Analysis Of Several Factors Of The Multi-storey Underground Garage’s Structure Cost Optimization

With the accelerating of urban construction, the number of new residentialbuildings is increasing but the area of urban construction land is decreasing. At thesame time the value of car ownership per capita is growing as people’s living level isincreasing, results in the increasing number of parking spaces around the village andthe difficult to satisfy the demand. In order to solve the problem of insufficientparking spaces as much as possible, most developers will develop the undergroundspace into multi-storey underground garage, which can solve such king of problemand at the same time the roof of the underground garage can also be green in order toimprove the per capita public green area. However, adopting this approach will needmore materials to construct such multi-storey underground garage, results in theincreasing cost of materials. In order to reduce the cost of materials developers withhelp of designer will take the effect on multi-storey underground garage as well asreasonable optimization approach to reduce the material cost for multi-storeyunderground garage.First, this paper introduces the optimization design for roof and middle floor planand put forward three approaches for the roof plan of the underground garage: mainbeams arrangement without secondary beams, cross secondary beams andgrillage-shaped beams, as well as three approaches for the middle floor plan of theunderground garage: main beams without secondary beams, one secondary beam andcross beams. This paper discusses cost of these three kinds of approaches in the caseof other conditions unchanged. Second, this paper conducts optimization analysis ofthe ductility of frame column; discuss the relationship between the ductility of framecolumn and the cost of materials as well as the impact of the frame section size andthe strength of concrete on the ductility of frame column; optimize the size of thecolumn grid. Specific optimization analysis methods include impact of parking andmaterial cost on the size of column grid. At last, this paper discusses the value of firelane load reduction factor through the optimization analysis of the fire lane loadparameter.It can be concluded from a series of analysis that as for the multi-storyunderground garage, the approach of cross beams is economy for roof while the onebeam approach is economy for middle floor. It is a reasonable way to effectively reduce the cost of materials that make clear the live load on each floor of themulti-story underground garage and appropriately arrange secondary beams. In orderto reduce the axial compression ratio of frame column, the general way is to increasethe size of the frame column section. However, it is harmful for the structure becausethe increasing of the frame column section size is easy to cause the frame columnshear span ration is much large to form short column. In order to increasing thesection size of frame column, raising the strength of concrete of frame column is alsoa way to reduce the axial compression ratio of frame column. Though increasing thestrength of concrete will lead to the increase of price of concrete, the usage of highstrength concrete will reduce the dosage of concrete and the overall cost and at thesame time, reduce the frame column section size and improve the use of theunderground garage. Small column grid (5300mm*5400mm) can be used as a kindof more economic column grid which can substitute the large column grid (8100mm*8100mm). Fire lanes of live load will increase with the decrease of the reductionfactor and increase of the thickness of soil. Considering the fire lane live loadreduction will cause the value of live load is less than the standard value while it isobvious that the reduce of the live load value will reduce the cost of materials. Thus,the actual multi-storey underground garage engineering should consider the fire laneroof live load values in accordance with the reduction factor.