Applied Mechanics and Materials Vols. 166-169

Abstract: Many materials show viscoelastic properties under long term load, because of the complexity of viscoelastic problem, it is not enough for describing the characteristics of material and structure with classic viscoelastic model. The stress-strain constitutive relationship is described by fractional derivative viscoelastic model, the radial displacement and stress of thick-walled cylinder under internal pressure are obtained by using Fourier transform and the properties of fractional derivative, and we also investigated the steady state response of compressible fractional derivative viscoelastic thick-walled cylinder.

Abstract: In order to study on the flexural performances of beams strengthened with external bonded carbon fiber reinforced polymer（CFRP）sheets, nonlinear analysis is carried out by using software ANSYS. The results show that a reasonable finite element model, using a reasonable solution strategy can be a good simulation of CFRP flexural performance of reinforced concrete beams, and finite element analysis results with the experimental results have good consistency .The beams reinforced by carbon fiber polymer，the capacity of flexural resistance increased with the numbers of carbon fiber paste sheets, reinforced components of flexural capacity significantly improved, but the extent of its increase is not proportional with the numbers of carbon fiber paste sheets.

Abstract: By experimental, study on the elastic modulus and the splitting tensile strength together with the influence of the splitting tensile strength with different water-cement ratio, sand rate and water quantity , and the relational formula between the splitting tensile strength and the elastic modulus was summarized by regression analysis.

Abstract: To commemorate the 100th anniversary of the Xinghai Revolution, the government of Wuchang district in Wuhan City intends to rehabilitate rain-wind corridor, feudal pavilion and the city walls. After access to historical data, site survey, mapping, photographing and measuring, the rehabilitating engineering program of rain-wind corridor, feudal pavilion and the city walls of the Wuchang Uprising Gate is achieved. In the fourth year of Hongwu (1371), Ming dynasty, Zhou Dexing, the duke of Jiangxia, built Wuchang city on the basis of Yingzhou city of Tang dynasty. Wuchang city has large scale. In Ming and Qing dynasty, it was the legacy of county, town, city and province. Its diameter from the east to the west was of 2.5 km, with 3 km from the north to south. The thickness of wall foundation is 22.44 m, with top thickness 17.82 m. Nine gates were designed for the ancient city. The Uprising gate, one of the nine gate of the Wuchang ancient city, was opened to the south and also the busiest gate for entering the city. New Army Engineering Battalion of Hubei took the lead and fired the first shot. And then they occupied Zhonghe Gate and Chu Wangtai to welcome the South Lake artillery, Ma team and other revolutionaries.

Abstract: It is well known that the bonding failure between concrete and externally bonded CFRP strips sets in where high shear forces and high bending moments occur. Despite this knowledge, experimental and theoretical studies had been exclusively focused on the bonding failure modes at the end of the CFRP-strip. This paper deals with strengthening of RC two-way slabs with CFRP strips bonded to the tensile face. It focuses on the bonding failure by dealing with an experimental study. The CFRP-strips strengthened slab test presents a failure mode with debonding of the external CFRP strips from the slab.

Abstract: Structural deterioration is becoming a major problem when considering long-term performance of infrastructures. The actions of corrosive environment, repeated loading and concrete cracking lead to structural degradation, whereas externally bonded carbon fiber reinforced polymers (CFRP) may increases structural performance. In the present paper, a theoretical model based on fatigue performance of materials and stress analysis for cross-section is proposed in order to analyze the fatigue damage of corroded reinforced concrete beams strengthened with CFRP under repeated loads. Further, fatigue life is predicted by applying this method, and the method is evaluated by test results.

Abstract: When bend-up bars are placed for the shear strength of reinforced concrete beams, the design calculation is tedious with traditional methods. In this paper, an improved method for the row number of bend-up bars was brought up. And the calculating examples were given to compare with the traditional methods. The results show that the improved method in the paper is simpler, more intuitional, and easier to compute without errors.

Abstract: The ground surface above the gob appear movement and deformation after the coal seam was mined, the movement and deformation of the ground surface influence the buildings on different levels. The destructive effect of the subsidence area must be considered if building brick-concrete structure buildings in subsidence area. Setting the ring beam is a common rigidity protection measures, it can improve the integrity of the building, the ring beam usually combined with the structural columns to form the framework of the building so that the building still function properly when suffered with the subsidence and deformation of the ground surface. Through the study on cases, get the relationship between the ground surface deformation and the ring beam reinforcement and provide reference for the decision making and practice of new construction in mining area.

Abstract: Based on eccentric compressive experiments of reinforced concrete column strengthened with jacketing method, the paper calculated and analyzed jacketing reinforcement of RC eccentric compressive column subjected to fire. The calculation procedure of residual load capacity of compressive member after fire was put forward according to temperature distribution at column section. To distinguish tensile or compressive failure of RC column, the formulas of relative balanced depth of compressive zone of jacketing section were deduced as well as the corresponding applied calculation method of norm section load capacity was presented under the second loaded stage. In addition, the reinforcement design and construction of one fire damaged building was conducted in terms of this paper’s method. The good running status of strengthened columns for many years validates the applicability of this method.

Abstract: Rational evaluation for stress increase of unbonded tendon at ultimate is the basis to exactly compute flexural load bearing capacity of unbonded prestressed concrete beams. Moment-curvature nonlinear analysis method is adopted to compile programs for calculating stress increase at ultimate in unbonded prestressed continuous beams. The precision of the method is proved by comparing results of 16 experimental two-span unbonded prestressed continuous beams to the prediction value of stress increase at ultimate. Based on the simulation analysis, law of the influence of some basic factors to stress increase at ultimate in unbonded tendons in continuous beams is obtained, such as non-prestressed reinforcement index, prestressed reinforcement index, ratio of span to depth and loading type. Then formulas for calculating stress increase at ultimate in unbonded tendons in prestressed concrete continuous beams were established.