Photovoltaic support structure design method based on fiber reinforced composite material

Abstract

The invention discloses a photovoltaic support structure design method based on a fiber reinforced composite material, relates to the field of composite material pultruded profile design, can effectively realize photovoltaic support structure calculation adopting a fiber reinforced composite material pultruded profile, and greatly improves design efficiency. According to the method, existing mature general finite element software is fully utilized, the traditional structural mechanics calculation theory is adopted, the strength, stability and deformation of all components of the photovoltaic support are obtained automatically through data post-processing, and the method has high applicability to calculation of the photovoltaic support structure based on the fiber reinforced composite pultruded profile and is suitable for large-scale popularization and application. And the method is suitable for popularization in practical engineering.

Description

Technical Field

[0001] The invention relates to the application field of new materials and new technologies, and in particular to a photovoltaic support structure design method based on fiber-reinforced composite materials. Background Art

[0002] Fiber reinforced composite materials are polymer-based composite materials prepared by composite processes with continuous fibers or fiber fabrics (mainly carbon fibers, glass fibers, and basalt fibers, etc.) as reinforcing phases and polymer resins as matrix phases. They are referred to as composite materials (FRP); structural fiber reinforced composite pultruded profiles are fiber reinforced composite products produced by pultrusion process, with constant cross-sectional shapes, and used as load-bearing structural components. Fiber reinforced composite pultruded profiles have the properties of light weight, high strength, corrosion resistance, good processing performance, and environmental protection. Compared with traditional steel structure photovoltaic brackets, photovoltaic brackets using fiber reinforced composite pultruded profiles can not only reduce the load of the structure itself and save the cost of the bracket foundation, but also save the anti-corrosion cost of traditional steel structure photovoltaic brackets. It has important promotion significance in application scenarios such as roof photovoltaics, offshore photovoltaics, and mountain photovoltaics. Therefore, it is necessary to continue to strengthen the technical research and development and application promotion of fiber reinforced composite pultruded profile structural design.

[0003] At present, photovoltaic brackets made of fiber-reinforced composite pultruded profiles are mostly used for roof photovoltaics. The inclination angle and corresponding wind load are small. The selection of photovoltaic bracket structure mainly depends on the manufacturer's experience and short-term load tests, and lacks a complete theoretical calculation as a structural safety brace. The photovoltaic bracket structure mainly includes four parts: purlins, diagonal beams, columns and diagonal braces. The connection relationship is as follows: Figure 1 As shown in the figure, the vertical long and short legs are columns, the diagonal beams are diagonal beams on top of the columns, the horizontal ones in the east-west direction are purlins, and the front and rear columns and diagonal beams are directly connected to the front and rear diagonal braces, which are connected by node connectors and bolts. The purlins are bidirectional bending members, the diagonal braces are axial force members, and the diagonal beams and columns are tension-compression-bending members. The structural stress states are diverse, but the fiber-reinforced composite pultruded profiles are anisotropic materials, and the various mechanical performance indicators are not the same, making the calculation of the photovoltaic bracket structure complicated. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a photovoltaic bracket structure design method based on fiber-reinforced composite materials. Combined with actual engineering applications, the design calculation methods and control points of each bracket component are respectively explained, and a comprehensive and complete design method is proposed to solve the safety and reliability problems of this new material structure.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a photovoltaic support structure design method based on fiber reinforced composite materials, comprising the following steps:

[0006] Step S1, using PVSAP software to establish a photovoltaic support structure model using fiber-reinforced composite pultruded profiles, the photovoltaic support structure includes purlins, diagonal beams, columns and diagonal braces, and various working loads are applied to the purlins;

[0007] Step S2, using Sap2000 software to perform structural mechanics calculations on the photovoltaic support structure in step S1 using basic load combination conditions, thereby obtaining the axial force, bending moment and shear force values ​​of purlins, diagonal beams, columns and diagonal braces under different loads; using the SAP2000 model to calculate the internal force of the photovoltaic support structure;

[0008] Step S3, in combination with existing relevant provisions and documents, a standardized calculation table is compiled to improve the calculation of the design value of the bearing capacity of purlins, diagonal beams, columns and diagonal braces, and the bearing capacity of the purlins, diagonal beams, columns and diagonal braces obtained in step S2 is verified item by item;

[0009] Step S4, using the SAP2000 model to perform structural mechanics calculations on the photovoltaic support structure in step S1 using a standard load combination condition, and obtaining vertical bending deformation values ​​and vertical shear deformation values ​​of purlins and diagonal beams under different loads;

[0010] Step S5, combining existing standard documents, compiling standardized calculation tables, and verifying the vertical bending deformation values ​​and vertical shear deformation values ​​of the purlins and diagonal beams obtained in step S4 item by item;

[0011] Step S6, using the SAP2000 model to perform structural calculation on the photovoltaic support structure in step S1 using a standard load combination to obtain a horizontal displacement deformation value of the column top;

[0012] Step S7, combining existing standard documents, compiling a standardized calculation table, and verifying the horizontal displacement deformation value of the column top obtained in step S6.

[0013] A further improvement of the technical solution of the present invention is that: in the step S1, the dimensions of the purlins, diagonal beams, columns and diagonal braces of the photovoltaic support structure are preset in combination with the external dimensions, layout scheme and dimensions of the photovoltaic modules of the photovoltaic support structure, and the geometric calculation model of the photovoltaic support structure is established using the PVSAP software; various working loads are applied to the purlins in combination with the inclination angle of the photovoltaic support structure, the weight of the photovoltaic modules and the meteorological data of the location of the photovoltaic support structure.

[0014] A further improvement of the technical solution of the present invention is that: in the step S1, the columns and diagonal beams in the photovoltaic support components are tension-compression-bending components, the purlins are bidirectional bending components, the diagonal braces are axially force-bearing components, the purlins, diagonal beams and columns adopt rectangular tube cross-sections; the diagonal braces adopt groove cross-sections.

[0015] A further improvement of the technical solution of the present invention is that: in the step S3, in combination with the relevant provisions of the "Technical Code for Composite Pultrusion Profile Structure", "Design Code for Photovoltaic Support Structure" and "Steel Structure Design Standard", a standardized calculation table is compiled to verify the bearing capacity of purlins, diagonal beams, columns and diagonal braces under the basic load combination conditions. If the bearing capacity of any component of the purlins, diagonal beams, columns and diagonal braces is not met, the cross-sectional size of the corresponding component of the photovoltaic support structure model in step S1 needs to be increased, with each increase being 5mm to 20mm, and the above steps S2 to S3 are repeated until the calculation results meet the requirements.

[0016] The further improvement of the technical solution of the present invention lies in that: the standardized calculation table in step S3 clearly distinguishes the calculation formulas for the bending, shear strength and overall stability of the purlins to the strong axis and weak axis respectively; clearly distinguishes the calculation formulas for the design values ​​of the local buckling axial compressive bearing capacity of the web and flange of the diagonal brace respectively; clearly distinguishes the calculation formulas for the design values ​​of the local buckling axial compressive bearing capacity of the web and flange of the column, diagonal beam and purlin respectively; and supplements the calculation formulas for the stability calculation of the groove section of the diagonal brace: the slenderness ratio of the section to the z-axis, the equivalent slenderness ratio of the section in the bending-torsional buckling state, the fan moment of inertia of the gross section of the component to the shear center, and the free torsion constant of the gross section of the component to the shear center.

[0017] A further improvement of the technical solution of the present invention is that: in the step S5, in combination with the relevant provisions of the "Technical Code for Composite Pultrusion Profile Structure", "Design Code for Photovoltaic Support Structure" and "Steel Structure Design Standard", a standardized calculation table is compiled to verify the vertical bending deformation value and vertical shear deformation value of the purlin and the diagonal beam under the standard load combination condition. If the vertical bending deformation value and vertical shear deformation value of any component in the purlin and the diagonal beam are not satisfied, the cross-sectional size of the corresponding component of the photovoltaic support structure model in step S1 needs to be increased, with each increase of 5mm to 20mm, and the above steps S2 to S5 are repeated until the calculation result meets the requirements.

[0018] A further improvement of the technical solution of the present invention is that the standardized calculation table in step S5 clearly defines the vertical bending deformation design value and the vertical shear deformation design value of the purlin and the diagonal beam under the standard load combination condition, and the vertical bending deformation design value and the vertical shear deformation design value take into account the deformation magnification factor corresponding to the 25-year service life.

[0019] A further improvement of the technical solution of the present invention is that: in the step S7, in combination with the relevant provisions of the "Technical Code for Composite Pultrusion Profile Structure", "Design Code for Photovoltaic Support Structure" and "Steel Structure Design Standard", a standardized calculation table is compiled, and the horizontal displacement deformation value of the top of the front column and the horizontal displacement deformation value of the top of the rear column under the standard load combination condition are verified item by item. If the horizontal displacement deformation value of the top of the front column and the horizontal displacement deformation value of the top of the rear column are not satisfied, the cross-sectional size of the corresponding component of the photovoltaic support structure model in step S1 needs to be increased, with each increase of 5mm to 20mm, and the above steps S2 to S7 are repeated until the calculation result meets the requirements.

[0020] A further improvement of the technical solution of the present invention is that the standardized calculation table in step S7 clearly defines the design value of the horizontal displacement of the top of the front column and the design value of the horizontal displacement of the top of the rear column under the standard load combination condition, and the design value of the horizontal displacement of the top of the front column and the design value of the horizontal displacement of the top of the rear column take into account the deformation amplification factor corresponding to a service life of 25 years.

[0021] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is:

[0022] 1. The design method proposed in the present invention can effectively realize the structural calculation of photovoltaic brackets made of fiber-reinforced composite pultruded profiles, greatly improving the design efficiency. It not only makes full use of the existing mature general finite element software, but also adopts the traditional structural mechanics calculation theory. Through data post-processing, the strength, stability and deformation of each component of the photovoltaic bracket are obtained. It has strong applicability to the calculation of photovoltaic bracket structures based on fiber-reinforced composite pultruded profiles, and is suitable for promotion in actual engineering.

[0023] 2. In step S1, the present invention uses PVSAP software to establish a geometric calculation model of a photovoltaic support structure using fiber-reinforced composite pultruded profiles, and applies various working loads on the purlins, providing basic conditions for structural calculation;

[0024] 3. In the present invention, in steps S2-S3, the internal forces of the photovoltaic support component structure are calculated by combining the SAP2000 model, and the calculation of the design value of the component bearing capacity is improved by using a standardized calculation table; in addition, the calculation formulas M for the bending strength, shear strength and overall stability of the bidirectional bending component (purlin) to the strong axis and weak axis are clearly distinguished. rx 、M ry 、M cr1x 、M cr1y 、V rx 、V ry、 V crx 、V cry; Clearly distinguish the calculation formulas for the design values ​​of the axial compressive bearing capacity of the web and flange for local buckling of axial compressive components (columns, diagonal beams and purlins) respectively cr2x 、N cr2y ; Clearly distinguish the calculation formulas M for the design value of the axial compressive bearing capacity of the web and flange for the local buckling of the bending member (bracing) cr2x 、M cr2y ; Supplemented the stability calculation of the channel section involving the slenderness ratio λ of the section to the z-axis (perpendicular to the section direction) z , equivalent slenderness ratio λ of section in flexural-torsional buckling state yz , Sectoral moment of inertia of the gross section of the component to the shear center (mm 6 )I w , the free torsion constant I of the gross section of the member about the shear center t Parameter calculation formula:

[0025] 4. In steps S4-S5, the present invention calculates the vertical bending deformation of the purlin and the diagonal beam in combination with the SAP2000 model, uses a standardized calculation table to improve the shear deformation values ​​of the purlin and the diagonal beam, and considers the deformation amplification factor corresponding to the 25-year service life to complete the vertical deformation verification of the purlin and the diagonal beam;

[0026] 5. In steps S6-S7, the present invention combines the SAP2000 model to calculate the horizontal displacement of the column top, and considers the deformation amplification factor corresponding to the 25-year service life to complete the horizontal deformation verification of the bracket. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a geometric calculation model diagram of a photovoltaic support structure using fiber-reinforced composite material pultruded profiles established by the present invention using PVSAP software;

[0028] Figure 2 This is the self-weight load application diagram of working condition 1 of embodiment 1 of the present invention;

[0029] Figure 3 is a snow load application diagram for working condition 2 of embodiment 1 of the present invention;

[0030] Figure 4 This is a frontal wind load application diagram for working condition 3 of embodiment 1 of the present invention;

[0031] Figure 5 This is a diagram of the application of wind load from the back side in working condition 4 of embodiment 1 of the present invention;

[0032] Among them, 1. purlins, 2. diagonal beams, 3. columns, 4. diagonal braces, 5. top plate. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with embodiments:

[0034] A photovoltaic support structure design method based on fiber reinforced composite materials includes the following steps:

[0035] Step S1: Combine the external dimensions, layout scheme and dimensions of photovoltaic support structure, preset the dimensions of purlin 1, diagonal beam 2, column 3 and diagonal brace 4 of photovoltaic support structure, and establish the geometric calculation model of photovoltaic support structure using fiber reinforced composite pultruded profile by using PVSAP software, such as Figure 1 As shown, the photovoltaic support structure includes purlins 1, diagonal beams 2, columns 3 and diagonal braces 4. The columns 3 and diagonal beams 2 in the photovoltaic support components are tension-compression-bending components, the purlin 1 is a bidirectional bending component, and the diagonal brace 4 is an axial force-bearing component. The purlins 1, diagonal beams 2, and columns 3 adopt rectangular tube cross-sections; the diagonal brace 4 adopts a groove cross-section.

[0036] Combined with the inclination angle of the photovoltaic support structure, the weight of the photovoltaic module and the meteorological data of the location of the photovoltaic support structure, various working loads are applied to the purlin 1. In step S1, the present invention uses PVSAP software to establish a geometric calculation model of the photovoltaic support structure using fiber-reinforced composite pultruded profiles, and applies various working loads on the purlin, providing basic conditions for structural calculation.

[0037] Step S2, using Sap2000 software to perform structural mechanics calculations on the photovoltaic support structure in step S1 using the basic load combination conditions, thereby obtaining the axial force, bending moment and shear force values ​​of the purlin 1, diagonal beam 2, column 3 and diagonal brace 4 under different loads; using the SAP2000 model to calculate the internal force of the photovoltaic support structure. The calculation process is as follows:

[0038] (1) Verification of axially tensioned members:

[0039] Where N is the design value of the axial force borne by the component; N T —Design value of axial tensile bearing capacity; k—effective section reduction factor, where the reduction factor is 0.7 for sections with holes and 1.0 for sections without holes; A n —Net cross-sectional area of ​​the member; f L T ,d Design value of longitudinal tensile strength;

[0040] (2) Verification of axially compressed members: N≤N c =min(N s ,N cr1 ,N cr2 )

[0041] 1) Rectangular tube section:

[0042] ①

[0043] ② Design value of local stable compressive bearing capacity of web:

[0044] ③Design value of local stable compressive bearing capacity of flange:

[0045] Where N is the design value of the axial force borne by the component (N); c —Design value of axial tensile bearing capacity (N); N s —Design value of the ultimate bearing capacity of the full-section compressive material failure of the component (N); N cr1 —Design value of the overall stability ultimate bearing capacity of the component (N); N cr2 (N cr2x 、N cr2y )—design value of local stable axial compressive bearing capacity of the component (strong axis, weak axis) (N); Design value of longitudinal compressive strength (MPa); A g —Full cross-sectional area of ​​the component (mm 2 );E L c —Longitudinal compressive elastic modulus (MPa); E T c —Transverse compressive elastic modulus (MPa); υ LT —In-plane Poisson's ratio 0.3; G LT —In-plane shear modulus (MPa); β w —web height-to-thickness ratio; β f — flange width-to-thickness ratio;

[0046] 2) Channel section:

[0047] ①

[0048] ②

[0049] ③

[0050] ④ Local stability of flange:

[0051] ⑤ Local stability of the web:

[0052]

[0053]

[0054] Where N is the design value of the axial force borne by the component (N); c —Design value of axial tensile bearing capacity (N); N s—Design value of the ultimate bearing capacity of the full-section compressive material failure of the component (N); N cr1 —Design value of the overall stability ultimate bearing capacity of the component (N); N cr2 (N cr2x 、N cr2y )—design value of local stability ultimate bearing capacity of component (web, flange) (N); Design value of longitudinal compressive strength (MPa); A g —Full cross-sectional area of ​​the component (mm 2 );E L c —Longitudinal compressive elastic modulus (MPa); E T c —Transverse compressive elastic modulus (MPa); υ LT —In-plane Poisson's ratio 0.3; G LT —In-plane shear modulus (MPa); β w —web height-to-thickness ratio; y p —Distance from the centroid of the cross section to the shear center (mm); R p —Polar radius of gyration of the cross section to the shear center (mm); I0—Polar moment of inertia of the gross cross section of the component to the shear center (mm 4 );I t —Free torsion constant of the gross section of the member about the shear center (mm 4 );I w —Fan moment of inertia of the gross section of the component about the shear center (mm 6 );l w —Calculation length of torsional buckling (mm); λ yz —Equivalent slenderness ratio of the cross section in flexural-torsional buckling state; λ y , z —The slenderness ratio of the cross section to the y-axis and z-axis (perpendicular to the cross section direction); f cry —Bending buckling stress around the y-axis (MPa); f crz —torsional buckling stress around the z-axis (perpendicular to the cross-sectional direction) (MPa); H—constant (mm); D J —Cross-section torsional stiffness (N*mm 4 );D w —Sectional warping stiffness (N*mm 4 ).

[0055] Step S3, in combination with the existing relevant provisions and documents: "Technical Code for Composite Pultrusion Profile Structure", "Design Code for Photovoltaic Support Structure" and "Steel Structure Design Standard", prepare standardized calculation tables, improve the calculation of the design value of the bearing capacity of purlin 1, diagonal beam 2, column 3 and diagonal brace 4, and verify the bearing capacity of purlin 1, diagonal beam 2, column 3 and diagonal brace 4 obtained in step S2 item by item. If the bearing capacity of any component of purlin 1, diagonal beam 2, column 3 and diagonal brace 4 is not satisfied, the cross-sectional size of the corresponding component of the photovoltaic support structure model in step S1 needs to be increased, with each increase of 5mm to 20mm, and repeat the above steps S2 to S3 until the calculation results meet the requirements. The verification process is as follows:

[0056] (1) Calculation of bending bearing capacity of bending shear members (purlins): M≤M c =min(M r ,M cr1 ,M cr2 )

[0057] ① Strong axis bending bearing capacity:

[0058] ②Bending bearing capacity of weak axis:

[0059] ③ Design value of overall stable bending bearing capacity under strong axis bending

[0060] ④ Design value of overall stable bending bearing capacity under weak axis bending

[0061] ⑤ Design value of flange local buckling stability bending bearing capacity

[0062] ⑥ Design value of local buckling stability bending bearing capacity of web

[0063]

[0064] (The cantilever section takes the value 1.0)

[0065] When the compression flange buckles locally,

[0066]

[0067] When the web buckles locally,

[0068] Wherein, M is the design value of the bending moment borne by the member (kN*m); c —Design value of bending bearing capacity (kN*m); M r—Design value of bending bearing capacity when material failure occurs (kN*m); M cr1 (M cr1x 、M cr1y )—design value of the overall stability (strong axis, weak axis) bending bearing capacity of the component (kN*m); M cr2 (M cr2x 、M cr2y )—design value of the local stability (strong axis, weak axis) bending bearing capacity of the component (kN*m); f L,d —Design value of longitudinal strength of component (MPa); x ,I y ——The moment of inertia of the component section around the x-axis (strong axis) and y-axis (weak axis) (mm 4 ); x, y—the distance from the neutral axis to the edge fiber of the component (mm); C b —Moment correction factor for unconstrained members with diagonal braces at both ends within the span; L b —The length between the lateral restraint points of the compression flange or the length between two adjacent bracing points that restrain the torsion of the cross section (mm); M1—the absolute value of the bending moment at the 1 / 4 point of the section without bracing (kN*m); M2—the absolute value of the bending moment at the midpoint of the section without bracing (kN*m); M3—the absolute value of the bending moment at the 1 / 3 point of the section without bracing (kN*m); f cr —Design value of critical buckling stress (MPa).

[0069] (2) Calculation of shear bearing capacity of bending and shear members (purlins): V ≤ V c =min(V r ,V cr )

[0070] ① Design value of shear bearing capacity of strong axis web: V ry =0.9A s f LT,d

[0071] ② Design value of shear bearing capacity of weak axis flange: V rx =0.9A f f LT,d

[0072] ③ Design value of shear buckling bearing capacity of strong axis web:

[0073] ④ Design value of shear buckling bearing capacity of weak axis flange:

[0074] when hour,

[0075] when hour,

[0076] Where V is the design value of shear force borne by the member (kN); V c — Design value of shear bearing capacity (kN*m); V r (V ry 、V rx )—design value of shear bearing capacity (strong axis, weak axis) where material failure occurs (kN*m); V cr (V ry 、V rx )—(web, flange) shear buckling bearing capacity design value (kN*m); A s —Weight plate area (mm) 2 );A f —Flange area (mm) 2 );f LT，d —Design value of in-plane shear strength (MPa); β w —web height-to-thickness ratio; β f —flange width-to-thickness ratio; k LT —Shear buckling stiffness coefficient.

[0077] (3) Calculation of bearing capacity of combined load-bearing components: N / N c +M x / M x,c +M y / M y,c ≤1.0

[0078] Where N is the design value of the axial force borne by the component (N); c —Design value of axial tensile bearing capacity (N); M x —Design value of bending moment around strong axis (kN*m); M x，c —Design value of bending bearing capacity around strong axis (kN*m); M y —Design value of bending moment around weak axis (kN*m); M y，c —Design value of bending capacity around the weak axis (kN*m).

[0079] In the present invention, in steps S2-S3, the internal force of the photovoltaic support component structure is calculated by combining the SAP2000 model, and the calculation of the design value of the component bearing capacity is improved by using a standardized calculation table; in addition, the calculation formula M of the bending strength, shear strength and overall stability of the bidirectional bending component (purlin) to the strong axis and weak axis is clearly distinguished. rx 、M ry 、M cr1x 、M cr1y 、V rx 、V ry 、V crx 、V cry ; Clearly distinguish the calculation formulas for the design values ​​of the axial compressive bearing capacity of the web and flange for local buckling of axial compressive components (columns, diagonal beams and purlins) respectivelycr2x 、N cr2y ; Clearly distinguish the calculation formulas M for the design value of the axial compressive bearing capacity of the web and flange for the local buckling of the bending member (bracing) cr2x 、M cr2y ; Supplemented the stability calculation of the channel section involving the slenderness ratio λ of the section to the z-axis (perpendicular to the section direction) z , equivalent slenderness ratio λ of section in flexural-torsional buckling state yz , Sectoral moment of inertia of the gross section of the component to the shear center (mm 6 )I w , the free torsion constant I of the gross section of the member about the shear center t Parameter calculation formula.

[0080] Step S4: Use the SAP2000 model to perform structural mechanics calculations on the photovoltaic support structure in step S1 using the standard load combination conditions to obtain the vertical bending deformation values ​​and vertical shear deformation values ​​of the purlin 1 and the diagonal beam 2 under different loads. The calculation process is as follows:

[0081] Vertical deformation caused by vertical bending effect:

[0082] Vertical deformation caused by vertical shear effect:

[0083] Total vertical deformation: S V =S d +S s

[0084] E b =E L =min(E L C ,E L T )

[0085] G b =G LT xA s / A

[0086] Among them, E L —Longitudinal elastic modulus (MPa), taking the longitudinal tensile elastic modulus E L T and longitudinal compressive elastic modulus E L C The smaller value of G LT —In-plane shear modulus (MPa); A s —Web cross-sectional area (mm 2 ); A—full cross-sectional area (mm 2 );F v —Standard value of vertical load on beam (N); G b—Full section shear modulus (MPa); L—span or cantilever end length (mm); k 1, k2—coefficient depending on the load type and boundary conditions, see the table below;

[0087] k 1, k2 coefficient value table

[0088] Load types and boundary conditions <![CDATA[k1]]> <![CDATA[k2]]> The cantilever end bears concentrated load 1 / 3 1 The cantilever end bears local load 1 / 8 1 / 2 The beam ends are simply supported, and the mid-span bears concentrated loads 1 / 48 1 / 4 The beam ends are simply supported and fully uniformly loaded. 5 / 384 1 / 8 Beam ends are fixed and fully evenly loaded 1 / 384 1 / 24

[0089] Step S5, in combination with existing standard documents, a standardized calculation table is prepared, and the vertical bending deformation value and the vertical shear deformation value of the purlin 1 and the diagonal beam 2 obtained in step S4 are verified item by item; in step S5, in combination with the relevant provisions of the "Technical Code for Composite Pultrusion Profile Structure", "Design Code for Photovoltaic Support Structure" and "Steel Structure Design Standard", a standardized calculation table is prepared, and the standardized calculation table clarifies the vertical bending deformation design value and the vertical shear deformation design value of the purlin 1 and the diagonal beam 2 under the load standard combination working condition, and the vertical bending deformation value and the vertical shear deformation value of the purlin 1 and the diagonal beam 2 under the load standard combination working condition are verified item by item,

[0090] Design value of vertical allowable deformation of bending members of any span: S Vi / L i ≤1 / 250

[0091] Where: S Vi is the maximum vertical deformation of the i-th span member, where S Vi The deformation should take into account the deformation magnification factor of 1.4 corresponding to the 25-year service life; L i is the calculated span of the i-th span member. For cantilever members, the calculated span can be twice the cantilever length.

[0092] If the vertical bending deformation value and vertical shear deformation value of any component in the purlin 1 and the diagonal beam 2 are not satisfied, the cross-sectional size of the corresponding component of the photovoltaic support structure model in step S1 needs to be increased, with each increase being 5mm to 20mm, and the above steps S2 to S5 are repeated until the calculation results meet the requirements.

[0093] Step S6, using the SAP2000 model to perform structural calculation on the photovoltaic support structure in step S1 using a standard load combination, and the software automatically obtains the horizontal displacement deformation value of the top of the three front columns and the horizontal displacement deformation value of the top of the three rear columns;

[0094] Step S7, in combination with existing standard documents, prepare a standardized calculation table, and verify the horizontal displacement deformation value of the top of column 3 obtained in step S6. In step S7, in combination with the relevant provisions of the "Technical Code for Composite Pultrusion Profile Structures", "Photovoltaic Support Structure Design Code" and "Steel Structure Design Standard", a standardized calculation table is prepared, which clarifies the design displacement value of the top of the front column 3 and the design displacement value of the top of the rear column 3 under the standard load combination working condition. The horizontal displacement deformation value of the top of the front column 3 and the horizontal displacement deformation value of the top of the rear column 3 under the standard load combination working condition are verified item by item, and the verification process is as follows:

[0095] Displacement verification of the design value of horizontal displacement of the top of the front column 3 and the rear column 3:

[0096] S H / H≤1 / 60

[0097] Where: S H is the horizontal displacement of the top of column 3, where S H It is necessary to consider the deformation magnification factor of 1.4 corresponding to the 25-year service life; H is the height of the top of column 3.

[0098] If the horizontal displacement of the top of the front column 3 and the horizontal displacement of the top of the rear column 3 are not satisfied, the cross-sectional dimensions of the corresponding components of the photovoltaic support structure model in step S1 need to be increased by 5mm to 20mm each time, and the above steps S2 to S7 are repeated until the calculation results meet the requirements. The standardized calculation table in step S7 specifies the design values ​​of the horizontal displacement of the top of the front column 3 and the design values ​​of the horizontal displacement of the top of the rear column 3 under the standard load combination conditions. The design values ​​of the horizontal displacement of the top of the front column 3 and the design values ​​of the horizontal displacement of the top of the rear column 3 take into account the deformation amplification factor corresponding to the 25-year service life.

[0099] Example 1

[0100] The present invention takes a 400,000-kilowatt photovoltaic project in a certain place in China as an example. The project is a Gobi Desert double-column photovoltaic bracket with a component size of 2278mmx1134mmx30mm, a component weight of 31.8kg, an inclination angle of 32 degrees, a 2x13 longitudinal two-arrangement scheme, a horizontal column spacing of 3.475m, and a photovoltaic bracket using a glass fiber reinforced composite pultruded profile.

[0101] Photovoltaic support calculations are modeled using PVSAP software to calculate the internal forces of the support structure under the effects of constant loads, wind loads, snow loads, etc., and the most unfavorable combined working condition internal forces are selected for structural calculations based on the actual stress state of different components to obtain the component bearing capacity and deformation value. The specific steps are as follows:

[0102] Step 1: Use PVSAP software to establish a calculation model, such as Figure 1 The cross-sectional dimensions of the purlins, diagonal beams, supports and columns are predetermined, among which the diagonal beams, purlins and columns are all rectangular tubes 100mmx50mmx5mm (height x width x thickness), and the supports are trough-shaped 100mmx60mmx5mm (height x width x thickness), and the materials are all M30 grade.

[0103] According to the weight of the components and the meteorological data of the project location (basic wind pressure once in 25 years is 0.33kN / mm 2 And basic snow pressure 0.19kN / mm 2 ), apply dead load, wind load and snow load on the purlin, and the corresponding load arrangement diagram is shown in Figure 2-Figure 5 .

[0104] Figures 2 to 5 The intersections of the top plate of the photovoltaic bracket and the purlin 1 are the load application points. Figure 2 The single point load in the figure is 0.078 kN, vertically downward; Figure 3 The single point load in the figure is 0.099 kN, vertically downward; Figure 4 The single point load in the vertical direction is 0.190 kN downward and 0.119 kN from front to back; Figure 5 The single point load in the vertical direction is 0.244 kN and from back to front is 0.152 kN.

[0105] Step 2: Start the SAP2000 program, use the basic load combination to perform structural calculations on the photovoltaic support structure in step 1, and obtain the design value of the controlled internal force of each rod, as shown in Table 1 below:

[0106] Table 1: Design values ​​of internal forces of photovoltaic support components

[0107]

[0108] Step 3: In combination with the relevant provisions of "Technical Code for Composite Pultruded Profile Structure" T / CECS 692-2020, "Design Code for Photovoltaic Support Structure" NB / T 10115-2018 and "Steel Structure Design Standard" GB 50017-2017, prepare standardized calculation tables, and check the purlin 1, inclined beam 2, column 3 and support 4 item by item. The results are shown in Table 2 below.

[0109] Table 2: Design values ​​of bearing capacity of photovoltaic support components

[0110]

[0111]

[0112] Checking the bearing capacity of purlin 1: Vx = 0.558 kN < min(23.14, 52.79) = 23.14 kN, requirements are met;

[0113] Vy = 2.3798 kN < min(9.26, 84.47) = 9.26 kN, requirements are met;

[0114] Mx = 1.436 kN < min(5.35, 5.14, 13.29) = 5.14 kN, requirements are met;

[0115] My = 0.288 kN < min(3.47, 3.42, 10.7) = 3.42 kN, requirements are met;

[0116] Checking the bearing capacity of inclined beam 2: Vx = 1.7 kN < min(23.14, 52.79) = 23.14 kN, requirements are met;

[0117] Vy = 5.105 kN < min(9.26, 84.47) = 9.26 kN, requirements are met;

[0118] Mx = 1.619 kN < min(5.35, 5.14, 13.29) = 5.14 kN, requirements are met;

[0119] N = 1.966 kN < min(128.5, 12.52, 64.15, 16.04) = 12.52 kN, requirements are met;

[0120] Checking the combined internal forces of inclined beam 2: Mx / Mc + N / Nc = 1.619 / 5.14 + 1.966 / 12.52 = 0.472 < 1.0, requirements are met;

[0121] Checking the bearing capacity of column 3: Vy = 0.421 kN < min(9.26, 84.47) = 9.26 kN, requirements are met;

[0122] Mx = 0.461 kN < min(5.35, 5.14, 13.29) = 5.14 kN, requirements are met;

[0123] N = 9.59 kN < min(128.5, 12.52, 64.15, 16.04) = 12.52 kN, requirements are met;

[0124] Checking the combined internal forces of column 3: Mx / Mc + N / Nc = 0.461 / 5.14 + 9.59 / 12.52 = 0.86 < 1.0, requirements are met;

[0125] Check of the bearing capacity of the diagonal brace 4: N = 8.445 kN < min(91.8, 10.62, 10, 14.85) = 10 kN, requirements are met;

[0126] Step 4: Start the SAP2000 program, perform structural calculations on the PV support structure in Step 1 using the standard combination of loads, and obtain the vertical bending deformation values of the diagonal beams and purlins, as shown in Table 3 below:

[0127] Table 3: Vertical bending deformation values of diagonal beams and purlins

[0128]

[0129] Remark: The vertical bending deformation under the standard combination uniformly considers a magnification factor of 1.4.

[0130] Table 4: Vertical shear deformation values of diagonal beams and purlins

[0131]

[0132] Remark: The vertical shear deformation under the standard combination uniformly considers a magnification factor of 1.4.

[0133] Step 5: In combination with the relevant provisions of the "Technical Specification for Pultruded Composite Profiles Structures" T / CECS 692-2020, the "Design Specification for PV Support Structures" NB / T 10115-2018, and the "Standard for Design of Steel Structures" GB 50017-2017, check the vertical deformations of the purlins and diagonal beams item by item, and the results are as follows.

[0134] The vertical bending deformation value of purlin 1: 0.356 + 0.0027 = 0.36 mm < 3475 / 250 = 13.9 mm, requirements are met;

[0135] The vertical bending deformation value of diagonal beam 2: 0.117 + 0.0046 = 0.12 mm < 2600 / 250 = 10.4 mm, requirements are met;

[0136] Step 6: Start the SAP2000 program, perform structural calculations on the PV support structure in Step 1 using the standard combination of loads, and obtain the horizontal deformation value at the top of the support columns, as shown below:

[0137] Displacement at the top of the front column 3: S h = 1.146 mm

[0138] Displacement at the top of the rear column 3: S h = 1.23 mm

[0139] Step 7: In combination with the relevant provisions of the "Technical Code for Composite Pultruded Profile Structures" T / CECS 692-2020, the "Design Code for Photovoltaic Support Structures" NB / T 10115-2018 and the "Steel Structure Design Standard" GB 50017-2017, the horizontal deformation of the support column top is verified, and the results are shown below.

[0140] Front column 3 top displacement: S h =1.146mm<1154 / 250=4.62mm

[0141] Rear pillar 3 top displacement: S h =1.23mm<2278 / 250=9.112mm

[0142] In summary, the photovoltaic support structure made of fiber-reinforced composite pultruded profiles used in a local photovoltaic project in China meets the requirements for safe structural use.

Claims

1. A photovoltaic support structure design method based on fiber reinforced composite materials, characterized in that: The steps include: Step S1, using PVSAP software to establish a geometric calculation model of a photovoltaic support structure using a fiber-reinforced composite pultruded profile, the photovoltaic support structure comprising a purlin (1), an inclined beam (2), a column (3) and an inclined brace (4), and applying various working loads to the purlin (1); Step S2, using Sap2000 software to perform structural mechanics calculations on the photovoltaic support structure in step S1 using basic load combination conditions, thereby obtaining the axial force, bending moment and shear force values ​​of the purlin (1), the diagonal beam (2), the column (3) and the diagonal brace (4) under different loads; and using the SAP2000 model to calculate the internal force of the photovoltaic support structure; Step S3, combining existing relevant provisions and documents, compiling a standardized calculation table, improving the calculation of the design value of the bearing capacity of the purlin (1), the inclined beam (2), the column (3) and the diagonal brace (4), and verifying the bearing capacity of the purlin (1), the inclined beam (2), the column (3) and the diagonal brace (4) obtained in step S2 item by item; Step S4, using the SAP2000 model to perform structural mechanics calculations on the photovoltaic support structure in step S1 using a standard load combination condition, and obtaining vertical bending deformation values ​​and vertical shear deformation values ​​of the purlin (1) and the diagonal beam (2) under different loads; Step S5, combining existing standard documents, compiling a standardized calculation table, and verifying the vertical bending deformation value and the vertical shear deformation value of the purlin (1) and the diagonal beam (2) obtained in step S4 item by item; Step S6, using the SAP2000 model to perform structural calculation on the photovoltaic support structure in step S1 using a standard load combination to obtain a horizontal displacement deformation value of the top of the column (3); Step S7: In combination with existing standard documents, a standardized calculation table is compiled to verify the horizontal displacement deformation value of the top of the column (3) obtained in step S6.

2. The photovoltaic support structure design method based on fiber reinforced composite materials according to claim 1, characterized in that: In step S1, the dimensions of the purlins (1), diagonal beams (2), columns (3) and diagonal braces (4) of the photovoltaic support structure are preset in combination with the external dimensions of the photovoltaic support structure, the layout scheme and the dimensions of the photovoltaic modules, and a geometric calculation model of the photovoltaic support structure is established using PVSAP software; various working loads are applied to the purlins (1) in combination with the inclination angle of the photovoltaic support structure, the weight of the photovoltaic modules and the meteorological data of the location of the photovoltaic support structure.

3. The photovoltaic support structure design method based on fiber reinforced composite materials according to claim 1, characterized in that: In the step S1, the columns (3) and diagonal beams (2) in the photovoltaic support components are tension-compression-bending components, the purlins (1) are bidirectional bending components, and the diagonal braces (4) are axial force-bearing components. The purlins (1), diagonal beams (2), and columns (3) have rectangular tube cross-sections; and the diagonal braces (4) have groove cross-sections.

4. The photovoltaic support structure design method based on fiber reinforced composite materials according to claim 3 is characterized in that: In step S3, a standardized calculation table is compiled in combination with the relevant provisions of the "Technical Code for Composite Pultruded Profile Structures", "Design Code for Photovoltaic Support Structures" and "Steel Structure Design Standards", and the bearing capacity of the purlin (1), the inclined beam (2), the column (3) and the diagonal brace (4) under the basic load combination working condition is verified item by item. If the bearing capacity of any component among the purlin (1), the inclined beam (2), the column (3) and the diagonal brace (4) does not meet the requirements, the cross-sectional size of the corresponding component of the photovoltaic support structure model in step S1 needs to be increased, and the increase each time is 5 mm to 20 mm, and the above steps S2 to S3 are repeated until the calculation result meets the requirements.

5. The photovoltaic support structure design method based on fiber reinforced composite materials according to claim 4, characterized in that: The standardized calculation table in step S3 clearly distinguishes the calculation formulas for the bending strength, shear strength and overall stability of the purlin (1) for the strong axis and weak axis respectively; clearly distinguishes the calculation formulas for the design values ​​of the local buckling axial compressive bearing capacity of the web and flange of the diagonal brace (4); clearly distinguishes the calculation formulas for the design values ​​of the local buckling axial compressive bearing capacity of the web and flange of the column (3), the diagonal beam (2) and the purlin (1); and supplements the calculation formulas for the four parameters required for the stability calculation of the channel section of the diagonal brace (4): the slenderness ratio of the section to the z-axis, the equivalent slenderness ratio of the section in the bending-torsional buckling state, the fan-shaped moment of inertia of the gross section of the component to the shear center, and the free torsion constant of the gross section of the component to the shear center.

6. The photovoltaic support structure design method based on fiber reinforced composite materials according to claim 1, characterized in that: In step S5, a standardized calculation table is compiled in combination with the relevant provisions of the "Technical Code for Composite Pultrusion Profile Structure", "Design Code for Photovoltaic Support Structure" and "Steel Structure Design Standard", and the vertical bending deformation value and the vertical shear deformation value of the purlin (1) and the diagonal beam (2) under the load standard combination working condition are verified item by item. If the vertical bending deformation value and the vertical shear deformation value of any component of the purlin (1) and the diagonal beam (2) do not meet the requirements, the cross-sectional size of the corresponding component of the photovoltaic support structure model in step S1 needs to be increased, and the increase each time is 5mm to 20mm, and the above steps S2 to S5 are repeated until the calculation result meets the requirements.

7. The photovoltaic support structure design method based on fiber reinforced composite materials according to claim 6, characterized in that: The standardized calculation table in step S5 specifies the vertical bending deformation design value and the vertical shear deformation design value of the purlin (1) and the diagonal beam (2) under the standard load combination working condition, and the vertical bending deformation design value and the vertical shear deformation design value take into account the deformation magnification factor corresponding to the service life of 25 years.

8. The photovoltaic support structure design method based on fiber reinforced composite materials according to claim 1, characterized in that: In step S7, in combination with the relevant provisions of the "Technical Code for Composite Pultrusion Profile Structure", "Design Code for Photovoltaic Support Structure" and "Steel Structure Design Standard", a standardized calculation table is compiled to verify the horizontal displacement deformation value of the top of the front column (3) and the horizontal displacement deformation value of the top of the rear column (3) under the load standard combination working condition. If the horizontal displacement deformation value of the top of the front column (3) and the horizontal displacement deformation value of the top of the rear column (3) do not meet the requirements, the cross-sectional size of the corresponding component of the photovoltaic support structure model in step S1 needs to be increased, with each increase being 5 mm to 20 mm, and the above steps S2 to S7 are repeated until the calculation results meet the requirements.

9. A photovoltaic support structure design method based on fiber reinforced composite materials according to claim 8, characterized in that: The standardized calculation table in step S7 specifies the design value of the horizontal displacement of the top of the front column (3) and the design value of the horizontal displacement of the top of the rear column (3) under the load standard combination working condition. The design value of the horizontal displacement of the top of the front column (3) and the design value of the horizontal displacement of the top of the rear column (3) take into account the deformation magnification factor corresponding to a service life of 25 years.

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