Research On Load-Bearing Performance And Design Method Of Multi-ribbed Composite Wall In Moderate-high Storied Multi-ribbed Slab Structure

Multi-ribbed slab structure is a new structural system, characterized by low-weight, energy-saving, thermal retardation and sound insulation, environmental protection, fast construction, economy and good aseismic performance .Now, staged accomplishments have been achieved in the academic and applied research on the multi-storied multi-ribbed building and moderate-high multi-ribbed building. However, as a new structural and for its complex load-bearing performance, some problems are still needed to be solved, such as the simplified calculation model and the counting methods of bearing capability. The paper is devoted to studying on the multi-ribbed composite wall, which is the main bearing member in multi-ribbed slab structure. On the basis of the previous researches, and through experiments and numerical analysis in detail, the paper focuses on the load-bearing performance, failure modes, integral structure performance and normal section bearing capacity of the moderate-high storied multi-ribbed composite wall under the axial-press, co-action of press, bending moment and shear.The main content is described as follows:1. Five 1/2-scaled model experiments of the multi-ribbed composite walls with one span and one story under vertical load are presented;the load-bearing performance ,failure process and failure characteristic, bearing capacity and deformation performance of the wall under vertical load are analyzed;some factors such as ratio of height to sectional thickness of the wall and load distribution are discussed;the effect of ribbed beams under compression, the contribution of filled blocks to the wall and the axial force distribution among frame columns, ribbed-columns and filled blocks are analyzed, which provide an important support for establishing the calculation formula of axial force bearing capacity of the wall.2. The linear elastic and nonlinear finite element analysis are used to study the load-bearing performance of the wall under vertical load. Aimed at different analysis contents and purpose, different calculating models are proposed, and the rationality and precision of models are proved by test data. Based on linear elastic finite element analysis, the paper suggests influencing factors and numerical value of distribution coefficient of axial force, which provide a reference for structural design of the wall. Meanwhile nonlinear finite element analysis is employed to analyze the stabilization of the wall, and the calculation formula of stabilization coefficient is proposed, which provide an important academic support for establishing axial capacity calculation formula of the wall.3. Two 1/2-scaled model monotone experiments of the walls with two spans and twostories under vertical load, horizontal load and bending moment are presented. Based on the test data, the wall's failure process, failure modes, bearing capacity, deformation performance and the inner force variety of every bearing members are analyzed, which provide an important support for compression-bending capacity calculation formula of the wall.4. The performance of the multi-ribbed composite wall under co-action of press, bending moment and shear is analyzed using finite element analysis. According to "rigid frame-plane substructure" model, and considering the shearing-span ratio, dimension of the wall as parameters, the co-performance between the end frame column and the multi-ribbed composite slab, the distribution and influencing factors of inner force between the end frame column and the slab, the deformation feature of the wall are analyzed by means of linear elastic finite element method, which provide an important support for section design of the wall under a minor earthquake.Considering shearing-span ratio, section dimension and ratio of reinforcement of end frame column, vertical load of the wall as parameters, the load-bearing performance under the vertical, horizontal load and total bending moment are analyzed through nonlinear finite element method where "solid element and combined reinforcing type" model are adopted.. Through the analysis of calculating results to the bearing capacity, deformation features, normal stress of different wall models, the influencing factors of failure modes and shearing bearing capacity, bending bearing capacity of the wall are summed up, and the characteristics of stress and strain in the limit state under compression-bending are put forward, which offer the reference for establishing compression-bending capacity calculation formula of the wall.5. Based on previous test results and numeral analysis, the simplified calculating model and stress curve of the wall in ultimate state eccentric and axial compression are proposed according to the design principle of practicality and simplification, and the practical design formulas of axial and eccentric compression bearing capacity of the wall are provided.6. Based on previous study, the concept design and section design method and aseismic detail requirements of moderate-high storied multi-ribbed slab structure are studied, which are both valuable for structural design theory and practical application of moderate-high storied multi-ribbed slab structure.The originality of the thesis lies in:1. Large-scaled model experiment of multi-ribbed composite wall under vertical load is made and numerical analysis is processed for the first time.Large-scaled model experiment of multi-ribbed composite wall under vertical load are made for the first time;effective and different types of finite element models of the wall are established;the load-bearing performance of the wall under vertical load is carefully studied by experiments and numerical analysis, form which influence factors about the wall's bearing capacity is gained;axial force distribution and stability of the wall under grate earthquake are carefully analyzed for the first time;the calculation formula of stability coefficient is put forward which not only reflects construction characteristics of the wall but also accords with the load-bearing performance, which provide an important support for establishing the calculation formula of axial force bearing capacity of the wall.2. Large-scaled model experiment of moderate-high storied multi-ribbed composite wall under the co-action of press, bending moment and shear are made for the first time.Large-scaled model experiment under horizontal monotonic load are made andapplication of entire moments, construction of loading equipments and methods of loading are put forward and adopted for the first time. According to the test, failure mode, bearing capacity, collapse resistant capacity and stress-strain feature of the wall under vertical and horizontal load are systematically studied;working performance and deformation behavior of the whole wall, member and connecting joint under vertical and horizontal load are sufficiently understood, which provide an important foundation for establishing compression-bending capacity calculation formula of the wall.3. To establish numeric analysis model for multi-ribbed slab wall under the co-action of press, bending moment and shear.Linear elastic and nonlinear finite element analysis models for moderate-high storied multi-ribbed composite wall under vertical and horizontal loads are established. According to the finite element analysis, the co-performance between the end frame column and the multi-ribbed composite slab, deformation character, failure modes and section stress—strain feature of multi-ribbed composite wall under the co-action of press, shear, and bending moment are simulated factually, which can provides more data information so as to understand the bearing mechanics of the wall under the co-action of press, shear, and bending moment accurately.4. To put forward practical design formulas for normal section bearing capacity of multi-ribbed composite wall.Based on the results of test and numeral analysis, practical design formulas of axial and eccentric compression bearing capacity of the wall are provided, and the calculating results are analyzed comparatively with results of test and finite element, thus the design theory of normal section bearing capacity of multi-ribbed composite wall get perfect further.5. Establishing and improving practical design method.According to previous studies, the concept design and section design method of moderate-high storied multi-ribbed slab structure are established and perfected, and the aseismic detail requirements on section design, distributed steel and connection of the wall are definitely put forward. This part has been used in Shaanxi Province Construction Criterion ((Technical specification for multi-ribbed slab structure)) (DBJ/T 61-43-2006) , which are both valuable for structural design theory and practical application of moderate-high storied multi-ribbed slab structure.