CN-116479741-B - Beam body structure of UHPC (ultra Violet) filling part of shearing and bending section and prefabricating method thereof

CN116479741BCN 116479741 BCN116479741 BCN 116479741BCN-116479741-B

Abstract

The invention provides a beam body structure of a shear bending section filling part UHPC and a prefabricating method thereof, which solve the problems that when the existing beam body is poured by using UHPC, the existing beam body not only brings larger dead weight of the structure and higher self-cost, but also causes the increase of the whole construction cost of a bridge and prolongs the construction period. The invention comprises a common concrete section beam body and a UHPC section beam body, wherein the UHPC section beam body and the common concrete section beam body are arranged at intervals along the length direction of the beam body. The invention combines the stress characteristics of the shearing and bending section of the reinforced concrete beam, only fills UHPC material with a certain length at the key part of the reinforced concrete shearing and bending section to improve the mechanical property of the shearing and bending section of the main beam, can greatly improve the shearing and bearing capacity of the main beam, and simultaneously fills UHPC at the partial section of the shearing and bending section of the main beam, thereby effectively reducing the cross-sectional area of the beam near a fulcrum, lightening the dead weight of the structure, reducing the construction cost of the UHPC and having better economy and practicability.

Inventors

LI CHUNLIANG
DAWAZHAXI
LI MANGYUAN
LIU XIANG
SHEN YANBING
XU PING

Assignees

吉林建筑大学
中建七局第一建筑有限公司

Dates

Publication Date: 20260505
Application Date: 20221209

Claims (6)

1. The beam body structure of the UHPC filling part of the shear bending section is characterized by comprising a common concrete section beam body and a UHPC section beam body, wherein the UHPC section beam body and the common concrete section beam body are arranged at intervals along the length direction of the beam body; The UHPC section beam body comprises a plurality of UHPC beam body pouring layers (2) in the up-down direction, the common concrete section beam body comprises a plurality of common concrete beam body pouring layers (1) in the up-down direction, the UHPC beam body pouring layers (2) are correspondingly connected with the common concrete beam body pouring layers (1) one by one, and the thicknesses of the UHPC beam body pouring layers (2) and the common concrete beam body pouring layers (1) on the same layer are the same; The UHPC beam body pouring layer (2) and the common concrete beam body pouring layer (1) of the same layer are of an integral pouring molding structure; The UHPC beam body pouring layer (2) and the common concrete beam body pouring layer (1) which are adjacent up and down are of layered pouring structures; S1, establishing a shear bearing capacity model of the UHPC beam with a shearing and bending section partially filled according to the material characteristics of UHPC materials and common concrete; s2, according to the shear bending section local filling UHPC beam shear bearing capacity model, establishing a shear bending section filling UHPC simple beam shear bearing capacity formula: in order to simplify the calculation formula of the shearing bearing capacity of the UHPC back beam with the shearing bending section partially filled, the following steps are provided: The formula reduces to: Wherein beta is the length ratio coefficient of UHPC crack; b is the beam width; c is the horizontal projection length from the intersection point of the longitudinal steel bar and the bottom end of the inclined crack to the distance from the top end of the inclined crack; f cu,k is a standard value of the compressive strength of the concrete cube; A s is the area of the longitudinal ribs; f s is the strength of the longitudinal ribs; p sv is the rate of the hoop; f sv is the strength of the stirrup; Alpha is 0.6; w is the random distribution coefficient of the steel fibers; sigma f is the pullout strength of the steel fiber; v f is the volume doping amount of the steel fiber; l f is the length of the steel fiber; d f is the diameter of the steel fiber; Tau f is the average bonding stress of the fiber and the matrix, and has uniaxial compressive strength with UHPC ; S3, according to the relevant calculation parameters of the shear bearing capacity of the main beam and the load required to be borne by the shear bending section beam body, adopting a shear bending section filling UHPC beam shear bearing capacity formula to calculate the lengths and positions of the UHPC section beam body and the common concrete beam body; S4, installing a girder template; S5, installing a reinforcement cage in the girder template; s6, according to the lengths and positions of the UHPC section beam body and the common concrete beam body, layering and pouring UHPC and common concrete at corresponding positions in the main beam template to form a UHPC beam body pouring layer (2) and a common concrete beam body pouring layer (1) which are mutually connected; S7, pouring is completed, and after the girder is solidified and formed, the girder template is removed, so that the prefabrication construction of the girder is completed; The joint of the UHPC beam body pouring layer (2) and the common concrete beam body pouring layer (1) is of a left-right staggered cross invasion structure in the up-down direction.
2. A beam structure of a shear bend filling portion UHPC as claimed in claim 1, wherein the thickness of the layer of each layer has an intrusion length of 2/3 of the intersection intrusion structure of the left and right sides.
3. The prefabrication method of the beam body structure of the UHPC with the shear bend section filling part, as set forth in claim 1, is characterized in that when the layered casting of the UHPC and the common concrete in the step S6 is carried out, the UHPC beam body casting layer (2) and the common concrete beam body casting layer (1) of each layer are cast at the same time and with equal thickness; the joint of the UHPC beam body pouring layer (2) and the common concrete beam body pouring layer (1) is subjected to pouring treatment in a cross invasion manner, so that a left-right staggered cross invasion structure is formed; the thickness of the layer of the differential crossintrusion structure is 2/3 of the intrusion length of each layer.
4. The method for prefabricating the beam body structure of the shear bend section filling part UHPC according to claim 3, wherein the balance equation of the oblique crack section of the shear bend section partial filling UHPC beam shear bearing capacity model in the step S1 is as follows: ΣX=0→D=Ts+V W2 →σbz=A s f s +V w sinθ ΣY=0→V=Tsv+F+Vw1→V=p sv f sv bc+τbz+V w cosθ wherein sigma is the compressive stress born by the concrete in the shear compression area; τ is the shear stress borne by the UHPC in the shear nip; b is the beam width; f is the vertical shearing force on the concrete shearing surface; D is horizontal pressure shearing force on the concrete shearing surface; T s is longitudinal rib tension; A s is the area of the longitudinal ribs; f s is the strength of the longitudinal ribs; T sv is the tension of the stirrup; p sv is the rate of the hoop; f sv is the strength of the stirrup; d is the length of a moment arm of V w from the point O, and z is the height of the shear-pressure surface concrete; a is the distance from the shearing and pressing surface to the support; c is the horizontal projection length from the intersection point of the longitudinal steel bar and the bottom end of the inclined crack to the distance from the top end of the inclined crack; V w is steel fiber drawing force; v w1 is the vertical component of the steel fibre drawing force; V w2 is the horizontal component of the steel fiber drawing force; h 0 is the effective height of the beam section; θ is the angle between the main oblique crack and the beam axis.
5. The method for prefabricating the beam body structure of the UHPC filling part of the shearing bending section according to claim 3, wherein the calculation mode of the ratio coefficient beta of the length of the UHPC crack is as follows, the filling length of the UHPC of the shearing bending section is l, the position of the lower end of the inclined crack is p, the length from the starting point of the UHPC filling of the shearing bending section to the position of the lower end of the inclined crack is l p , the projection length of the inclined crack on the horizontal plane is c, When the filling length l < l p of the shearing bending section UHPC is smaller than the horizontal projection length of the oblique crack passing through the UHPC section beam body, the horizontal projection length of the oblique crack passing through the UHPC is 0, and beta=0; When the shear bend UHPC fills the length l p <l<(l p +c), the oblique slit passes through both materials simultaneously, ; When the shear bend section UHPC fills length l > (l p +c), the oblique fracture portion passes through UHPC, where β=1.
6. The method for prefabricating a beam structure of a shear bend filling portion UHPC according to claim 5, wherein the projection length of the oblique slit on the horizontal plane is c, ; Wherein lambda is the shear span ratio of the positive section at the top end of the inclined section; h 0 is the effective height of the beam section; k is an influence coefficient.

Description

Beam body structure of UHPC (ultra Violet) filling part of shearing and bending section and prefabricating method thereof Technical Field The invention relates to the technical field of building construction, in particular to a beam body structure of a shear bending section filling part UHPC and a prefabrication method thereof. Background The Ultra-high performance concrete (Ultra-High Performance Concrete) has low structure mass and porosity, excellent corrosion resistance and fatigue resistance, and higher tensile strength and compressive strength, and if the Ultra-high performance concrete is used for bridge structures, the shearing resistance and the bending resistance of the girder can be effectively improved. The existing case of adopting UHPC in bridge construction is more and more, but research discovers that the UHPC structure has great self weight, the product material and the construction cost are higher, if the main girder of the whole bridge is poured by UHPC, the larger self weight of the structure and the higher cost of the main girder can be brought, and in addition, the bridge support needs to be added for balancing the stress, the whole construction cost of the bridge can be increased, and the construction period is prolonged. Disclosure of Invention In order to solve the problems that the prior beam body in the background technology is poured by UHPC, not only can bring about larger dead weight of the structure and higher cost of the beam body, but also can cause the increase of the whole construction cost of the bridge and the extension of the construction period, the invention provides a beam body structure of UHPC of a filling part of a shearing bending section and a prefabrication method thereof. The technical scheme of the invention is that the beam body structure of the UHPC of the shear bending section filling part comprises a common concrete section beam body and a UHPC section beam body, wherein the UHPC section beam body and the common concrete section beam body are arranged at intervals along the length direction of the beam body. Preferably, the UHPC section beam body comprises a plurality of UHPC beam body pouring layers in the up-down direction, the common concrete section beam body comprises a plurality of common concrete beam body pouring layers in the up-down direction, the UHPC beam body pouring layers are in one-to-one correspondence connection with the common concrete beam body pouring layers, and the thickness of the UHPC beam body pouring layers on the same layer is the same as that of the common concrete beam body pouring layers. Preferably, the joint of the UHPC beam body pouring layer and the common concrete beam body pouring layer is of a left-right staggered cross invasion structure in the up-down direction. Preferably, the intrusion length of the left-right staggered cross-intrusion structure of each layer is 2/3 of the layer thickness value. Preferably, the UHPC beam body pouring layer and the common concrete beam body pouring layer on the same layer are of an integrated pouring molding structure; the UHPC beam body pouring layer and the common concrete beam body pouring layer which are adjacent up and down are layered pouring structures. A prefabrication method of a beam body structure of a UHPC (ultra Violet) filled part of a shearing and bending section comprises the following steps of S1-establishing a shearing and bending section partial filling UHPC beam shearing bearing capacity model according to the material characteristics of UHPC materials and common concrete; s2, according to the shear bending section local filling UHPC beam shear bearing capacity model, establishing a shear bending section filling UHPC simple beam shear bearing capacity formula: Wherein beta is the length ratio coefficient of UHPC crack; b is the beam width; c is the horizontal projection length from the intersection point of the longitudinal steel bar and the bottom end of the inclined crack to the distance from the top end of the inclined crack; f cu,k is a standard value of the compressive strength of the concrete cube; A s is the area of the longitudinal ribs; f s is the strength of the longitudinal ribs; ρ sv is the collar ratio; f sv is the strength of the stirrup; Alpha is 0.6; omega is the random distribution coefficient of steel fibers; sigma f is the pullout strength of the steel fiber; v f is the volume doping amount of the steel fiber; l f is the length of the steel fiber; d f is the diameter of the steel fiber; Tau f is the average bonding stress of the fiber and the matrix, and has uniaxial compressive strength with UHPC Coefficient A, B takes on the value S3, according to the relevant calculation parameters of the shearing bearing capacity of the main beam and the load required to be borne by the shearing and bending section beam body, adopting a shearing and bending section filling UHPC beam shearing bearing capacity formula to calculate the lengths and positions o