than that of the ordinary silica concrete group, because the white cement mineral phase is mainly composed of C3S and C2S minerals, and more calcium hydroxide is generated by hydration. The mass loss between 600°C-800°C is mainly due to the decomposition of calcium carbonate.

[0073] The above results show the difference between white cement non-magnetic concrete and ordinary silica concrete. Due to the lack of C4AF in the system, which continues to hydrate in the later stage, the density of white cement non-magnetic concrete is slightly lower than that of ordinary silica concrete, but the strength is not affected, and the strength of non-magnetic concrete still meets the requirements.

[0074] A direct pull test was conducted on the FRP bar concrete test block with additional aluminum ribs in the present application to determine the improvement of the anchoring effect of the additional aluminum ribs 2. The test was conducted on a universal testing machine at a loading rate of 1.2 mm / min. The test results are shown in Table 1:

[0075]

[0076]

[0077] In the test specimen number, the number after the letter L represents the bonding length, and the number after the letter R represents the number of aluminum ribs used. Each group has three test specimens, named 1, 2, and 3. The additional aluminum ribs 2 have a thickness of 5 mm, an outer diameter of 22 mm, and a length of 20 mm. After being extruded and anchored behind the FRP bar, the length becomes 25 mm.

[0078] Example 2:

[0079] The present embodiment is a non-magnetic concrete used in the concrete frame structure in the above embodiment, which comprises, by weight: non-magnetic cement 360-500 parts, non-magnetic fine aggregate 700-800 parts, non-magnetic coarse aggregate 950-1200 parts, water 150-180 parts, water reducing agent 0.2-0.4 parts, and functional additive 0-0.2 parts. The non-magnetic cement in the present embodiment is white Portland cement with ferromagnetic substance content less than 0.1%, and residual magnetization less than 1 nT. The non-magnetic fine aggregate is pure quartz sand or limestone with ferromagnetic substance content less than 0.1%, fineness modulus 2.3-3, and residual magnetization less than 1 nT. The non-magnetic coarse aggregate is pure quartz or limestone with ferromagnetic substance content less than 0.1%, and residual magnetization less than 1 nT. The functional additive is temperature rise inhibitor or MgO expansion agent. In other embodiments, suitable non-magnetic components can also be selected.

[0080] Obviously, various modifications and changes can be made to the present application by those skilled in the art without departing from the spirit and scope of the present application. Accordingly, it is intended that the present application embrace all such modifications and changes as fall within the scope of the claims and their equivalents.

Claims

1. A non-magnetic concrete frame structure with additional aluminum ribs and FRP bars, characterized in that: It includes FRP beam longitudinal reinforcement, FRP column longitudinal reinforcement, non-magnetic concrete and several additional aluminum ribs; the additional aluminum ribs are anchored at both ends of the FRP beam longitudinal reinforcement and the top of the FRP column longitudinal reinforcement, and the FRP beam longitudinal reinforcement and FRP column longitudinal reinforcement are set in the non-magnetic concrete without bending, forming a concrete frame structure; A plurality of additional aluminum ribs are anchored at both ends of the FRP beam longitudinal reinforcement and / or at the top end of the FRP column longitudinal reinforcement. When the additional aluminum ribs are anchored, the additional aluminum ribs are radially and synchronously extruded so that the additional aluminum ribs engage with the corresponding FRP longitudinal reinforcement surfaces, and conical first protrusions are formed at both ends of the additional aluminum ribs, with open cavities formed in the first protrusions. At the same time, one or more second protrusions are formed in the middle of the additional aluminum ribs, with closed cavities formed in the second protrusions. Select the number n of additional aluminum ribs according to the anchorage length, and set the anchorage length of the FRP beam longitudinal reinforcement and / or FRP column longitudinal reinforcement of the additional aluminum ribs to: Where, L d is the anchorage length, B is the coefficient, f tu is the ultimate tensile strength of FRP bar, d is the diameter of FRP bar, f c is the axial compressive strength of cylindrical concrete, i is the equivalent interface reinforcement coefficient linearly related to n; Where, τ u is the ultimate bond strength of the interface; Where A is the cross-sectional area of ​​the FRP reinforcement, L d0 It is the anchorage length of FRP bars without additional aluminum ribs.

2. The non-magnetic concrete frame structure with additional aluminum ribs and FRP bars according to claim 1 is characterized in that: The residual magnetic strength of the FRP beam longitudinal reinforcement and FRP column longitudinal reinforcement is less than 0.2nT, and the residual magnetic strength of the additional aluminum rib is less than 0.5nT.

3. The non-magnetic concrete frame structure with additional aluminum ribs and FRP bars according to claim 1, characterized in that: It also includes a number of FRP stirrups, which are parallel to the FRP beam longitudinal bars and the FRP column longitudinal bars. The FRP stirrups are tied with the FRP beam longitudinal bars and the corresponding FRP column longitudinal bars to form an FRP reinforcement skeleton of the frame structure. The residual magnetic strength of the FRP stirrups is lower than 0.2nT.

4. The non-magnetic concrete frame structure with additional aluminum ribs and FRP bars according to claim 3 is characterized in that: The FRP stirrups are formed by stacking and winding FRP fibers impregnated with resin and forming the FRP stirrups after solidification.

5. A non-magnetic concrete used for the concrete frame structure according to any one of claims 1 to 4, characterized in that: The composition includes, by weight, 360-500 parts of non-magnetic cement, 700-800 parts of non-magnetic fine aggregate, 950-1200 parts of non-magnetic coarse aggregate, 150-180 parts of water, 0.2-0.4 parts of water reducer, and 0-0.2 parts of functional additives; the residual magnetic intensity of each component is lower than 1nT.

6. The non-magnetic concrete according to claim 5, characterized in that: The non-magnetic cement is white silicate cement with a ferromagnetic content of less than 0.1% and a residual magnetic intensity of less than 1 nT.

7. The non-magnetic concrete according to claim 5, characterized in that: The non-magnetic fine aggregate is pure quartz sand or limestone with a ferromagnetic content of less than 0.1%, a fineness modulus of 2.3 to 3, and a residual magnetic intensity of less than 1nT; the non-magnetic coarse aggregate is pure quartz stone or limestone with a ferromagnetic content of less than 0.1%, and a residual magnetic intensity of less than 1nT.

8. The non-magnetic concrete according to claim 5, characterized in that: The functional additive is a temperature rise inhibitor or a MgO expansion agent.

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