Finite Element Analysis of Masonry RVE Homogenization Procedure

Homogenization is one of the most important steps in the numerical analysis of masonry structure, where the continuum is used. A masonry representative volume element (RVE) is formed as the equivalent element of masonry components and it is the most important step in homogenization procedure. The RVE is molded with consideration of the material properties of mortar and brick as well as their interaction separately. In this paper the masonry RVE is simulated with the finite element software ANSYS. The stress-strain relationships of RVE subjected to different types of loading conditions are presented. The equivalent elastic modulus and Poisson's ratio are calculated and the feasibility of finite element method used in the procedure of masonry homogenization is demonstrated.     

Pseudo-Static Test on Seismic Deformation Capacity of Masonry Wall Constrained by Core-Tie-Columns

A new tie column such as core column, named as core tie column, for the substitution of cast in place tie column was used to improve seismic performance of mansonry structures. Pseudo static testes of 11 wall specimens including 6 walls constrained by core tie columns, 2 walls constrained by cast in place tie columns, and 3 walls without constraints were carried out to study the seismic deformation capacity of mansonry walls with core tie columns. The skeleton load displacement curves and the normalized skeleton curves, displacement ductility factors,drift angels of the specimens were analyzed and compared. The effects of the level of vertical compress load, aspect ratio and the wall style on the deformation capacity of the wall with core tie columns were distinguished. It is shown that the constraints effects of core tie columns on masonry wall are effective and the walls with core tie columns have good deformation capacity as those with cast in place tie columns.     

Experimental Investigation on the Aseismic Behavior of Seismic Damage Masonry Wall Retrofitted with Grouting and Steel Hoops

In order to accurately evaluate the aseismic behavior of the seismic damaged masonry pagodas destroyed by Wenchuan earthquake and strengthened after the earthquake, a test was conducted to acquire related parameters on seismic performance from the specimens made by masonry and retrofitted with grouting and steel hoops. Taking a seismic damaged ancient masonry pagoda in Sichuan as a case study, four kinds of primitive specimens are fabricated by simulating the conformation of the masonry pagoda. Then the primitive specimens are destroyed under cycle loads and the damaged specimens are repaired by grouting and steel hoops. Cycle controlling tests are conducted with the specimens and relevant data are acquired. Experimental results showed that grouting combined with steel hoops could improve the ductility and energy dissipation capacity of a seismic damage of brick masonry structure, but it do a little to improve the stiffness of a seismic damage structure. And the cracking load of the repaired masonry is much lower than the original undamaged structure.     

Study on Mechanical Properties of High-Performance Concrete

In this paper the high-performance concretes with 56-day compressive strengths of 60 to 100 MPa (with or without silica fume) have been studied experimentally in order to develop information about the mechanical properties of high-performance concrete. Results and discussions are presented regarding compressive strength gain with time,effect of drying. A linear equation of static modulus of elasticity has been derived.The static modulus of elasticity and Poisson's ratio are calculated by regression with testing data of 20 specimens.     

Mechanical Properties of Marble at High Temperature

为进一步优化超声波提取胡萝卜中β-胡萝卜紊的工艺条件,在超声功率、超声时间、提取温度、物料粒度、料液比及提取次数6个单因素试验结果的基础上,采用二水平部分因子析因设计（2—level fractional factorial design）法,筛选出了影响β-胡萝卜素提取的主要因素为提取时间（p=0．0145）、温度（p=0．0189）、料液比（p=0．0180）和提取次数（p=0．0114）。     

Mechanical Properties of Concrete Cylinders Confined with CFRP Sheets Subjected to Axial Compression

Based on Drucker-Prager criterion with non-associated flow rule, numerical analysis of mechanical properties of concrete cylinders were carried out by using non-linear finite element method. The effect caused by various parameters such as wrap thickness, fiber orientation and concrete strength on axial mechanical properties of concrete cylinders is discussed. The results show that the results calculated by non-associated flow rule conform to that in the test. It is demonstrated that there is significant enhancement both in compressive strength and ductility of cylinders with the increase of wrap thickness. Moreover, the gain in axial compressive strength is observed to be higher for lower strength concrete and be highest in the cylinders wrapped with the hoop orientation.     

Study on Mechanical Properties of Cement Concrete Pavements

The study of the mechanical properties of cement concrete pavements is the base of the structural design of pavement. The existing mechanical models, such as elastic plate system, layered elastic system and so on, are systematically presented. The limitations and merits of various mechanical models are discussed at the same time. The development process of the solution methods for the study on mechanical properties of cement concrete pavements is also presented. The development trend of the study on pavement mechanical properties is given in the end.     

Influence of Alkali-Silica Reaction on Mechanical Properties of Cementitious Materials

The expansion rate of mortars, prepared with active sand and non-active sand, under alkali-silica reaction (ASR) was recorded. The effects of ASR on mechanical properties of cementitious materials were studied by triaxial compression test. The relation between the microstructure of cementitious materials and the mechanical properties was investigated as well. The results showed that there was a little blade crystals gel formed in a local region near the aggregate in materials prepared with non-active sand. For the quantity of formed gel is small, the expansion effects of ASR are limited. Whereas, thick blade crystals gel layers formed near the aggregate when the active sand prepared materials subjected to ASR. Moreover, the reactive products would lead to cracks and then significantly affects the mechanical properties of mortars. Additionally, the results showed that besides the expansion rate,the ultimate compressive strength and the strain are also effective indexes to estimate the influence of ASR.     

基于Workbench杏壳力学特性分析

为提高杏核的破壳质量,对杏核壳体的力学性能进行研究。考虑到杏核表面有凸起的棱筋及壳体不同区域厚度不同对力学特性的影响,通过威布三维Reeyee扫描仪对1/2赛买提杏核壳体进行扫描,利用SpaceClaim软件对杏核壳进行模型修复,得出杏核壳体的三维分析模型;运用ANSYS Workbench对1/2杏核壳体进行3种方式加载云图分析,得出最佳的破壳方式,然后通过试验验证模型分析的准确性。结果表明：赛买提杏核沿不同方向施压所需的破碎力有显著差异,其中沿Y 轴方向所需破碎力最大,为856 N,变形量为2.48 mm,杏仁破碎率为0;沿X=Z 轴方向所需破碎力最小,为398 N,变形量为0.41 mm,杏仁破碎率为21.8%;沿X 轴方向施压所需的破碎力为426 N,变形量为1.08 mm,杏仁破碎率为0。验证试验结果与模型分析的结果一致。因此,通过扫描仪建模更能准确反映杏壳的表面特征,相对于Y、X=Z 轴,沿X 轴方向施压更合适。本文可为杏核破壳机械的设计提供参考依据。     

Experimental Analysis of Seismic Performance of Strengthening Frame-supported Reinforced Concrete Masonry Short-leg Shear Wall Structure Damaged by Earthquake Using the Sub-structure Pseudo-dynamic Test

Based on the damage assessment and strengthening scheme of the full-scale model which is the three-floor frame-supported reinforced concrete masonry short-leg shear wall structure, the strengthened model is tested using the substructure pseudo-dynamic testing method. The applicability of the proposed strengthening technique for the building damaged by earthquake is discussed. Thus, the seismic performance of the strengthened model is proposed to seek the strengthening technique for the structure damaged by earthquake, and it provides important reference for the post-disaster reconstruction after Wenchuan earthquake.     

Experimental Analysis on Mechanical Properties of Corroded Stud Shear Connectors

Four series stud push-out specimens were conducted to study static mechanical behavior when stud shear connectors of composite beams were corroded. Firstly, the studs were manually rapidly corroded by electrochemical methods, and then a static load test was performed on them. Test results show that when corrosion occurs at stud rod especially close to combined surface, the ultimate bearing capacity reduces most by 18%, slip under the same load increases, and slip relative to the ultimate load reduces most by 12%. When corrosion occurs at the large end of stud, it has little effect on ultimate bearing capacity of push-out specimens, but deformation performance of stud shear connectors is affected seriously.     

Quasi -static Mechanical Properties of SFRC under Uni -axial Compression

Using WAW-2000 a multifunction servo-controlled testing machine,uniaxial quasi-static compression experiments for the steel fiber reinforced concrete(SFRC) were conducted with three strain rates.The volume fraction(V_f)of SFRC ranged from 0% to 3%,and the matrix was C50 concrete.The whole stress-strain curves of matrix and SFRC were obtained,and the results showed that with the increase of V_f,the compressive strength increased slowly,while the toughness increase quickly.With the increase of the strain rate,the strength of SFRC increased,but the toughness decreased,and the more the Vf,the less decreasing of the toughness.The results also showed that the elastic modulus and Poisson's ratio of SFRC were not sensitive material parameters,and with the increase of V_f,the former raised slightly and the latter decreased a little,respectively.A well suited numerical expression of the compressive stress-strain curve applicable to SFRC was put forward.     

牡丹永生花软化护形后力学特性研究

为解决真空冷冻干燥后的干花容易断裂、破碎,且易吸潮不利于贮藏运输的问题,以经过真空冷冻干燥后的牡丹干花为材料,利用超声雾化技术对其进行软化护形处理,并利用质构仪测量其软化护形后牡丹干花的刺穿强度和拉伸强度。结果表明,经过软化护形液处理过后的干花其刺穿强度和拉伸强度明显大于未处理的干花,其力学特性也优于后者。     

The Nonlinear Analysis of Brick Masonry

On the basis of analyzing and summarizing the recent theoretical researches on constitutive models and failure criteria for brick masonry, a combination of a useful constitutive model with a reasonable failure criterion is used for describing the behavior of brick masonry under the loading in plane. A finite element program of nonlinear analysis is compiled. The predicted results are found to be in good agreement with Andreau's results.     

Experimental Analysis on the Mechanical Properties of Concrete Composite Slabs with Precast Prestressed Rectangular Rib Panels

For the convenience of industrialized production and site operation,specification design of PPCRP (precast prestressed concrete ribbed panels) is discussed. In order to obtain ultimate bearing capacity,bending rigidity and crack resistance,four PPCRP with two types of spans are studied,and the results show that PPCRP can satisfy the requirements of bearing capacity in construction phase and can serve as stay-in place formwork. To verify the mechanical property,shear behavior on contact interface of composite member and moment redistribution factor of continuous composite member,two single-span composite members and one two-span continuous composite member are studied. It is indicated that computational method for bearing capacity of composite member can be the same as cast-in-situ concrete slab. Besides,section strain analysis for composite member in two-loading is conducted,which suggests that thickness of bottom board can be used as calculated height with the consideration of two-loading.