A direct design method for semi-rigid connection steel frame-braced structures

Abstract

The present application relates to a kind of semi-rigid connection steel frame-support structure direct design method, comprising the following steps: according to load determination frame beam, frame column, plate component section size, and calculate internal force design value;Select bolt type, reasonably arrange the structure of beam-column joint area, to determine the flexural capacity of beam-column joint and the rigidity of each component;Establish the overall model of semi-rigid connection steel frame-support structure, according to the architectural function layout and structure stiffness demand, adjust the stiffness of buckling restrained brace, so that the lateral stiffness of semi-rigid model with increased support in two principal axes direction and the error of original rigid model is less than the set threshold value;Define the nonlinear properties of node, nonlinear working condition and combination, and carry out the checking of semi-rigid connection steel frame-support structure in load-carrying capacity limit state and normal use limit state.Compared with prior art, the present application has the advantages of high bearing efficiency, high section utilization rate, and saving steel quantity under the same mechanical performance.

Description

Technical Field

[0001] The invention relates to a building structure design method, in particular to a direct design method of a semi-rigid connection steel frame-support structure. Background Art

[0002] Semi-rigid joints exhibit stress characteristics intermediate between rigid joints and ideal hinge joints. When used in beam-column connections in steel frame structures, they can withstand both certain bending moments and certain rotational angles. When properly designed, these joints can also exhibit excellent ductility and hysteresis. These characteristics enable properly designed semi-rigid steel frame structures (steel frame structures using semi-rigid beam-column joints) to withstand more balanced loads under vertical loads and exhibit superior deformation capacity under earthquakes, thereby reducing steel consumption.

[0003] The bending stiffness model of semi-rigid joints is often nonlinear, requiring accurate determination of the internal forces of semi-rigid steel frame structures through nonlinear analysis, significantly increasing the complexity of the design process. Consequently, semi-rigid steel frame systems are difficult for engineers to accept and apply in practical projects. Furthermore, semi-rigid steel frame structures exhibit weaker lateral stiffness than rigid-jointed frames, making it difficult to fully utilize the advantages of semi-rigid steel frame systems in order to resist external horizontal forces.

[0004] How to realize the direct design method of semi-rigid connection steel frame-support structure has become a technical problem that needs to be solved. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a scientific, accurate and effective direct design method for semi-rigid connection steel frame-support structure, so as to give full play to the advantages of semi-rigid connection steel frame-support structure such as high load-bearing efficiency, high cross-sectional utilization and good economic benefits.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] According to one aspect of the present invention, a direct design method for a semi-rigid connected steel frame-support structure is provided, the method comprising the following steps:

[0008] Step S1: Determine the cross-sectional dimensions of the frame beams, frame columns, and plate components based on the design load of the semi-rigid connection steel frame-support structure, and calculate the design value of the internal force;

[0009] Step S2: Select the bolt type and optimize the structure of the beam-column joint area to determine the bending bearing capacity of the beam-column joint and the stiffness of each component;

[0010] Step S3: Establish an overall model of the semi-rigid connection steel frame-support structure. According to the building functional layout and structural stiffness requirements, adjust the stiffness of the buckling restraint support so that the error between the lateral stiffness of the semi-rigid model with added supports in the two main axis directions and the original rigid connection model is less than a set threshold.

[0011] Step S4: Define the nonlinear properties of the nodes, nonlinear working conditions and combinations, and perform ultimate limit state and serviceability limit state verification of the semi-rigid connection steel frame-support structure.

[0012] Preferably, the design load of the semi-rigid connection steel frame-support structure includes dead load, wind load, earthquake load in two directions, wind load in two directions and a combination according to load specifications.

[0013] Preferably, in step S1, determining the cross-sectional dimensions of the frame beams, frame columns, and plate components includes:

[0014] Step S101, calculate the axial pressure of the concrete-filled steel tube column caused by the floor load of each floor:

[0015]

[0016]

[0017]

[0018] in, N i For the i Design value of equivalent column axis pressure of floor load, N gk and N qk are the standard values ​​of column axial pressure for dead load and live load, respectively. q s is the equivalent surface load of the floor slab self-weight, q gk and q qk are the standard values ​​of uniformly distributed dead load and live load on the floor, l y and l x Calculate the spans for the slabs parallel and perpendicular to the design beam length directions separately;

[0019] Step S102, calculate the design value of the axial pressure of the concrete-filled steel tube column:

[0020]

[0021] in, N in For the iDesign value of axial pressure of concrete-filled steel tube columns on floors. N i For the i Design value of equivalent column axial pressure of floor load;

[0022] Step S103: Design the cross-section of each layer of concrete-filled steel tube columns according to the following formula:

[0023]

[0024] in, f s is the design value of steel tensile strength, f c is the design value of concrete compressive strength, A s is the cross-sectional area of ​​the steel pipe, A c is the cross-sectional area of ​​concrete in the steel tube.

[0025] Preferably, in step S1, calculating the design value of the internal force includes the following steps:

[0026] Step S104, reinforcing the floor slab;

[0027] Step S105: Calculate the design value of the composite beam bending moment M ;

[0028] Step S106, designing the cross section of the H-shaped steel beam;

[0029] Step S107: Calculate the design value of the beam end shear force V :

[0030] Step S108: Verify whether the shear bearing capacity of the composite beam meets the requirements. ,in, h w is the web height of the steel beam section ，t w is the web thickness of the steel beam section, f y is the steel yield strength of the steel beam; if it meets the requirements, the design meets the requirements. If this step verification cannot meet the requirements, return to step S106 and increase the thickness of the web of the H-shaped steel beam section. t w , redesign the H-beam section.

[0031] More preferably, the calculation of the composite beam bending moment design value is M Specifically:

[0032]

[0033]

[0034]

[0035] wherein, M gk is the standard value of constant load bending moment, M qk is the standard value of live load bending moment, q s is the equivalent surface load of floor self-weight, q gk and q qk are the standard values of floor uniform constant load and live load, respectively, l y and l x are the calculation spans of floor parallel and perpendicular to the design beam length, respectively;

[0036] The calculation beam end shear force design value is specifically:

[0037]

[0038]

[0039]

[0040] wherein, V gk is the standard value of constant load shear force, V qk is the standard value of live load shear force.

[0041] More preferably, in the step S2, the structure of the beam-column joint area comprises the bolt position and quantity of the beam-column joint area, and the thickness of the end plate.

[0042] More preferably, the step S2 comprises:

[0043] Step S201, preset the end plate width equal to the steel beam flange width, preset the type of bolt joint, and check the tensile capacity of the end plate weakened section;

[0044] Step S202, select the type of one-way bolt, and determine the number of one-way bolt;

[0045] Step S203, design the one-way bolt arrangement;

[0046] Step S204, calculate the tensile capacity of each row of one-way bolt, the bending capacity of the end plate, and the tensile capacity of the steel pipe column wall;

[0047] Step S205, calculating the design value of the tensile bearing capacity of the i-th row of bolts, the design value of the tensile bearing capacity of the upper and lower rows of steel bars on the floor slab, the local compressive bearing capacity of the concrete in the steel pipe column, and the compressive yield bearing capacity of the steel pipe column wall web;

[0048] Step S206, solving and calculating the height of the compression zone, determining the number of bolt rows in the tension zone, and calculating the design value of the node negative moment bending bearing capacity;

[0049] Step S207: Verify whether the sum of the design value of the node's negative bending moment flexural bearing capacity and the design value of the composite beam's positive bending moment flexural bearing capacity is greater than the composite beam's bending moment design value; if not, return to step S202, increase the number of one-way bolts, and redesign the node structure; if still not, return to step S106, increase the H-beam cross-section height, and redesign the node structure;

[0050] Step S208, calculating the design value of the local compressive bearing capacity of the floor slab concrete;

[0051] Step S209, calculating the design value of the node positive bending moment bending bearing capacity;

[0052] Step S210: Calculate the stiffness of each component of the node.

[0053] More preferably, the parameters of the one-way bolt include diameter, strength, and specifications;

[0054] In step S204, the tensile strength of the one-way bolts in each row of bolts is calculated. F b , end plate bending bearing capacity F ep and the tensile bearing capacity of the steel pipe column wall F tcf Specifically:

[0055]

[0056]

[0057]

[0058] in, n b The number of one-way bolts contained in each bolt row, N t b is the design value of the tensile bearing capacity of the one-way bolt, n、e w is the calculation parameter, m is the distance between the center line of the bolt hole and the edge of the web of the T-connector, l eff,1is the effective length of the plastic hinge line of the T-connector flange under the first failure mode, E e is the virtual work of the external force on the steel pipe column wall under the tensile load, δ Assuming unit displacement, t f is the thickness of the flange of the T-connector;

[0059] The above-mentioned bearing capacity shall also meet the following requirements:

[0060]

[0061]

[0062] If not, return to step S203 and increase the distance between the center line of the one-way bolt hole and the edge of the web of the T-shaped connector. m , redesign the one-way bolt arrangement; if it still cannot meet the requirements, return to step S201 and increase the end plate width b ep , reduce the thickness of the end plate t ep , redesign the end plate size.

[0063] More preferably, in step S205, the first i Design value of tensile bearing capacity of bolt row F bo,i , Design value of tensile bearing capacity of upper and lower rows of steel bars on floor slabs F tr and F br , Local compressive bearing capacity of concrete in steel tube columns F cc , Steel pipe column wall web compressive yield bearing capacity F cs The specific method is:

[0064]

[0065]

[0066]

[0067]

[0068]

[0069] in, A tr and A br are the total cross-sectional areas of the upper and lower rows of steel bars within the effective width of the floor slab in the negative bending moment area,f ru is the design value of the tensile strength of the steel bar, b cc is the width of the concrete inside the column, f cu is the compressive strength of concrete cube, x ch is the height of the compression zone, t w is the thickness of the web of the rectangular steel tube column;

[0070] In step S206, the height of the pressure zone is calculated. x ch , so the calculation process for determining the number of bolt rows in the tension zone is:

[0071]

[0072] Calculate the design value of the negative moment bending capacity of the node M hu :

[0073]

[0074] in, F bo,it is the design value of the tensile bearing capacity of the tension bolt row, h i is the distance between each row of bolts in the tension zone and the upper flange of the steel beam, is the thickness of the floor slab, h tr is the distance between the upper row of steel bars and the upper edge of the floor slab, h br is the distance between the lower row of steel bars and the lower edge of the floor slab, h b is the cross-sectional height of the H-beam;

[0075] In step S208, the design value of the local compressive bearing capacity of the floor slab concrete is calculated:

[0076]

[0077] in, b cf is the width of the column wall flange, x con is the height of the compression zone of the floor slab, β is the local compressive strength increase coefficient of concrete, f cu is the design value of concrete cube compressive strength;

[0078] In step S209, calculating the design value of the node positive bending moment bending capacity includes:

[0079] Assuming that the neutral axis is displaced within the floor slab, the height of the compression zone of the slab is calculated according to the equation x con :

[0080]

[0081] When satisfied When the neutral axis is inside the floor slab, the design value of the node's positive bending moment bearing capacity is M su Calculate as follows:

[0082]

[0083] If not satisfied , then let x con = h con Substitution F con , calculate the height of the compression zone according to the equation x ch :

[0084]

[0085] At this time, the design value of the node's positive bending moment bending bearing capacity M su Calculate as follows:

[0086]

[0087] in, F bo,it is the design value of the tensile bearing capacity of the tension bolt row, h i is the distance between each row of bolts in the tension zone and the upper flange of the steel beam, is the thickness of the floor slab, x ch is the height of the compression zone, F bo,i For the i Design value of tensile bearing capacity of bolt row, F cc is the local compressive bearing capacity of concrete in the steel tube column, F cs is the compressive yield bearing capacity of the steel pipe column wall web, is the design value of the local compressive bearing capacity of the floor slab concrete.

[0088] Preferably, the node nonlinear properties include node bearing capacity and initial stiffness, and the nonlinear working conditions and their combinations include dead load conditions, live load conditions, x Windward load condition,y Windward load condition, x To earthquake conditions, y directional earthquake conditions, and combinations of these conditions.

[0089] Compared with the prior art, the present invention has the following beneficial effects:

[0090] 1) The present invention designs the interfaces of the beams, columns, and plate components of the semi-rigid steel frame, rationally arranges the parameters of the beam-column node area to determine the bending bearing capacity of the beam-column node, then improves the lateral stiffness by adjusting the buckling restraint support. Finally, the bearing capacity is verified. This realizes the design of the semi-rigid steel frame-support structure, solves the practical engineering application problems currently faced by structural designers for the semi-rigid steel frame system, and can be widely used.

[0091] 2) The present invention compares the designed semi-rigid model with the original rigid-connected model. The supported semi-rigid model shows significant improvements in period and structural lateral displacement compared to the unsupported semi-rigid model. The vertical deflection of the supported semi-rigid connected steel frame beam is greater than that of the rigid-connected steel frame. With the same mechanical properties (i.e., with support), the semi-rigid model saves more than 20% of steel consumption, thus achieving advantages such as high load-bearing efficiency, high cross-sectional utilization, and good economic benefits.

[0092] 3) Compared with the existing design methods of repeated iteration and trial and error, the direct design method of the present invention has simple steps, short design time, high efficiency, and can quickly realize the design and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] Figure 1 Schematic diagram of the flow chart for the direct design method of semi-rigid connected steel frame-support structure;

[0094] Figure 2 Schematic diagram of the semi-rigid connection steel frame-support structure system;

[0095] Figure 3 Schematic diagram of the beam-column joint structure of the semi-rigid connection steel frame-support structure;

[0096] Figure 4 Schematic diagram of the overall model of the semi-rigid connection steel frame-support structure in an embodiment of the present invention;

[0097] In the attached figure, 1: semi-rigid connection steel frame, 2: steel support, 3: frame column, 4: frame beam, 5: end plate and bolts. DETAILED DESCRIPTION

[0098] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0099] This embodiment relates to a direct design method for a semi-rigid connected steel frame-support structure, such as Figure 1 , including the following steps:

[0100] Step S1: Determine the cross-sectional dimensions of the frame beam 4, frame column 3, and plate components according to the design load of the semi-rigid connection steel frame structure, and calculate the design value of the internal force; Figure 2 Schematic diagram of the semi-rigid connection steel frame-support structure system.

[0101] Step S2: Select the bolt type, reasonably arrange the bolt position and quantity, and the end plate thickness in the beam-column joint area to determine the basic parameters of the beam-column joint, such as bending bearing capacity and rotational stiffness, and meet the conceptual design requirements of "strong node, weak component"; the beam-column joint structure is as follows: Figure 3 shown.

[0102] Step S3: Figure 4 Build an overall structural model and, based on the building's functional layout and structural stiffness requirements, arrange buckling-restrained braces to improve lateral stiffness. The specific principle is to adjust the stiffness of the buckling-restrained braces so that the lateral stiffness of the semi-rigid model with added braces in both principal axis directions is roughly equivalent to that of the original rigid-connected model (i.e., a frame structure model where all beam-column joints are rigidly connected).

[0103] Step S4: define the node nonlinear properties (mainly including node bearing capacity and initial stiffness), and define various nonlinear working conditions and their combinations that meet the verification objectives;

[0104] Step S5: Perform calculations on the ultimate bearing capacity state and the serviceability limit state of the structure.

[0105] Specifically, step S1 includes:

[0106] Assuming that the deadweight of the steel beam is 3% to 8% of the total dead load of a single floor, 5% is taken in this case, calculate the axial pressure of the concrete-filled steel tube column caused by the floor load of each floor:

[0107]

[0108]

[0109]

[0110] in,N i For the i Design value of equivalent column axis pressure of floor load, N gk and N qk are the standard values ​​of column axial pressure for dead load and live load, respectively. q s is the equivalent surface load of the floor slab self-weight, q gk and q qk are the standard values ​​of uniformly distributed dead load and live load on the floor, l y and l x Spans are calculated separately for slabs parallel and perpendicular to the design beam length.

[0111] Assuming that the deadweight of the CFST column is 3% to 8% of the total axial pressure of a single layer, and 5% in this case, the design value of the axial pressure of the CFST column is calculated as follows:

[0112]

[0113] in, N in For the i Design value of axial pressure of concrete-filled steel tube columns on floors. N i For the i Design value of equivalent column axial pressure of floor load.

[0114] Design the cross-section of each floor's concrete-filled steel tube column according to the following formula:

[0115]

[0116] in, f s is the design value of steel tensile strength, f c is the design value of concrete compressive strength, A s is the cross-sectional area of ​​the steel pipe, A c is the cross-sectional area of ​​concrete in the steel tube.

[0117] Reinforce the floor slab:

[0118]

[0119] in, ρ is the minimum reinforcement ratio of the floor slab, A ss is the steel bar area per meter of floor slab, h is the floor slab thickness.

[0120] Calculate the design value of the bending moment of the composite beam M :

[0121]

[0122]

[0123]

[0124] in, M gk is the standard value of the dead load bending moment, M qk is the standard value of the live load bending moment, q s is the equivalent surface load of the floor slab self-weight, q qk is the standard value of live load, q gk and q qk are the standard values ​​of uniformly distributed dead load and live load on the floor, l y and l x Spans are calculated separately for slabs parallel and perpendicular to the design beam length.

[0125] Consider the design value of the bending bearing capacity of the composite beam M hb Should not be less than 0.8 M , design the H-shaped steel beam section according to the "Steel Structure Design Standard" GB 50017-2017.

[0126] Calculate the design value of shear force at the beam end:

[0127]

[0128]

[0129]

[0130] in, V gk is the standard value of the dead load shear force, V qk is the standard value of live load shear force.

[0131] (108) Verify the shear bearing capacity of composite beams:

[0132]

[0133] in, h w is the web height of the steel beam section，t w is the web thickness of the steel beam section, f y is the steel yield strength of the steel beam. If this step cannot be satisfied, return to step REF _Ref156225210 \r \h \* MERGEFORMAT (106) and increase the web thickness of the H-beam section. t w , redesign the H-beam section.

[0134] Step S2 specifically includes:

[0135] Preset b ep = b b ,in b ep is the end plate width, b b is the width of the steel beam flange. The preset bolt node uses two rows of one-way bolts to verify the tensile bearing capacity of the weakened section of the end plate:

[0136]

[0137] in, d bb is the diameter of the one-way bolt hole, t ep is the end plate thickness, f y is the steel yield strength of the steel beam.

[0138] Select the type of one-way bolt, including parameters such as diameter, strength, and specifications, and determine the number of one-way bolts. n (Take an even number).

[0139]

[0140] in, and are the design values ​​of the shear and compressive bearing capacity of the one-way bolts, respectively, and are calculated according to the following formula:

[0141]

[0142]

[0143] Where, f vb is the design value of the shear strength of the one-way bolt screw, f vs is the design value of the shear strength of the one-way bolt sleeve, S b is the nominal area of ​​the one-way bolt screw,S s A is the cross-sectional area of the one-way bolt sleeve, d s1 B is the outer diameter of the one-way bolt sleeve, t min C is the smaller value of the thickness of the end plate and the wall thickness of the concrete-filled steel tube column, f c b Fy is the design value of the bearing strength of the bolt.

[0144] The arrangement of the one-way bolts is designed according to the Design Standard for Self-locking One-way High-strength Bolt Connection of Rectangular Steel Tube Members T / CECS 605-2019.

[0145] The tensile bearing capacity of the one-way bolts in each bolt row is calculated F b The bending bearing capacity of the end plate F ep And the tensile bearing capacity of the wall of the steel tube column F tcf :

[0146]

[0147]

[0148]

[0149] Wherein, n b A is the number of one-way bolts contained in each bolt row, N t b Fy is the design value of the tensile bearing capacity of the one-way bolt, n、e w Fy is the calculation parameter, m B is the distance between the center line of the bolt hole and the edge of the web of the T-shaped connecting piece, l eff,1 L is the effective length of the bending plastic hinge line of the flange of the T-shaped connecting piece under the first failure mode, E e W is the virtual work of the external force on the wall of the steel tube column under the action of the tensile load, δ U is the assumed unit displacement, t f T is the thickness of the flange of the T-shaped connecting piece.

[0150] The above bearing capacities should also satisfy:

[0151]

[0152]

[0153] If not, go to step REF _Ref156226228 \r \h \* MERGEFORMAT (203) to increase the distance between the center line of the one-way bolt hole and the edge of the T-shaped connecting piece web m , and redesign the one-way bolt arrangement; if still not, go to step REF _Ref156226242 \r \h \* MERGEFORMAT (201) to increase the width of the end plate b ep , and reduce the thickness of the end plate t ep , and redesign the size of the end plate.

[0154] Calculate the design value of the tensile bearing capacity of the first i row of bolts F bo,i , the design value of the tensile bearing capacity of the upper and lower rows of steel bars on the floor F tr , and F br , the local compressive bearing capacity of the concrete in the steel pipe column F cc , the compressive yield bearing capacity of the wall web of the steel pipe column F cs :

[0155]

[0156]

[0157]

[0158]

[0159]

[0160] wherein, A tr and A br are the total cross-sectional areas of the upper and lower rows of steel bars within the effective width of the floor section in the negative bending moment area, respectively, f ru is the design value of the tensile strength of the steel bar, b cc is the width of the concrete in the column, f cu is the compressive strength of the concrete cube, x ch is the height of the compression zone, t w is the thickness of the wall web of the rectangular steel pipe column.

[0161] Solve the calculation parametersx ch , determine the number of bolt rows in the tension zone:

[0162]

[0163] Calculate the design value of the negative moment bending capacity of the node M hu :

[0164]

[0165] in, F bo,it is the design value of the tensile bearing capacity of the tension bolt row, h i is the distance between each row of bolts in the tension zone and the upper flange of the steel beam, is the thickness of the floor slab, h tr is the distance between the upper row of steel bars and the upper edge of the floor slab, h br is the distance between the lower row of steel bars and the lower edge of the floor slab, h b is the cross-section height of the H-beam.

[0166] Verify the design value of the node's negative moment bending bearing capacity M hu Design value of positive moment bending capacity of composite beam M hb Is the sum greater than the design value of the composite beam bending moment?

[0167]

[0168] in, M is the design value of the composite beam bending moment.

[0169] If not satisfied, return to step REF _Ref156227007 \r \h \* MERGEFORMAT (202), increase the number of one-way bolts, and redesign the node structure; if still not satisfied, return to step REF _Ref156225210 \r \h\* MERGEFORMAT (106), increase the height of the H-beam section h b , redesign the node structure.

[0170] Calculate the design value of local compressive bearing capacity of floor slab concrete:

[0171]

[0172] in, b cf is the width of the column wall flange,x con is the height of the compression zone of the floor slab, β is the concrete local compressive strength increase coefficient (taken as 1.25), f cu is the design value of the compressive strength of concrete cube.

[0173] Calculate the design value of the positive bending moment bearing capacity of the node:

[0174] Assuming that the neutral axis is displaced within the floor slab, the calculation parameters are solved according to the equation x con :

[0175]

[0176] When satisfied When the neutral axis is inside the floor slab, the design value of the node's positive bending moment bearing capacity is M su Calculate as follows:

[0177]

[0178] If not satisfied , then let x con = h con Substitution F con , calculate the height of the compression zone according to the equation x ch :

[0179]

[0180] At this time, the design value of the node's positive bending moment bending bearing capacity M su Calculate as follows:

[0181]

[0182] Calculate the stiffness of each component of the node.

[0183] This embodiment also relates to a design method for a rigidly connected steel frame support structure.

[0184] An actual factory building has a floor plan size of 27 m × 76.5 m, a beam span of 9.0 m horizontally and 8.5 m vertically, and a floor slab thickness of 150 mm. It has three floors, with a ground floor height of 9.0 m and 7.5 m for the second and third floors. The original structure had a partial mezzanine between the second and third floors and a partially exposed machine room on the roof. For ease of calculation, the mezzanine and machine room were simplified.

[0185] The original design adopted a beam-column rigid joint frame structure system. The first-floor frame beams mainly adopted three sections: HN850×300×16×27, HN630×200×15×20 and HN600×200×11×17; the frame columns mainly adopted three sections: square steel tube 500×26 (ground floor), square steel tube 500×20 (second floor) and square steel tube 400×14 (third floor).

[0186] The steel material used is Q355B, with a design strength of 305 MPa, a design shear strength of 175 MPa, and an elastic modulus of 206,000 MPa; the concrete used is C30, with a design compressive strength of 14.3 MPa, a design tensile strength of 1.43 MPa, and an elastic modulus of 30,000 MPa; the steel bar used is HRB400, with a design tensile strength of 360 MPa, a design compressive strength of 360 MPa, and an elastic modulus of 200,000 MPa.

[0187] The building has a design life of 50 years and a safety level of Level 2. Its seismic fortification category is Standard Fortification (C), with a seismic fortification intensity of 7 degrees, a basic earthquake acceleration of 0.10 g, a design earthquake group of Group 2, and a building site category of IV. The basic wind pressure is 0.55 kPa based on a 50-year return period, the ground roughness is Class B, and the wind load shape factor is 1.4.

[0188] The main function of the building is industrial plant. The standard value of floor load is: first floor: dead load: 5 kN / m 2 , live load: 5 kN / m 2 ; Second floor: Dead load: 5 kN / m 2 , live load: 3.5 kN / m 2 ; Third floor: Dead load: 6 kN / m 2 , live load: 3 kN / m 2 .

[0189] The main design loads include: dead load, wind load, earthquake load in two directions, and wind load in two directions, which are combined according to the current load specifications. The X direction refers to the longitudinal axis of the plant model, and the Y direction refers to the transverse axis (i.e., short side) of the plant model.

[0190] The steps of the design method are as follows:

[0191] Step S11: Determine the cross-sectional dimensions of the frame beams and columns as follows:

[0192] First floor column: concrete-filled steel tube column box 300×16;

[0193] Second floor column: Concrete-filled steel tube column box 250×12;

[0194] Third-story column: Steel tube concrete column box 200×10.

[0195] The design results of the frame beam section and the positive moment bearing capacity of the composite beam are shown in Table 1.

[0196] Table SEQ Table\* ARABIC 1

[0197]

[0198] Step S12: Combine the cross-section design results in step S1 to perform semi-rigid node design. The basic parameters of the semi-rigid node are shown in Table 2:

[0199] Table 2

[0200]

[0201] Step S13: Based on the cross-sectional design results from Step S1, a calculation model was established using the finite element software SAP2000. To improve the structural lateral stiffness and overall horizontal bearing capacity, six sets of chevron-shaped buckling-restrained braces were installed in the X-direction and four sets of chevron-shaped buckling-restrained braces were installed in the Y-direction on each floor. By adjusting the stiffness of the buckling-restrained braces, the lateral stiffness of the semi-rigid model with added braces in both principal axis directions was roughly equivalent to that of the original rigid-connected model.

[0202] Step S14: Define the node nonlinear properties according to the basic parameters of the node described in step S2, and define the nonlinear working conditions and combinations, as shown in Table 3.

[0203] Table 3

[0204]

[0205] in, D Indicates constant load condition, L Indicates live load conditions, W x express x Windward load condition, W y express y Windward load condition, E x express x To earthquake conditions, E y express y Towards earthquake conditions.

[0206] Step S15: Verification of the structural bearing capacity and normal use status:

[0207] The period and inter-story drift angle of the semi-rigid connection steel frame and the rigid connection steel frame are compared, the data used in the period calculation result is as shown in Table 4, and the data used in the inter-story drift angle calculation result is as shown in Table 5.

[0208] Table 4

[0209]

[0210] Table 5

[0211]

[0212] The results show that the overall stiffness of the structure is reduced more when the semi-rigid connection is used, and the period is increased by nearly 3 times compared with the rigid model. After using the semi-rigid connection, the lateral displacement of the structure increases more under the same horizontal load, which is nearly 4-6 times that of the rigid node. After setting the buckling restrained brace (BRB), the lateral displacement of the structure is greatly reduced.

[0213] The deflection of the typical frame beam of different floors under the vertical load working condition (P-Δ) D + L ) is compared, and the results are shown in Table 6.

[0214] Table 6

[0215]

[0216] The results show that the vertical deflection of the semi-rigid connection steel frame beam is larger than that of the rigid connection steel frame, which is about 1.6-2.7 times that of the original rigid connection steel frame beam.

[0217] In addition, economic analysis is carried out, as shown in Table 7, and the results show that the semi-rigid connection steel frame can save more than 20% of the steel quantity compared with the traditional rigid connection steel frame under the same mechanical performance (i.e. with support). The system achieves the effect of reducing the steel quantity and improving the economic benefit.

[0218] Table 7

[0219]

[0220] The design method of the present application is scientific, accurate and effective, and can fully play the advantages of the semi-rigid connection steel frame-support structure, such as high bearing efficiency, high section utilization rate and good economic benefit.

[0221] The direct design method of the present application is a semi-rigid nonlinear design idea, which saves a lot of iteration and repeated trial calculation process compared with the existing repeated iteration and trial and error design method, and quickly gives a design scheme with simple steps.

[0222] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements shall be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A direct design method for a semi-rigid connected steel frame-support structure, characterized in that: The method comprises the following steps: Step S1: Determine the cross-sectional dimensions of the frame beams, frame columns, and plate components based on the design load of the semi-rigid connection steel frame-support structure, and calculate the design value of the internal force; Step S2: Select the bolt type and optimize the structure of the beam-column joint area to determine the bending bearing capacity of the beam-column joint and the stiffness of each component; Step S3: Establish an overall model of the semi-rigid connection steel frame-support structure. According to the building functional layout and structural stiffness requirements, adjust the stiffness of the buckling restraint support so that the error between the lateral stiffness of the semi-rigid model with added supports in the two main axis directions and the original rigid connection model is less than a set threshold. Step S4: define the node nonlinear properties, nonlinear working conditions and combinations, and perform ultimate limit state and serviceability limit state verification of the semi-rigid connection steel frame-support structure; The step S2 includes: Step S201: preset the end plate width to be equal to the steel beam flange width, preset the type of bolt node, and verify the tensile bearing capacity of the weakened section of the end plate; Step S202, selecting the one-way bolt type and determining the number of one-way bolts; Step S203, designing the one-way bolt arrangement; Step S204, calculating the tensile bearing capacity of the one-way bolts of each row of bolts, the bending bearing capacity of the end plate, and the tensile bearing capacity of the steel pipe column wall; Step S205, calculating the design value of the tensile bearing capacity of the i-th row of bolts, the design value of the tensile bearing capacity of the upper and lower rows of steel bars on the floor slab, the local compressive bearing capacity of the concrete in the steel pipe column, and the compressive yield bearing capacity of the steel pipe column wall web; Step S206, solving and calculating the height of the compression zone, determining the number of bolt rows in the tension zone, and calculating the design value of the node negative moment bending bearing capacity; Step S207: Verify whether the sum of the design value of the node's negative bending moment flexural bearing capacity and the design value of the composite beam's positive bending moment flexural bearing capacity is greater than the composite beam's bending moment design value; if not, return to step S202, increase the number of one-way bolts, and redesign the node structure; if still not, increase the H-beam cross-section height and redesign the node structure; In step S205, the calculation i Design value of tensile bearing capacity of bolt row F bo,i , Design value of tensile bearing capacity of upper and lower rows of steel bars on floor slabs F tr and F br , Local compressive bearing capacity of concrete in steel tube columns F cc , Compressive yield bearing capacity of steel pipe column wall web F cs The specific method is: in, A tr and A br are the total cross-sectional areas of the upper and lower rows of steel bars within the effective width of the floor slab section in the negative bending moment area, f ru is the design value of the tensile strength of the steel bar, b cc is the width of the concrete inside the column, f cu is the compressive strength of concrete cube, x ch is the height of the compression zone, t w is the thickness of the web of the rectangular steel tube column; F b is the tensile bearing capacity of the one-way bolt; F ep is the end plate bending capacity; F tcf is the tensile bearing capacity of the steel pipe column wall; f y is the steel yield strength of the steel beam.

2. A direct design method for a semi-rigid connected steel frame-support structure according to claim 1, characterized in that: The design loads of the semi-rigid connection steel frame-support structure include dead load, wind load, earthquake load in two directions, wind load in two directions and a combination according to load specifications.

3. A direct design method for a semi-rigid connected steel frame-support structure according to claim 1, characterized in that: In the step S1, determining the cross-sectional dimensions of the frame beams, frame columns, and plate components includes: Step S101, calculate the axial pressure of the concrete-filled steel tube column caused by the floor load of each floor: in, N i For the i Design value of equivalent column axis pressure of floor load, N gk and N qk are the standard values ​​of column axial pressure for dead load and live load, respectively. q s is the equivalent surface load of the floor slab self-weight, q gk and q qk are the standard values ​​of uniformly distributed dead load and live load on the floor, l y and l x Calculate the spans for the slabs parallel and perpendicular to the design beam length directions separately; Step S102, calculate the design value of the axial pressure of the concrete-filled steel tube column: in, N in For the i Design value of axial pressure of concrete-filled steel tube columns on floors. N i For the i Design value of equivalent column axis pressure of floor load; Step S103: Design the cross-section of each layer of concrete-filled steel tube columns according to the following formula: in, f s is the design value of steel tensile strength, f c is the design value of concrete compressive strength, A s is the cross-sectional area of ​​the steel pipe, A c is the cross-sectional area of ​​concrete in the steel tube.

4. A direct design method for a semi-rigid connected steel frame-support structure according to claim 1, characterized in that: In step S1, calculating the design value of internal force includes the following steps: Step S104, reinforcing the floor slab; Step S105: Calculate the design value of the composite beam bending moment M ; Step S106, designing the cross section of the H-shaped steel beam; Step S107: Calculate the design value of the beam end shear force V : Step S108: Verify whether the shear bearing capacity of the composite beam meets the requirements. ,in, h w is the web height of the steel beam section ，t w is the web thickness of the steel beam section, f y is the steel yield strength of the steel beam; if it meets the requirements, the design meets the requirements. If this step verification cannot meet the requirements, return to step S106 and increase the thickness of the web of the H-shaped steel beam section. t w , redesign the H-beam section.

5. A direct design method for a semi-rigid connected steel frame-support structure according to claim 4, characterized in that: The calculation of the composite beam bending moment design value M Specifically: in, M gk is the standard value of the dead load bending moment, M qk is the standard value of the live load bending moment, q s is the equivalent surface load of the floor slab self-weight, q gk and q qk are the standard values ​​of uniformly distributed dead load and live load on the floor, l y and l x Calculate the spans for the slabs parallel and perpendicular to the design beam length directions separately; The specific design value of the calculated beam end shear force is: in, V gk is the standard value of the dead load shear force, V qk is the standard value of live load shear force.

6. A direct design method for a semi-rigid connected steel frame-support structure according to claim 4, characterized in that: In the step S2, the structure of the beam-column node area includes the position and number of bolts in the beam-column node area, and the thickness of the end plate.

7. A direct design method for a semi-rigid connected steel frame-support structure according to claim 4, characterized in that: The step S2 further includes: Step S208, calculating the design value of the local compressive bearing capacity of the floor slab concrete; Step S209, calculating the design value of the node positive bending moment bending bearing capacity; Step S210: Calculate the stiffness of each component of the node.

8. A direct design method for a semi-rigid connected steel frame-support structure according to claim 1, characterized in that: The parameters of the one-way bolt include diameter, strength, and specifications; In step S204, the tensile strength of the one-way bolts in each row of bolts is calculated. F b , end plate bending bearing capacity F ep and the tensile bearing capacity of the steel pipe column wall F tcf Specifically: in, n b The number of one-way bolts contained in each bolt row, N t b is the design value of the tensile bearing capacity of the one-way bolt, n、e w is the calculation parameter, m is the distance between the center line of the bolt hole and the edge of the web of the T-connector, l eff,1 is the effective length of the plastic hinge line of the T-connector flange under the first failure mode, E e is the virtual work of the external force on the steel pipe column wall under the tensile load, δ Assuming unit displacement, t f is the thickness of the flange of the T-connector; The above-mentioned bearing capacity shall also meet the following requirements: If not, return to step S203 and increase the distance between the center line of the one-way bolt hole and the edge of the web of the T-shaped connector. m , redesign the one-way bolt arrangement; if it still cannot meet the requirements, return to step S201 and increase the end plate width b ep , reduce the thickness of the end plate t ep , redesign the end plate size.

9. A direct design method for a semi-rigid connected steel frame-support structure according to claim 7, characterized in that: In step S206, the height of the pressure zone is calculated. x ch , so the calculation process for determining the number of bolt rows in the tension zone is: Calculate the design value of the negative moment bending capacity of the node M hu : in, F bo,it is the design value of the tensile bearing capacity of the tension bolt row, h i is the distance between each row of bolts in the tension zone and the upper flange of the steel beam, is the thickness of the floor slab, h tr is the distance between the upper row of steel bars and the upper edge of the floor slab, h br is the distance between the lower row of steel bars and the lower edge of the floor slab, h b is the cross-sectional height of the H-beam; In step S208, the design value of the local compressive bearing capacity of the floor slab concrete is calculated: in, b cf is the width of the column wall flange, x con is the height of the compression zone of the floor slab, β is the local compressive strength increase coefficient of concrete, f cu is the design value of concrete cube compressive strength; In step S209, calculating the design value of the node positive bending moment bending capacity includes: Assuming that the neutral axis is displaced within the floor slab, the height of the compression zone of the slab is calculated according to the equation x con : When satisfied When the neutral axis is inside the floor slab, the design value of the node's positive bending moment bearing capacity is M su Calculate as follows: If not satisfied , then let x con = h con Substitution F con , calculate the height of the compression zone according to the equation x ch : At this time, the design value of the node's positive bending moment bending bearing capacity M su Calculate as follows: in, F bo,it is the design value of the tensile bearing capacity of the tension bolt row, h i is the distance between each row of bolts in the tension zone and the upper flange of the steel beam, is the thickness of the floor slab, x ch is the height of the compression zone, F bo,i For the i Design value of tensile bearing capacity of bolt row, F cc is the local compressive bearing capacity of concrete in steel tube column, F cs is the compressive yield bearing capacity of the steel pipe column wall web, is the design value of the local compressive bearing capacity of the floor slab concrete.

10. A direct design method for a semi-rigid connected steel frame-support structure according to claim 1, characterized in that: The nonlinear properties of the node include the node bearing capacity and initial stiffness, and the nonlinear working conditions and their combinations include dead load conditions, live load conditions, x Windward load condition, y Windward load condition, x To earthquake conditions, y directional earthquake conditions, and combinations of these conditions.

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