![\"fig-1\"](\"http:\/\/141.23.68.248\/wp\/wp-content\/uploads\/2023\/02\/Fig.1.png\")
<\/a><\/p>\n<\/p>\n
The boundary conditions of the completed bridge are shown in the table. x represents the
\nlongitudinal bridge direction, y represents the horizontal bridge direction, and z represents the
\nvertical direction. 0 means free, 1 means fixed.<\/p>\n
<\/p>\n
The proportion distribution of loads borne by arches and beams directly determines whether the <\/p>\n <\/p>\n When the boom force is 33% of the dead load, the stress of the main girder is too large, the truss <\/p>\n <\/p>\n The rise-span ratio is one of the important parameters of an arch bridge, which has a great influence Select 5 different engineering rise-span ratios such as 1\/5, 1\/4.5, 1\/4, 1\/3.5, 1\/3 for calculation and <\/p>\n When the rise-span ratio of the main arch rib is small, the stability coefficient of the structure <\/p>\n The arch at the top of the arc of the dome can distribute the pressure to both sides, and the <\/p>\n In the stability calculation of CFST double-layer stacked arch bridge, the most critical part is the Double-layer stacked arch, double-layer steel arch bridge is narrower and taller than ordinary <\/p>\n Here You can Find the Parametric Model:\u00a0Dynamo File<\/a><\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" 1.Background: The double-layer stacked arch is a new type of structure developed in recent years. Compared with the conventional tie-rod arch, the shape is more graceful and dynamic. The curved arch bridge in this designContinue reading<\/a><\/p>\n","protected":false},"author":182,"featured_media":0,"parent":11929,"menu_order":2,"comment_status":"closed","ping_status":"open","template":"","meta":{"footnotes":""},"class_list":["post-12622","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/pages\/12622","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/users\/182"}],"replies":[{"embeddable":true,"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=12622"}],"version-history":[{"count":2,"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/pages\/12622\/revisions"}],"predecessor-version":[{"id":12641,"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/pages\/12622\/revisions\/12641"}],"up":[{"embeddable":true,"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=\/wp\/v2\/pages\/11929"}],"wp:attachment":[{"href":"http:\/\/141.23.68.248\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=12622"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}<\/a><\/p>\n
\nstress on the arch bridge structure is reasonable. The dead load is transmitted to the main arch
\nthrough the suspender, and the force of the suspender is the most intuitive expression of the
\nproportion of the main arch bearing the dead load. Comparing and analyzing the cases where the
\nsuspender force of the completed bridge bears 33%, 60%, 80% and 100% of the dead load weight, the
\nforce situation of the main components of the bridge is obtained, and the results are shown in the
\ntable.<\/p>\n<\/a><\/p>\n
\nsection needs to be increased, the amount of steel is increased, and the dead load is also increased.
\nThe proportion of the structure bearing its own dead load will also increase, and the economy is poor.
\nIt shows that the dead load distribution ratio of the arch beam is unreasonable. When the boom force
\nis 60%, 80%, 100%, the force of the main girder and the main arch is small, which meets the
\nrequirements of the code and has a certain margin. From the point of view of stress, the three
\ndistribution ratios are all feasible, but from the point of view of the overall stability of the arch bridge
\n(especially the upper arch) and buckling stability, the main arch is a compression member, and the
\nstress should not be too large, and the main beam is a bending member. , can give full play to the
\nadvantage of the high stiffness of the main beam, and the stress of the main arch should be reduced
\nas much as possible. Comparing the stress level of the arch under the second, third and fourth
\nworking conditions, the stress level of the arch under the second working condition is the lowest and
\nthe stability is the best. Therefore, it is finally determined that the boom force bears about 60% of the
\ndead load weight.<\/p>\n3. Slope-span ratio:<\/h3>\n
\non the overall force and deformation of the structure. A smaller rise-span ratio makes the axial shape
\nof the arch closer to that of a flat arch, and the axial force in the arch ribs and tie beams increases,
\nwhile the vertical stiffness of the structure decreases.
\nIn the design of this system, the arch axes of the main and auxiliary arch ribs are all quadratic
\nparabolas. The main arch rib has a relatively high section stiffness and is the main arch structure. The
\nmain and auxiliary arch ribs are connected by tie rods to form a stable system of space.<\/p>\n
\nanalysis, (during the calculation, keep the span constant, and obtain different Sagittal Ratio).<\/p>\n<\/a><\/p>\n
\nincreases with the increase of the rise-span ratio. When the rise-span ratio increases to a certain
\nvalue, the stability coefficient reaches the maximum and the structure is most stable. The rise-span
\nratio continued to increase, and the stability coefficient showed a downward trend. This is because
\nthe decrease in rise-span ratio increases the axial pressure of the arch rib, and the axial pressure is
\ninversely proportional to the geometric stiffness of the member, resulting in a decrease in the overall
\ntangential stiffness of the arch rib and a decrease in the stability of the structure. When the rise-span
\nratio is greater than the ideal stable rise-span ratio value, the component force of the stay cables in
\nthe main arch rib surface increases continuously with the increase of the rise-span ratio, so that the
\naxial pressure of the arch rib does not decrease but increases. leading to a downward trend in the
\nstability of the structure. Calculations show that under the condition that other conditions remain
\nunchanged, there is an ideal rise-span ratio that makes the concrete-filled steel tube double-layer
\nstacked arch bridge the most stable, so the rise-span ratio of the main arch rib should be as close to
\nthis value as possible during design.
\nIn general, the increase of rise-span ratio will significantly reduce the axial force of arch rib and tie
\nbeam, the deflection of tie beam, the force of boom, and the bending moment, but it is relatively
\ninsensitive. As the rise-span ratio increases, its influence on the structural force gradually weakens, so
\nthe higher the rise-span ratio, the better. At the same time, an excessively large rise-span ratio will
\nincrease the amount of materials and affect the aesthetics of the structure. The choice of rise-span
\nratio also needs to take into account the requirements of structural force and economical beauty. On
\nthe whole, the rise-span ratio of double-stacked arch bridges is more appropriate to be around 0.28,
\nbut not less than 0.25.<\/p>\n4.The thickness of the arch ring:<\/h3>\n
\nload-bearing capacity is better. Enhance the sense of depth of the space, but also enrich the visual
\nexperience. And beautiful and interesting, adding a romantic and elegant atmosphere to the space.
\nThe arch ring can be made into two forms of equal thickness and unequal thickness. In real life, equal
\nthickness is generally used. This form of equal thickness will also be used in this design, and it is a
\nlong-span arch bridge. The value is based on the bridge span, loss The height, building materials and
\nload size shall be determined through trial calculation.
\nFor reinforced concrete slab arch thickness:
\nArch thickness: h =(1\/200~1\/250)L<\/p>\n<\/p>\n5. Rigidity of the main arch rib:<\/h3>\n
\nselection of CFST arch rib stiffness. The calculation methods of arch rib stiffness mainly include:
\nconversion section method, superimposed element method and unified theory method. The
\nconverted section method is based on the principle of equivalent stiffness. The area of CFST is
\nconverted into the area of steel tubes according to the equivalent principle of compressive stiffness,
\nand then the stiffness of CFST components is calculated by the basic method. The superimposed
\nelement method is to divide the concrete section of the steel pipe into two parts, concrete and steel
\npipe, and consider the coordination of the longitudinal strain of the steel pipe and concrete to obtain
\nthe stiffness of the member. The basic idea of the unified theory method is to convert the steel pipe
\nconcrete into a material, select the correct constitutive relations of steel and core concrete under
\ncomplex stress conditions, and use the equilibrium conditions and deformation coordination
\nconditions to synthesize the two constitutive relations The combination relationship of components
\nincludes the tightening effect in the combination relationship, and then establishes the internal and
\nexternal force imbalance conditions and deformation coordination conditions, and finds the
\nrelationship between internal force, (or stress) and strain.
\nAs we all know, in the construction process of composite arch bridge, the main arch, main girder, sling
\nand auxiliary arch rib support, cast-in-place bridge deck, and pavement of construction bridge deck
\nmust have the problem of stress superposition. Therefore, it is unreasonable and unrealistic to
\ncalculate the various components of the cross-section formed by stages as the overall cross-section
\nformed at one time. Therefore, the stress calculation of the double-layer stacked arch bridge should
\nconsider the stage-by-stage formation process of the section, and calculate according to the stress
\nsuperposition method.<\/p>\n6. Summary:<\/h3>\n
\nsingle-layer steel arch bridges due to the configuration of double-layer decks, so its structure and
\nmechanical behavior are different. The bridge is complicated, so it depends on the actual situation
\nand is determined after trial calculation.<\/p>\n