Study And Application On The Assembled Monolithic Space Grid Box Structure In H Type Steel

With the decreases of cultivated lands and the shortage of urban lands,the demands for large-span and multi-storey buildings with small constructional depths are dramatically increasing.The selected constructional depth of a floor may significantly affect the overall height of the building.It is a trend for building structures to reduce the floor height by adopting new floor structures.The depth of beams increases with the increase of the span,which makes the beam deeper and heavier than expected for traditional floor structures.The long-span space steel grid structure is alternative in order to solve such problems.This type of structures provides appealing benefits in terms of construction costs such as large spanning capabilities with minimal materials,small floor heights,fast constructions,and the advantages offered by ordinary composite beam constructions.The long-span space steel grid structure is suitable for multi-s torey,high-rise and long-span industrial and public buildings.It h as been applied in many projects.It is composed of orthogonal and or thogonal-diagonal lattice hollow grid plates which consist of steel hollow beams.The top and bottom ribs of the steel grid are made of p rofiled steel,and the middle is connected by square steel tube.The reinforced concrete floor slabs are poured on site.The shear key c onnect the top and bottom ribs of the structure,which makes the who le structure work together.The height and width of the shear key is exactly the same.The mechanical model of the structure is a spatia l plate,which has three-dimensional mechanical behaviors.As the st eel grid is open,the structure has the characteristics of light wei ght,large stiffness and good human comfortness.Various pipelines a re able to pass through the hollows of the steel grids which saves b uilding space and reduces the cost of the project.Based on the method of combining the experimental research and t heoretical analysis,the static analysis,modal and comfort analysis and blast wave analysis were conducted for the assembled monolithic space grid box structure in H type steel.Combined with the actual project,the test of a steel grid wall frame was carried out.In th e pure shear state,the test of the two groups of shear key specimen s was done.The main research of the thesis includes:(1)By means of continuum analysis method and equivalent stiffne ss method,the solution of simply supported open web sandwich plate around rectangular plane is obtained.The internal force calculation formulas of surface concrete slab,upper rib H-beam and lower rib H-beam are derived.The program calculation is carried out by using M ATLAB.The comparison with the results of finite element analysis sh ows that the continuum derivation has a higher precision.(2)A simulation model hysteretic test was carried out on a frame wall in a practical project.The wall frame structure shows good overall performance and good safety reserve.The load-displacement hysteresis curves of the specimens are quite full,which indicates that the structure has good energy dissipation and deformation capacity,and good ductility.(3)Vibration response of orthogonal positively placed H-shaped steel space floor under human-induced load is studied.The results s how that the floor has excellent anti-vibration performance and comf ort meets the requirements of national standards.Because the basic natural frequencies of floor are low,the influence of active loads such as partition walls on the natural frequencies of structures sho uld be considered.Reasonable structural layout can make full use of the spatial stress characteristics of the structure and enhance the anti-vibration ability of the structure.When the ratio of the plan e length to the short side is 1.5,orthogonal open-web grid is suita ble;when the ratio of the plane length to the short side is more th an 1.5,orthogonal oblique open-web grid is suitable.(4)The anti-explosion design of H-beam space steel grid roof with orthogonal oblique placement was carried out.The vibration response of the roof was studied under the action of explosive shock wave,and the economic analysis was carried out.The results show that the vertical peak displacement response point of the orthogonal oblique H-beam space steel grid roof appears near the center of the low-order mode shape,and the roof structure has good explosion resistance,and the economic index is better than that of the traditional structure.(5)Simulating the loading conditions of specimens under pure shear state,two groups of shear bond specimens with and without vertical stiffeners were tested.The results show that under pure shear state,the bearing capacity of components is greatly improved by vertical stiffeners,and shear deformation is the main factor of shear bonds.Vertical stiffening plate can significantly improve the stiffness and load-bearing range of shear bond joints,and the specimens have good ductility.Because of the vertical stiffening plate,the upper and lower ribs of the shear keys work together with the square steel tube as a whole,and the shear keys have more uniform force in the joint area,which can give full play to the performance of the material.(6)Combined with a practical project,the general design principles and construction measures of key joints of assembled integral H-shaped steel floor are introduced,and the static characteristics of the floor are analyzed.