Non-magnetic concrete frame structure with additional aluminum ribs and FRP bars and non-magnetic concrete

Abstract

The invention relates to a non-magnetic concrete frame structure with additional aluminum ribs and FRP ribs and non-magnetic concrete. The concrete frame structure comprises FRP beam longitudinal ribs, the additional aluminum ribs, FRP column longitudinal ribs and the non-magnetic concrete. The additional aluminum ribs are anchored at the two ends of the FRP beam longitudinal bars and the top ends of the FRP column longitudinal bars respectively, the anchoring length needed by the FRP bars is effectively reduced, and the FRP beam longitudinal bars and the FRP column longitudinal bars are arranged in the non-magnetic concrete in a non-bending mode. The non-magnetic concrete is prepared from the following components in parts by weight: 360 to 500 parts of non-magnetic cement, 700 to 800 parts of non-magnetic fine aggregate, 950 to 1200 parts of non-magnetic coarse aggregate, 150 to 180 parts of water, 0.2 to 0.4 part of water reducing agent and 0 to 0.2 part of functional additive, and the residual magnetism intensity of each component is lower than 1nT. The FRP bars with the remanence intensity smaller than 0.2 nT and the non-magnetic concrete with the remanence intensity smaller than 1 nT are adopted, and interference of magnetic substances (remanence reaches thousands or even tens of thousands of nT) in conventional steel bars and concrete on high-precision equipment and instruments is effectively avoided. And the service magnetic stability of the structure in the life cycle is effectively guaranteed, and powerful support is provided for development and application of the preceding 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 a 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, 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 capabilities of non-magnetic seismic stations has become increasingly urgent.

[0003] The construction of extremely weak magnetic infrastructure faces multiple challenges in materials and structural technologies. Existing technologies and materials are difficult to fully meet the special needs of non-magnetic environments (<1nT). The remanence of conventional concrete reaches hundreds of nT. Currently, there is no low-magnetic concrete that can simultaneously meet the remanence index requirements as well as mechanical properties and construction performance. In terms of reinforcement materials, traditional carbon steel bars or alloy steel bars will cause serious magnetic field interference. The mechanical properties of copper alloy bars cannot meet the requirements for use as force-bearing reinforcement materials in large building spaces.

[0004] Fiber reinforced plastic (FRP) is a new type of lightweight and high-strength material with excellent corrosion resistance and mechanical properties, and the residual magnetic intensity is 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 on the use of fiber reinforced plastics as load-bearing reinforcement in ordinary concrete structures have been carried out, 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 anchoring length. The tensile strength of FRP tendons is significantly reduced after bending and anchoring, which makes it difficult to effectively anchor FRP tendons 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 above-mentioned prior art, the present invention provides a non-magnetic concrete frame structure with additional aluminum ribs and FRP bars, including FRP beam longitudinal bars, FRP column longitudinal bars, non-magnetic concrete and a number of additional aluminum ribs; the additional aluminum ribs are anchored at both ends of the FRP beam longitudinal bars and the top of the FRP column longitudinal bars, respectively, and the FRP beam longitudinal bars and the FRP column longitudinal bars are arranged in the non-magnetic concrete without bending, wherein the FRP beam longitudinal bars and the non-magnetic concrete coated thereon form a non-magnetic concrete beam, and the FRP column longitudinal bars and the non-magnetic concrete coated thereon form a non-magnetic concrete column, forming a concrete frame structure as a whole. The FRP beam longitudinal bars and the FRP column longitudinal bars are not limited to a complete FRP bar, but can also be a straight bar formed by overlapping and connecting a number of FRP bars. The additional aluminum ribs can also be used for other FRP bar ends that require additional anchoring.

[0006] FRP is used as a force-bearing reinforcement in non-magnetic concrete, which can make the concrete frame structure non-magnetic as a whole and at a low cost. Anchoring additional aluminum ribs at both ends of the FRP beam longitudinal reinforcement and the top of the FRP column longitudinal reinforcement can increase the anchoring performance and seismic resistance of the area.

[0007] The setting of a single additional aluminum rib can greatly reduce the anchorage length of FRP bars in concrete, effectively increasing the anchorage performance with non-magnetic concrete, and preventing the bars and concrete from sliding or even pulling out under long-term or seismic loads. At the same time, since the additional aluminum ribs increase the anchorage performance and reduce the anchorage length, the FRP beam longitudinal bars and FRP column longitudinal bars do not need to be bent and anchored, avoiding the excessive anchorage length of the FRP longitudinal bars and the weakening of strength caused by the bending and anchoring. The anchorage performance of FRP bars in concrete can be increased within a limited length without bending and anchoring, solving the key problem of using FRP bars to form concrete frame structures.

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

[0009] Furthermore, it also includes a plurality of FRP stirrups, wherein a plurality of FRP beam longitudinal bars and FRP column longitudinal bars are arranged in parallel, and the FRP stirrups are tied with each FRP beam longitudinal bar and each corresponding FRP column longitudinal bar to form a FRP reinforcement skeleton of the frame structure, and the residual magnetic strength of the FRP stirrups is lower than 0.2nT.

[0010] Furthermore, the FRP stirrups are formed by stacking and winding FRP fibers impregnated with resin, and then solidified to form FRP stirrups. Pultruded FRP stirrups are very likely to be damaged in the overlap section or corner area, thereby weakening the restraint effect on concrete. The wound FRP stirrups are directly made into stirrups of the required shape and size, and a single FRP fiber is not broken throughout the entire length, ensuring that there are no wrinkles or kinks at the bends, which can effectively ensure the restraint effect of the stirrups.

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

[0012]

[0013] 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 considering the ratio of the interface strength between aluminum alloy and FRP to the interface strength between FRP bars and concrete, which is linearly related to n and the specific value is determined by regression based on experimental data;

[0014]

[0015] In the formula, τ u is the interface ultimate bonding strength;

[0016]

[0017] Where A is the cross-sectional area of ​​the FRP reinforcement, L d0 It is the anchorage length of FRP reinforcement without additional aluminum ribs.

[0018] Furthermore, when the additional aluminum rib is anchored, the additional aluminum rib is synchronously extruded radially so that the additional aluminum rib bites into the corresponding FRP longitudinal reinforcement surface, and a conical first protrusion is formed at both ends of the additional aluminum rib, and an open cavity is formed in the first protrusion. At the same time, one or more second protrusions are formed in the middle of the additional aluminum rib, and a closed cavity is formed in the second protrusion. The open cavity is used to prevent stress concentration from damaging the FRP longitudinal reinforcement. After pouring concrete, concrete is poured into the open cavity 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, thereby suppressing the interface slip between the FRP longitudinal reinforcement as a whole and the concrete.

[0019] The present invention also provides a non-magnetic concrete for the concrete frame structure as described above, which comprises, 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 less than 1nT.

[0020] Furthermore, 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 1nT.

[0021] Furthermore, 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 1 nT.

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

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

[0024] The non-magnetic concrete used in the present invention has a residual magnetic strength of less than 1nT (common concrete reaches hundreds of nT), which ensures the stability of the magnetic field environment and effectively avoids the interference of the magnetic field on high-precision equipment and instruments. At the same time, its mechanical properties and construction performance are basically the same as those of conventional concrete.

[0025] The FRP bars used in the non-magnetic concrete reinforcement structure of the present invention can provide better tensile strength and corrosion resistance than steel bars, and their non-magnetic properties (less than 0.2nT) can better meet the strict requirements of extremely weak magnetic infrastructure on the magnetic field.

[0026] The present invention introduces a non-magnetic additional aluminum rib structure on the FRP bar, which can effectively shorten the anchorage length of the FRP bar in the concrete, increase the anchorage performance with the non-magnetic concrete, and prevent the slippage or even pullout of the bar under long-term load or earthquake action, thereby ensuring the magnetic stability and structural safety of the FRP bar non-magnetic concrete frame structure during its service life, and providing strong support for the development and application of cutting-edge scientific research technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0029] Figure 2 Schematic diagram of the stress mechanism of the additional aluminum rib-FRP interface in the present invention;

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

[0031] Figure 4 is a graph showing the concrete compressive strength test results of an application example of the present invention;

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

[0033] Figure 6 It is the thermogravimetric result diagram of concrete of the application example in the present invention;

[0034] In the figure: 1. FRP beam longitudinal reinforcement; 2. Additional aluminum ribs; 3. Non-magnetic concrete; 4. FRP column longitudinal reinforcement; 5. Non-magnetic concrete beam; 6. Non-magnetic concrete column; 9. FRP stirrups; 10. First protrusion; 11. Open cavity; 12. Second protrusion; 13. Closed cavity. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Embodiment 1:

[0037] This embodiment is an additional aluminum rib FRP bar non-magnetic concrete frame structure for non-magnetic environment, including FRP beam longitudinal bars 1, FRP column longitudinal bars 4, non-magnetic concrete 3 and a number of additional aluminum ribs 2. The additional aluminum ribs 2 are anchored at both ends of the FRP beam longitudinal bars 1 and the top of the FRP column longitudinal bars 4. The FRP beam longitudinal bars 1 and the FRP column longitudinal bars 4 are arranged in the non-magnetic concrete 3 without bending, wherein the FRP beam longitudinal bars 1 and the non-magnetic concrete 3 coated thereon form a non-magnetic concrete beam 5, and the FRP column longitudinal bars 4 and the non-magnetic concrete 3 coated thereon form a non-magnetic concrete column 6, forming a concrete frame structure as a whole. The non-magnetic concrete 3 needs to be selected with a residual magnetic strength of less than 1nT to effectively avoid the interference of magnetic substances on high-precision equipment and instruments.

[0038] Anchorage length L of FRP bars in concrete d , which is the minimum embedding length required to fully exert the ultimate tensile strength of the FRP bar. For the specimen without aluminum ribs, the FRP bar in the concrete can be obtained based on the force balance relationship:

[0039]

[0040] where τ u is the interface ultimate bonding strength; f tu , d, A are the ultimate tensile strength, diameter and cross-sectional area of ​​FRP bars respectively; L d0 It is the anchorage length of FRP reinforcement without additional aluminum ribs.

[0041] Studies have shown a strong correlation between the ultimate bond strength and the square root of the concrete compressive strength:

[0042]

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

[0044] Then combining the two formulas we can get:

[0045]

[0046] According to the test data in Table 1 of this embodiment, E is 11.78, and the final tensile stress f of FRP can be obtained after linear regression. t Relationship with bonding length L:

[0047]

[0048] B=0.085

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

[0050]

[0051] For the specimen with aluminum ribs, the final stress of FRP bars in concrete is f ta Compared with the FRP without aluminum ribs, the stress is increased, and it can be obtained:

[0052]

[0053] Where i is the equivalent interface reinforcement coefficient related to the additional aluminum rib 2, which is related to the ratio of the interface strength between the aluminum alloy and FRP to the interface strength between the FRP bar and concrete. The specific value is determined by regression based on experimental data.

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

[0055]

[0056] In this embodiment, after the pull-out test, regression analysis shows that the i of the concrete specimen with only one additional aluminum rib 2 for structural anchoring can be taken as 0.2. It is obvious that the FRP tendon anchorage length L is d0 In comparison, the anchorage length L of the concrete specimen with an additional aluminum rib 2 structure anchor 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 tendons, 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. Arranging a plurality of 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. Arranging a plurality of additional aluminum ribs 2 can further enhance the anchoring strength.

[0059] Furthermore, it also includes a plurality of FRP stirrups 9, and a plurality of FRP beam longitudinal bars 1 and FRP column longitudinal bars 4 are arranged in parallel. 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 then curing to form FRP stirrups.

[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 arranged 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 arranged 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 extruding the aluminum ribs. 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 radially and synchronously extruded 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 in the figure, the CT scanning results show that the aluminum rib-FRP bar interface is finally destroyed with the peeling of the shallow resin and fiber on the surface of the FRP bar, and the FRP bar body is almost undamaged. At the same time, the structure of the protrusion 10 can provide a stable additional restraining force, and finally achieve the high-strength characteristics of the interface. Using a non-magnetic stirring device to stir non-magnetic concrete, 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 by weighing the concrete materials according to the weight parts, 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 (wherein 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 (wherein it is divided into three kinds of stone with different particle sizes, 5-8mm: 8-12mm: 12-16mm = 40:40:20), 5.81 parts of water, 0.028 parts of water reducer, and 0.035 parts of temperature rise inhibitor. After weighing, use a plastic shovel to mix the concrete on the plastic board to prepare the non-magnetic concrete beam 5 and the 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 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 50 mm.

[0064] Application Example 2:

[0065] The non-magnetic concrete beam 5 and the non-magnetic concrete column 6 are constructed by weighing the concrete materials according to the weight parts, 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 (wherein 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 (wherein it is divided into three kinds of stone with different particle sizes, 5-8mm: 8-12mm: 12-16mm = 40:40:20), 5.54 parts of water, and 0.035 parts of water reducer. After weighing, a plastic shovel is used to mix the concrete on the plastic board to prepare the non-magnetic concrete beam 5 and the non-magnetic concrete column 6. The FRP longitudinal reinforcement is a threaded CFRP reinforcement with a diameter of 10mm. The FRP stirrup 9 is a threaded CFRP reinforcement with a diameter of 7mm. 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, and the spacing is 100 mm.

[0066] Application Example 3:

[0067] The non-magnetic concrete beam 5 and the non-magnetic concrete column 6 are constructed by weighing the concrete materials according to the weight parts, and the concrete materials are weighed according to the weight parts, 14.17 parts of white cement, 20.23 parts of pure white quartz sand (wherein 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), 29.08 parts of pure white quartz stone (wherein it is divided into three kinds of stone with different particle sizes, 5-8mm: 8-12mm: 12-16mm = 40:40:20), 4.53 parts of water, and 0.057 parts of water reducer. After weighing, a plastic shovel is used to mix the concrete on the plastic board to prepare the non-magnetic concrete beam 5 and the non-magnetic concrete column 6. The FRP longitudinal reinforcement is a threaded CFRP reinforcement with a diameter of 10mm. The FRP stirrup 9 is a threaded CFRP reinforcement with a diameter of 7mm. 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, and the spacing is 100 mm.

[0068] Application example 4:

[0069] The non-magnetic concrete beam 5 and the non-magnetic concrete column 6 are constructed by weighing the concrete materials according to weight, and the concrete materials are weighed 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 the plastic board to prepare the non-magnetic concrete beam 5 and the non-magnetic concrete column 6. The FRP longitudinal reinforcement is a threaded CFRP reinforcement with a diameter of 10mm. The FRP stirrup 9 is a threaded CFRP reinforcement with a diameter of 7mm. The additional aluminum rib 2 extending into the node area is a 6061-T6 aluminum tube 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 property tests and microscopic property tests. The results are as follows: Figure 4-5 See Figure 4 The 28d average compressive strength of Application Example 1 can reach more than 40MPa, Application Example 2 can reach more than 48MPa, and Application Example 3 can reach more than 58MPa, meeting the strength requirements of the specification. The residual magnetism of Application Examples 1-3 is less than 1nT, which can be used for the construction of non-magnetic concrete frame structures. Application Example 4 uses ordinary Portland cement concrete. Although the strength meets the requirements, the residual magnetism does not meet the requirements for extremely weak magnetic infrastructure construction.

[0071] See also Figure 5Through the XRD results, it can be seen that the non-magnetic concrete product contains a large amount of quartz in the crystalline phase, which is due to the use of quartz aggregate. Compared with application examples 1-3, application example 4 contains obvious AFt calcium aluminate peaks, which are generated by the hydration of aluminum phase clinker in cement, and the aluminum phase content in white cement is relatively low (2.33%), so the AFt peak is not obvious. In addition, the types of hydration products in application examples 1-4 are basically the same, and white cement concrete in different examples has no effect on the types of products.

[0072] See also Figure 6 The thermogravimetric results show that as the temperature increases from 30℃ to 1000℃, there is a large mass loss between 30℃-200℃, which is mainly due to the reduction of free water as the temperature rises. The mass loss between 380℃-450℃ is mainly due to the dehydration of calcium hydroxide. The calcium hydroxide content of application examples 1-3 is slightly higher than that of ordinary silicon concrete. This is because the mineral phase of white cement is mainly composed of C3S and C2S minerals, and hydration easily generates more calcium hydroxide. The mass loss between 600℃-800℃ is mainly due to the decomposition of calcium carbonate.

[0073] The above results show the difference between white cement non-magnetic concrete and ordinary silicon concrete. Due to the lack of C4AF for later continuous hydration in the system, the density of white cement non-magnetic concrete is slightly lower than that of ordinary silicon concrete, but it has little effect on the strength. The strength of non-magnetic concrete can still meet the requirements.

[0074] A direct pull-out test was conducted on the FRP reinforced concrete test block with additional aluminum ribs in the present invention to determine the improvement of the anchoring effect by 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 specimen number, the number after the letter L indicates the bonding length, and the number after the letter R indicates the number of aluminum ribs used. Each group has three specimens, named 1, 2, and 3. The specifications of the additional aluminum rib 2 are 5 mm thick, 22 mm in outer diameter, and 20 mm in length. After being extruded and anchored on the FRP bar, the length becomes 25 mm.

[0078] Embodiment 2:

[0079] This embodiment is non-magnetic concrete, which is used for the concrete frame structure in the above embodiment. Its 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 non-magnetic cement described in this embodiment is white silicate cement with a ferromagnetic content of less than 0.1% and a residual magnetic intensity of less than 1nT. The non-magnetic fine aggregate is pure quartz sand or limestone with a ferromagnetic content of less than 0.1%, and its fineness modulus is 2.3-3, and the residual magnetic intensity is less than 1nT. The non-magnetic coarse aggregate is pure quartz or limestone with a ferromagnetic content of less than 0.1%, and the residual magnetic intensity is less than 1nT. The functional additive is a temperature rise inhibitor or a MgO expansion agent. In other embodiments, suitable non-magnetic components can also be selected.

[0080] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

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 a number of 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 the FRP column longitudinal reinforcement are arranged in the non-magnetic concrete without bending to form a concrete frame structure.

2. The non-magnetic concrete frame structure with additional aluminum ribs and FRP bars according to claim 1 is characterized in that: A number of additional aluminum ribs are anchored at both ends of the FRP beam longitudinal reinforcement and / or the top of the FRP column longitudinal reinforcement. The residual magnetic strength of the FRP beam longitudinal reinforcement and the FRP column longitudinal reinforcement is less than 0.2nT, and the residual magnetic strength of the additional aluminum ribs is less than 0.5nT.

3. The non-magnetic concrete frame structure with additional aluminum ribs and FRP bars according to claim 1 is characterized in that: It also includes a plurality of FRP stirrups, wherein a plurality of FRP beam longitudinal bars and FRP column longitudinal bars are arranged in parallel, and the FRP stirrups are tied with each FRP beam longitudinal bar and each corresponding FRP column longitudinal bar to form a FRP reinforcement skeleton of the frame structure, and 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. The non-magnetic concrete frame structure with additional aluminum ribs and FRP bars according to claim 2 is characterized in that: 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; In the formula, τ u is the interface ultimate bonding strength; Where A is the cross-sectional area of ​​the FRP reinforcement, L d0 It is the anchorage length of FRP reinforcement without additional aluminum ribs.

6. The non-magnetic concrete frame structure with additional aluminum ribs and FRP bars according to claim 1 is characterized in that: When the additional aluminum rib is anchored, the additional aluminum rib is synchronously extruded radially so that the additional aluminum rib is engaged with the corresponding FRP longitudinal reinforcement surface, and a conical first protrusion is formed at both ends of the additional aluminum rib, an open cavity is formed in the first protrusion, and one or more second protrusions are formed in the middle of the additional aluminum rib, and a closed cavity is formed in the second protrusion.

7. A non-magnetic concrete used for the concrete frame structure according to any one of claims 1 to 6, 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 reducing agent, and 0-0.2 parts of functional additives; the residual magnetic strength of each component is lower than 1nT.

8. The non-magnetic concrete according to claim 7, 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.

9. The non-magnetic concrete according to claim 7, 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 2.3-3, and a residual magnetic intensity of less than 1nT; the non-magnetic coarse aggregate is pure quartz or limestone with a ferromagnetic content of less than 0.1%, and a residual magnetic intensity of less than 1nT.

10. The non-magnetic concrete according to claim 7, characterized in that: The functional additive is a temperature rise inhibitor or a MgO expansion agent.

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