Shan Suo Zheng

Influence of Silica Fume on High-Performance Concrete

With the improvement of concrete materials and the emergence of new materials, adding silica fume to high-performance concrete (HPC) has been one of the important ways in concrete technology. In this paper, through experimental study on the mechanical performance of HPC with 5%, 10%, 15% and 20% silica fume replacing cement for different water-binder ratio, along with polycarboxylates high performance water-reducing admixture, silica fume has large effects on 28d compressive strength, split tensile strength and flexural strength of the HPC. Meanwhile, due to the different level of water-binder ratio, the relationship between split tensile strength, flexural strength and compressive strength is also obvious linear.

Analysis of Storey Damage Effect Factors of SRC Frame-RC Core Tube Hybrid Structure under Cyclic Loading

Based on the general finite-element software ABAQUS, the FE model of 30-story SRC frame-RC core tube hybrid structure is built up. The maximum story drift angle of the structure under cyclic loading can effectively characterize the changes in storey damage. With the new achievements on damage effect factors, the relation between storey damage and component damage of various types and influence of the main design parameters on the storey damage law are analyzed. It is found that storey damage degree is more serious with the increase of stiffness character value and shear wall depth-thickness ratio, but the effects of both of them are gradually weakened and the change range of it is really small. Research will provide theoretical support on the building of hybrid structure damage model under earthquake excitation.

Fuzzy AHP GA-Based Optimization Design of SRC Beam

Genetic algorithms (GA) are very effective at finding optimal solutions to a variety of problems. This innovative technique performs especially well when solving complicated real-world problems. Therefore, this paper aims to use the fuzzy analytical hierarchy process (AHP) GA approach to optimize SRC beam. In the process of optimization, the matlab toolbox with GA is used. To increase the performance of the genetic-based approach for optimization problems, the design constraints related to member stress, bending moment etc are described by using fuzzy set theory. Finally, a example for beam optimization is presented. The example shows that the approach is flexible enough to deal with optimization of SRC beam.

Optimization Design of Steel-Concrete Composite Beams Considering Bond-Slip Effect

The optimization methodology of the steel-concrete composite beam was proposed in this paper. The objective function is the cost of the composite beams, and the design variables are the geometry parameters, including height and width of the concrete deck, as well as thickness of the steel flange and web. The constraint conditions are main requirements stated in Chinese code for the design of composite beam, reasonable calculating theories and indispensable constructions, as well as some mature and consistent conclusions confirmed by experimental studies. Stiffness reduction coefficient is used to consider the effect of bond-slip effect between concrete and steel when calculating the beam deformation. The optimization for composite beam under uniform loads is given as a demonstration example finally. The methodology proposed in this paper should be useful for obtaining the solution of this kind of optimization problem.

Dynamic Damage Analysis of SRC Frame Structure under Earthquake Action

Structures may enter into nonlinear stage under strong earthquake, so precise prediction of nonlinear behavior for building structure in earthquake is important which can assess the earthquake resistance safety of structures accurately. The exact numerical analysis model is required in actual engineering. In this paper the concept of nonlinear dynamic damage is introduced in steel reinforced concrete (SRC) composite structure, based on the theory of continuous damage mechanics. The damage variable is defined and computed by effective plastic strain of material, furthermore, concrete dynamic constitutive model is derived which considered plastic strain of material. Finally, the damage dynamic balance equation is established. Via comparison with test results of a three-story, two-bay SRC frame model which is tested on a shaking table, it is shown that the results of numerical analysis agree well with test results, indicating that the nonlinear dynamic balance equation is capable of describing the dynamic response of SRC frame structure with satisfactory accuracy. The research supplies theoretical basis for the seismic behavior analysis of SRC high-rise buildings.

The Fuzzy Evaluation of Compatibility between PC-HPWR Agent and Cement

To evaluate the compatibility between polycarboxylates high performance water-reducing admixture and cement, the initial Marsh-time or fluidity(T), loss rate of fluidity as time(FL), saturation point(P), setting time(ST) and bleeding rate(R) are considered simultaneously. Making the comparisons of these parameters between tested concrete and reference cement, the corresponding membership functions are established, and using the fuzzy mathematical evaluation method based on the program Matlab, breaking the limitation of reference cement, the more comprehensive and accurate evaluation can be made.

Seismic Fragility Analysis of SRC Frame Structures

With the rapid development and extensive application of SRC (steel reinforced concrete) frame structures, the study on seismic fragility of SRC structure under earthquakes seems rather important. The seismic fragility of the SRC frame structures is studied by the method of Incremental Dynamic Analysis (IDA) in this paper. IDA method is conducted on 9 storey SRC frame structure to obtain the IDA curves of this model. Meanwhile, the seismic fragility of the model is analyzed to get the fragility curve. The result shows that IDA can describe the quantitative relationship between the exceeding probability of different states and damage degree of the target.

Study on Fiber Element Used for Simulate SRC Component

The existed research shows that when SRC component is under stress, there is bond-slip happened between shape steel and concrete. And the bond-slip have a certain influence on the bearing capacity of SRC component, when component is loaded to ultimate load, the bearing capacity descends quickly because of the effect of bond-slip between shape steel and concrete. Finite method of fiber finite element is a useful way to simulate this kind of composite components, but it ignores the behavior of bond-slip between shape steel and concrete. So building a bond-slip formula for fiber element to simulate SRC component has a practical significance. It’s not only gets more precisely calculated results, but also make the simulation of failure model close to the practical situation. In this paper, in order to add bond-slip effect into fiber element theory, a formula was set up to adjust stress of steel material, which was based on constitutive equations of our bond-slip tests. The method was programmed in OpenSees and used to simulate tests of SRC frame under cycling load, the simulate results shows that the method suggested in this paper is an effective way to express behavior of bond-slip in SRC component.

Study on the Floor Damage Model of Hybrid Structure under Seismic Excitation

Structural destroy is a development process that damage is accumulated gradually under earthquake, and the partial destruction leads to the overall damage, even structural collapse finally. Based on the damage model of beam, column and shear wall, the damage is studied from the component level, the most important design parameters which include bending strength ratios of beam to column, xial compression ratio and stiffness characteristic value are researched. Then the finite element numerical analysis software ABAQUS is used to analyze the influence of various component damage on seismic performance of floor. Finally, this paper adopts Weighting Coefficient Method to establish a reasonable model for the floor damage evaluation .It proves that the model can reflect the relationship between component damage and floor damage.

A Multiaxial Damage Statistic Constitutive Model for Concrete

In order to apply the uniaxial damage evolution equation that established with the variable of strain to the multiaxial damage quantitative analysis, this paper bases on the Hsieh-Tang-Chen four-parameter failure criterion and adopts the way of making the triaxial equivalent strain combining with the uniaxial damage evolution equation to analyze and deduce the uniaxial damage evolution equation of SRHSHPC, and which is expanded to multiaxial condition as well. A function considered triaxial stress state and a related correction value are suggested, then, improving the damage evolution equation from triaxial to multiaxial form, finally proposing the multiaxial damage statistic constitutive equation for concrete, taking numerical simulation with the complete decoupling method and the result shows that the model is effective.