Mechanism Study And Application Of Load Bearing Scafford Under Cast-in-situ Box Girder

Cuplok Scaffolding is widely used in municipal bridge projects, because of itsadvantages. Due to the lack of theoretical basis in the design and construction process,the less relevant construction experience, the abundant poles and the overall complexmechanics regularity, any carelessness will result in the collapse of the formwork,causing casualties and property losses.At present, the existing Cuplok Scaffolding Safety Specifications are aimed atthe design of bracket below the box girder, without proposing design standards forrod bracket under the flanges. This part is usually erected empirically; as a result,there is no quantitative basis, either from the angle of safety or economy. In addition,the studies at home and abroad are mainly directed at the mechanical performance ofbracket below the box girder in the pre-press stage. However, if we make a generalsurvey of the scaffold accident, it is clear that most of them occurred in the concretepouring process. Therefore, it is of great significance to study the mechanicalproperties of cup lock steel bracket during the concrete pouring process.This thesis takes the Girder Formwork bracket in West Third Ring-NavigationRoad project as the test object. By monitoring the internal forces during the processof concrete building, it studies the laws of internal force distribution andtransformation. Through the comparison between the theoretical analysis data and themeasured values, this thesis tries to explore the development processes of the internalforces of formwork support rod, inclined strut, and diagonal bridging, and to putforward the technical requirements for setting up the false work. The main points areas follows:(1) During the process of concrete pouring, the dangerous sections are those thatare newly poured. The concrete pouring has great influence on the parts within thescope of10m before and after the construction sections. Beyond this range, the framebody is less affected.(2) For the same standing tube, the upper internal force is stronger than that ofthe lower part. It is recommended that the upper pole interval should be reduced inpractical project. （3）For the stand bar at the bottom of the flange, the smaller the distance to thecentral axis is, the larger the internal force amplitude becomes. It is suggested that thelateral spacing of the stand bar near the central axis should be reduced in the project.(4) The component number of the tension and compression variable number inthe bracket increases when the concrete pouring speed is too fast. It is thus necessaryto control the speed of concrete pouring and to formulate measures to ensure uniformsymmetrical casting.(5) The cross strut below the flange is in great tension, and the tension in thelower part is greater than that in the upper part; As for the cross strut below the boxgirder, the lower part is mainly in tension, and the upper part is mainly incompression.(6) The maximum internal force of Cross strut is16kN. This exceeds thetheoretical sliding strength of the double fastener. So the extension bar of Cross strutshould use no less than three specially selected high-quality fasteners.(7) The angle between the slant tube below the flange and the template shouldbe less than90°, and the connector fasteners between the full framing poles shouldbe no less than three.