| The appearance of prefabricated buildings in China can be traced back to the1950 s and 1960 s.At that time,the prefabricated buildings were mainly industrial buildings and large-slab systems.With the development of the economy and the continuous innovation of technology,With the aging of society,the shortage of labor in the construction market is increasing,and national leaders are paying more and more attention to the promotion,application and development of prefabricated buildings.When presiding over the study,General Secretary Xi pointed out: "We must do everything possible to increase the housing supply.At the same time,we must put the housing needs of the people in an important position and establish a sound housing standard system that is economical,applicable,environmentally friendly,resource-saving and safe." Speaking in the government work report: "Actively promote green buildings and building materials,vigorously develop steel structures and prefabricated buildings,and improve construction engineering standards and quality." On September 30,2016,the State Council Information Office held a policy meeting,detailing 9 The "Guiding Opinions on the Development of Prefabricated Buildings" issued on the 27 th of the following is hereinafter referred to as the Document No.71 of the State Council,which clearly states that China should strive to make the proportion of prefabricated buildings to 30% of new buildings in about 10 years.The country’s strength and determination to promote the development of prefabricated buildings.In order to respond positively to the country’s policy guidelines,the Shandong Provincial Department of Housing and Construction issued the "Shandong Province’s Prefabricated Building Development Plan"(2018-2025)in2018,which clearly stated the development goal: by 2020,Jinan and Qingdao’s prefabricated buildings will occupy new construction.More than 30% of buildings,other cities(counties)reached 25%,15%,by 2025,the proportion of the provinceshould reach more than 40%,and the text clearly stated that it is necessary to vigorously promote the assembly and construction of residential buildings,and promote steel.The development of structural housing.After many years of silence in China,the prefabricated residential buildings have ushered in another vigorous development.The assembly pilot and industrialization base projects have been implemented throughout the country.At the same time,the research work on fabricated residential building technology is also in progress.The implementation of the specifications and procedures of "Industrial Building Evaluation Standards","Assembled Concrete Building Technical Standards","Assembled Residential Building Design Standards","Assembled Concrete Structure Technical Regulations" also indicates that China is in full swing throughout the country.The prefabricated residential building technology is constantly improving and perfecting.These various favorable factors continue to promote the development of the domestic assembled residential building market,bringing the assembled residential building market into a new golden period of rapid development.As an important component of the prefabricated residential building system,prefabricated stair components play an indispensable role in the entire prefabricated residential building market and throughout the prefabricated building market,according to research in the current assembled residential building market.The use of prefabricated stair members has reached 100%.Whether it is a fully-assembled residential building or a partially-assembled residential building,a large number of prefabricated stair members are used,and the prefabricated stair members are also resistant to sliding shock and green energy.Energy-saving and ease of construction have been widely recognized and used in the assembled residential construction market.There are two main types of prefabricated stair components used in the market for prefabricated residential buildings: one is a prefabricated double-run staircase;the other is a prefabricated scissor ladder.Although with the fiery heat of the prefabricated residential building market,the production and use of prefabricated stair members have been greatly promoted to a new height,but an urgent problem to be solved in the practical application ofprefabricated stair members is also It is placed in front of us,that is,the problem that the prefabricated stair members are generally cracked at the bottom of the slabs under the action of self-weight.According to the investigation,the prefabricated stair members used in the assembly and assembly process are cracked at the bottom of the slabs.The rate is as high as 90%.This problem has brought a lot of influence and inconvenience to the popularization and application of prefabricated stair members in engineering practice.Whether it is the overall aesthetics of the building or the overall completion acceptance of the project,it has been affected to varying degrees,so the prefabricated stair members are in their own weight.The general cracking of the bottom of the slabs under the action has become a common problem that plagues the current assembly-type residential construction market,and effective methods and measures are urgently needed to solve them.On this basis,this paper investigates the cracking load of the bottom plate of the stair step under the static uniform load of the prefabricated slab staircase and the precast girder and the height of the cross section of the precast girders for the stair ladder The influence of the cracking load on the bottom of the plate is compared with the different model parameters of the prefabricated plate stairway and the prefabricated girder type and the same prefabricated stair type through the test and finite element numerical simulation.The mechanical differences between the structural measures are different,and strive to solve or improve the problem that the prefabricated plate-type stair members are generally cracked under the self-weight of the stair step.The idea of this paper is to first obtain the prefabricated stairway test data through field test,then use ABAQUS finite element to build the prefabricated plate stair model for numerical simulation and verify the comparison with the test data.Finally,numerically simulate different prefabricated stair patterns by changing the model type and model parameters.The influence of the cracking load on the bottom plate of the stair step and the different model parameters of the same stair type(different beam stair girder,different slab stair reinforcement ratio,different construction measures)have an effect on the cracking load of the bottom plate of theprefabricated stair step.Finally,based on the results of the comparative analysis of the test and numerical simulation,combined with the common problems existing in the prefabricated stair members of the current fabricated residential building market,reasonable suggestions and solutions are proposed to solve or improve the prefabricated stair members in the current fabricated residential building market.The problem of general cracking at the bottom of the slabs under the action is to achieve the purpose of reducing the cost of the fabricated residential buildings,to improve the industrialization level of the buildings,and to promote the development of the assembled building market. |
PDF Full Text Request