Applied Mechanics and Materials Vols. 94-96

Abstract: For difficulties and deficiencies for complex geologic body and structural engineering with FLAC^3D, the three-dimensional complicated model was built by using MIDAS/GTS-FLAC^3D coupling technique, which was based on the Kangjiagou-bridge-Miaoliang-tunnel project crossing the mined-out regions in Liulin section of Qingdao-Yinchuan highway. The interactions between the mined-out regions and surface structures such as the tunnel lining and bridge were analyzed as the following sequence of operations: the mining process step-by-step was performed corresponding to the years, and then the grouting treatment was carried out after mining coal in Kangjiagou, next, Miaoliang tunnel was excavated and Kangjiagou bridge was constructed. The surface deformations under different working conditions were revealed, and the ground subsidence basin characteristics were analyzed. Also, the deformations and forces of key bearing parts of the tunnel lining and bridge structure were predicted in order to guide the engineering design and construction. The above-mentioned results have important theoretical meaning for guiding the similar engineering practice.

Abstract: Considering the strain rate then puts forward the modified uniaxial dynamic constitutive model related to strain rate in concrete-filled square steel tube and the modified calculation results match well with the experimental results. Based on the above conclusion, uniaxial compression performance finite element analysis with different strain rate among 10^-5/s–10^-3/s is completed, the results showed that strain rate can obviously change the dynamic performance of the concrete-filled square steel tube. Through the analysis of the influencing factors of the core concrete compressive strength, it is showed that with the increasing of the strain rate and the improving of concrete strength, the ultimate bearing capacity of concrete-filled square steel tube is higher and the ductility is reduced. With the increasing of stirrup ratio, ultimate bearing capacity is greater and the ductility is enhanced. With the sectional dimensions increasing, the ultimate bearing capacity is greater and the ductility is enhanced.

Abstract: In the background of buildings in coastal area being corroded by salt fog, this paper studies 12 beams of different intensity and protective layers to simulate the real effect of the corrosion for 20 years. Elaborates the phenomenon of enhancement of the concrete compressive strength and the bearing capacity and cracking load of test beams, and makes an indepth analysis on the mechanism of this phenomenon, at the same time the concept of the additional expansion prestress is introduced; a mathematical model of the additional expansion prestress is establish and the computational model of the cracking load is derived.

Abstract: Numerical analysis is effective means to evaluate deep excavation influence in the sensitive environmental condition, and it is key issues to choose the elastic modulus of rock parameters reasonably. Based on the finite element theory, the relation between rock mass elastic modulus reciprocaland and the objective function value is a quadratic function in the elastic zone of multilayer layers, and then the optimal value of elastic modulus is obtained by polynomial interpolation method. Combined with the practice engineering, the elastic modulus of rock mass excavation is back calculated in the sensitive environmental condition and the effects of excavation are evaluated on the surrounding tunnel. The results show that the method is more convenient, and provide a reference for foundation pit construction.

Abstract: According to the structural features and actual load carrying status of externally prestressed profiled steel sheet composite slab, in consideration of the deformation of the whole prestressed structure, the prestressed incremental calculation formula is established with force method and the prestressed incremental calculation formulas for arranging reinforcements in straight line or fold line with deviators; according to the positions of neutral axis, the stress-strain of externally pre-stressed profiled steel sheet and concrete composite slab section is analyzed so as to derive the calculation formulas for the elasticity bending bearing capacity and ultimate bending bearing capacity of the externally prestressed profiled steel sheet composite slab.

Abstract: Impact damage of building structures occurs frequently nowadays, and failure of key components of the structures may lead to the collapse of the whole buildings which could cause serious consequences. Thus, it is necessary to study on the impact resistant performance of the members. The different protective measures against impact loads were examined through the experimental testing in this paper. A tube steel beam with the rectangle cross-section was selected as the tested object. During the experimental testing, the different weight of the drop hammers and the different shapes of the contact surfaces were designed for sake of comparison. The strain history at the middle span of the steel beam under the impact load was measured by a Fiber Bragg Grating sensor. By comparing the strain values, the experimental results show that the composite layer which consists of the rigid and the flexible plate is superior to the single layer which only consists of the rigid plate, and have a better effect for suppression of the dynamic response against the impact loads.

Abstract: Damages correlation of prestressed concrete beam and its safety evaluation have been studied by finite element method. The influences of three typical damages on deflection of beam have been analyzed. The vertical crack damage (VC) has been simulated by pre-crack and contact elements has been set between crack surfaces, the reinforcing steel corrosion damage (RSC) has been simulated by reducing the effective area of the reinforcing steel, and the concrete strength degradation damage (CSD) has been simulated by changing the elastic modulus of concrete based on the relationship between concrete strength and its elastic modulus. Damage correlation variables have been defined, and safety evaluation method of concrete beam based on damage correlation has been discussed. The results showed that: there is a strong nonlinear correlation between VC and RSC, and the beam's safety states are significantly reduced because of the interaction of damages.

Abstract: Based on the analysis of patent protection and strategy of enterprises in Wuhan, this paper, adopting approaches like literature reviewing, diagrammatic presentation and logical reasoning as well as the Smiling Curve theory, reveals that patent strategy is a part of holistic enterprise strategy. This paper also indicates that patent, as the specific resource of enterprises, its strategical planning and implementing plays practical significance in leading enterprises moving to the high value-added sections. Thus, the patent strategies are put forward accordingly including self-owned core patent strategy, paid-transfer patent strategy, patent-purchasing strategy, cross licensing patent strategy,etc. This paper suggests that, driven by patent strategy, more values could be made through transforming to the two ends of the smiling curve, promoting the bottom and right part of the curve and the whole moving upwards so as to create high additional value.

Abstract: This paper puts forward a new strengthening method in case of insufficient shear capacity of concrete beam, i.e. it adopts the after- anchor steel bar to be fixed in the shear area of concrete beam to play the role of stirrup or bent-up steel bar shearing resistance , and makes testal study on this by making test specimens. The results show that compared with the unreinforced construction members, after the reinforcement with this method, the existence of post-anchor stirrup delays the development of cracks, increases the cracking load, reduces the crack width under the same loads, changing the wide and sparse cracks to fine and dense cracks, shows good stress state and greatly improves the shear capacity of beam; considering the test phenomenon that the stress of post-anchor stirrup is relatively lagged behind, in terms of calculation method, this reinforcement method adopts calculation formula of bent-up steel bar shearing resistance of the concrete beam and estimates the bearing capacity after slight improvement, the calculation results being close to the measured values and having a certain emergency capacity; the anchoring of reinforcement materials in this method is featured with good effects, clear transmission and simple construction and a certain pre-stress could be imposed to better develop the feature of high tensile strength of reinforcement materials.

Abstract: In view of the fact that the Z-shaped reinforced concrete column normal section bearing capacity formula has not been clear about the difference stipulation question with other specially column section bearing capacity computation, carries on axial compression-test of the Z- shaped reinforced concrete column with different volume reinforcement characteristic. In this article, established the Z shape column's load - elastic curve, promoted the Z-shaped column normal section bearing capacity formula including section correlation coefficient, and carried on the simulation using the ANSYS finite element software. The result indicated that the ANSYS simulation value was closely with the experimental value and the formula predicted value, and the formula predicted value security, has the high reliability.