| The spatial steel grid box-like structure which applicated in the field of multilayer buildings is a new energy-saving and enviromental portentional structure.It is composed of grid floors,a type horizental bearing system,and grid wall,a type vertical bearing system.In chapter 2,at first,a honey-comb-like open-web plate was analysized with two methods: plate analogy method and finite element method.The comparing with finite element shows plate analogy method's advantages and disadvantages.In order to get a way out of the plate analogy method's difficulty in solving delflections and internal force,An cross beam method which ofen used in the feild of steel truss roof was used to calculate steel open-web plates.An orthogonal steel grid plate was decomposed to a series of open-web beams with large rectangular holes.The analytic solutions of the mid-span rib were deducted with crossing beam method.Viewing the mid-span hollow rib as a design object,a simplified design is proposed and the comparison with finite element method shows a good agreement.At the last of the chaper 2,the whole steps for the top chords and bottom chords is summarized.The open-web beams are basic bearing units.In chapter 3,all-shell-element numerical models for steel open-web girders are established and nonlinear parameters analysis are carried out to study the basic units,steel open-web beams with H-section ribs.The results of study shows that the marginal shearing-block always play a key role,which bearing bigger stress and bigger deformation and also shows control section's flange stress and web stress of the top and bottom chords have an obvious non-uniform distribution which could lead to unsafe situation.So two coefficents are obtained to correct the uneven distribution.At last,two formulas with correct coefficent are adviced and the formula's results shows a good agreement with finite element method.In the third chapter,four full-scale specimen of shearing block are made to compare the difference with stiffeners and without stiffeners.The test results provides a proof for the stiffener's good effect on the shearing pipe's bearing capacity.Stress concentration can be relieved obviously and enhance the rectangular pipe's ductility.The plate's frequencies are always the one of key parameters to open-web plate's comfort design.In the fouth chapter,375 numerical modals of steel-concrete open-web floors had been established with different parameters which including length-width ratio,span,plate-thickness and ribs' hollow rate,Based on the calculating database,a simplified formula for fundamental frequency is proposed by multi-parameter regression.Taking a five-dimension movie hall as an example,the formula result is broadly in line with the finite element method.In the fifth chapter,random vibration method was used to analysize the box-like structure as a aided design method.Random seismic response of the structure were calculated based on complex mode theory.And the displacement's reliability was obtained with a hypothesis of probability distribution of extreme value type I and the confidence interval with a specific probability was derived based on the mean value and variance of random seismic response peaks.Taking a exhibition hall as an example,the mean value and variance of random seismic response peak were calculated under KANAI-TAJIMI spectrum excitations.Meanwhile,14 complex-mode deterministic displacements were calculated under 14 seismic wave excitations.The results indicate that the two methods are consistent.The random response analysis method is an effective assistant calculation method for design of Spatial Steel-grid Box-structure,and based on that,the reliability of structures' responses can be estimated. |
PDF Full Text Request