Study On Stressing State Modeling And Evolution Characteristics Of Concrete And Masonry Structures

Concrete and masonry structures play an important role in civil engineering and other fields.However,there are two classical problems: the first one is the uncertainty in the ultimate loads of concrete and masonry structures;the second one is the inaccuracy design values in structural bearing capacity,which leading to theories reforming.In recent years,the structural stress states theory and structural failure laws provid a new way to overcome these problems.To overcome these problems,this paper proposes the state variable construction methods based on the typical test data,in which the evolution characteristics is also been analyzed.Moreover,the failure starting points and elastic-plastic branch points of two concrete structures and two masonry structures are revealed,resulting in a new reference for the advanced structural design regulations.The main research work of this paper and some conclusions are as follows:1)The test strain data of spirally reinforced concrete column(SRC)under axial compression load are converted into generalized strain energy density as the basic state variable.The overall force state model of SRC columns and its characteristic parameters are constructed by applying the basic state variables.The method of constructing the force state sub-mode and its characteristic parameters of SRC column components(hoop,longitudinal reinforcement and concrete)from the original strain data is also proposed.The Mann-Kendall criterion is applied to discriminate the characteristic points on the evolution curve of the characteristic parameters of the force state of SRC columns to reveal the starting point of failure of SRC columns,according to which the failure load of SRC columns is defined.And the evolving characteristics of the force state mode and force state sub-mode of SRC column are examined to verify the jump characteristics of the revealed force state at the failure starting point.An attempt is made to establish the formula for calculating the failure load of SRC columns.The revealed failure starting point of SRC columns provides a reference for the improvement of SRC column design.2)Based on the test displacement data of open cavity and solid masonry wall slab under out-of-plane transverse uniform load,the method of constructing the generalized force work around the displacement measurement point area is proposed and taking it as the basic state variable.Further,the method of constructing the force state model of the wall slab and its characteristic parameters with this state variable is proposed.The Mann-Kendall criterion is applied to discriminate the characteristic points on the evolution curve of the force state parameters of masonry wall slabs,which reveals the failure starting point and the elastic-plastic branch point of masonry wall slabs.The evolution characteristics of the masonry wall panel force state modes in the form of increments,correlation and differentials are examined,verifying the trending transformation characteristics of the force state modes at the characteristic points.The elastic-plastic branch point load of masonry wall slab as the load carrying capacity design value is compared with the load carrying capacity design value of masonry wall slab based on yield line theory,and the difference between the two in terms of reasonableness and cost effectiveness is explored.3)Based on the test strain data on the vertical reinforcement,horizontal reinforcement,and masonry wall surface of Reinforced masonry shear(RMS)under in-plane transverse low circumferential reciprocal load,a method is proposed to characterize the force state applicable to low circumferential reciprocal load.The strain data can be divided into: the amplitude strain data at amplitude load and the residual strain data at zero load,and the force state modeling analysis can be performed separately.The strain data at amplitude load are converted into generalized strain energy values as the basic state variables,thus constructing the sub-models and characteristic parameters of vertical reinforcement,horizontal reinforcement and masonry wall surface,which in turn constitute the stress state model and characteristic parameters of the RMS wall as a whole.The Mann-Kendall criterion is applied to discriminate the characteristic points on the evolution curve of the characteristic parameters of the force state of the RMS wall,which reveals the characteristics of the failure starting point and the elastic-plastic branch point of the RMS wall.The evolution characteristics of the overall force state mode of the RMS wall and the force state sub-mode of its components are examined,and the jump characteristics of the force state mode at the characteristic points are verified.Similarly,the force state modeling analysis of the residual strain data yields results consistent with the amplitude strain data modeling analysis.With two representative moments(zero load and amplitude load)in the same loading process,the common characteristic points are screened out,indicating the inevitability of the evolution characteristics of the force state of RMS walls,which provides reference and reference for the design of seismic bearing capacity of RMS walls.4)Based on the test strain data of the concrete airport(CA)road surface under two kinds of traffic loads,normal and overload,the methods of constructing state variables are proposed.The state variables thus construct enable the force state patterns and characteristic parameters as next step by presenting the evolution law of CA road surface force state.These state variables are applied to construct the CA road surface force state patterns and their characteristic parameters under normal traffic load(north zone of the road surface)as well as under overload traffic load(south zone of the road surface),thereby applying the slope increment determination criterion to identify the characteristic points on the evolution curve of the CA road surface force state characteristic parameters.The characteristics of the failure starting point and elasto-plastic branch point of CA road surface under the two loading conditions are revealed,so that the corresponding number of offset mode loading and number of cyclic loadings are determined.The evolution curves of the CA road surface stress pattern with the number of offset mode loading and cyclic loading are examined,and the trend transformation of the CA road surface stress pattern at the characteristic points is verified.For the north and south surfaces of the CA roadway,the evolution characteristics of the stress state on the upper and lower surfaces are investigated,and the failure mechanism of the roadway is discussed.The revealed CA surface failure starting point and elastic-plastic branch point provide new references for the design and safety assessment of CA surfaces.In summary,this paper applies the proposed force state modeling analysis method to reveal the evolution characteristics of the structural force state from the four structural test data that traditional structural analysis fails to reveal.It provides a new reference for solving the two classical problems mentioned above and enriches the development of the theory and method of structural stress state analysis.Meanwhile,the proposed modeling analysis method provides a reference for the modeling analysis of the force state of other structural test data.