Advanced Materials Research Vols. 163-167

Abstract: The dynamic compressive experiments of cubic concrete specimens under various biaxial equal proportion loading were preformed. The biaxial equal proportion stress in the tests were kept constant at 1:0, 1:0.5 and 1:1, respectively, and the tested strain rate ranged from 10−5/s to 10−2/s. Based on the experimental results, the influence of the strain rates on compressive characteristics of concrete under various biaxial stress ratios were researched. The unified strength criterion in terms of principal stress space considering the influence of strain rates and biaxial stress ratio is proposed. The fitting curves by the present strength criterion agree well with experimental data.

Abstract: A new calculation model of stagger-joint assemble is presented. The model can reflect three ways to transfer shear force between adjacent rings. To simplify the calculation model, a friction shear contact element is coded on ABAQUS secondary development platform and the nut of bolt is embedded in the segment. Using the model to analysis the Tunnel Through Yellow River, the results show that the integral rigidity of the lining structure improve obviously and the local modify effective have an impact on the adjacent area near ring-joint surface more than away from area.

Abstract: Flexible pavements comprise a majority part of highways in china. Many highway bridges are constructed in these highways. These primary highway bridges are subjected to the same heavy loading as the conventional asphalt pavement, but caused much more significant damage than the conventional asphalt pavement. As hot-mix asphalt (HMA) is a visco-elastic material and the all around environment is different between road pavement and bridge deck, the structural or load-carrying capacity of road pavement and bridge deck is different. Thus, to accurately determine in situ strength characteristics of flexible pavement, it is necessary to predict the temperature distribution within the HMA layers and find the difference between road pavement and bridge deck. The majority of previously published research concentrated on pavement temperature prediction. To confirm the bridge deck temperature profile, observing the temperature at bridge deck and road pavement for two months. Compared with the temperature profile of bridge deck and road pavement, find the difference between them. Then some daily temperature prediction models are analyzed and develop a modified double-sine model to simulate the surface temperature variation of bridge deck.

Abstract: A 6-story R.C. office building had a plan typical of a frame design, but a beam column design procedure was used. Working Stress Design method was used. Severe cracking ranging in size from 5 – 20 mm. A comprehensive study of the design drawings, site and laboratory testing was conducted on structural members to determine the cause and suggest the remedy.

Abstract: In this paper, the extended finite element method (XFEM) is used for a discrete crack simulation of concrete using an adaptive crack growth algorithm. An interface model is proposed which includes normal and tangential displacements and allows the transfer of shear stresses through the interface. Different criteria for predicting the direction of the extension of a cohesive crack are conducted in the framework of the XFEM. On the basis of two examples, a comparison between the maximum circumferential stress criterion, the maximum energy release rate and the minimum potential energy criterion with experimental data has been carried out. The considered numerical simulations have confirmed the flexibility and effectiveness of the XFEM for the modelling of crack growth under general mode I and mixed-mode loading conditions.

Abstract: A practical calculation method of considering the P-Δ effect is introduced. According to the lateral frame, the calculation model and the action load of calculating the P-Δ effect are established. The model characteristic is that the shear force of the lateral displacement member is statically, and the internal force of the first-order analysis is the same as the original structure. The effects each other of each column in the same layer are analyzed, the equivalence coefficients of embodying the P-Δ effect are deduced, the nonlinear analysis becomes the linear analysis. The internal forces are calculated by using no-shear moment distribution method.

Abstract: An industrialized multi-layer precast concrete building with middle-joint beams and columns frame system has been developed by China VANKE CO., LTD. The building is the first industrialized multi-layer precast concrete building for experimental purpose in China. A middle-joint beams and columns method has been utilized with beams and columns split in the middle place. The whole frame structure is then integrated into a unity through precast beams, precast columns, and reliable cast-in-place column-column and beam-beam joints. This paper presents the key points and difficulties during the building design process, introduces the structural design of column-column and beam-beam joints, and analyses the advantages and weaknesses of middle-joint beams and columns frame system.

Abstract: Prediction of internal stability for segmental retaining walls reinforced with geogrid and backfilled with residual soil was carried out using statistical methods and artificial neural networks (ANN). Prediction was based on data obtained from 234 segmental retaining wall designs using procedures developed by the National Concrete Masonry Association (NCMA). The study showed that prediction made using ANN was generally more accurate to the target compared with statistical methods using mathematical models of linear, pure quadratic, full quadratic and interactions.

Abstract: The reinforced concrete members are designed to fail in flexural member to behave ductilely. Also the failure doesn’t impose on columns but beams. But according to the plastic collapse mechanism, the plastic hinge potentially developed at the bottom of the RC column near the base of the structure after flexural yielding. These columns are generally dominated by shear which led to sudden failure in post yielding region because of its relatively short span-to-depth ratio, so special care is needed. The deformability of column with short span-to-depth ratio is small compared with larger span-to-depth ratio column under reversed cyclic loading. Therefore the design of these kinds of RC columns necessitates the prediction of both the shear strength after flexural yielding and corresponding ductility of such members. Ten RC columns with varying axial force ratio and shear reinforcement ratio were tested under monotonic and reversed cyclic loading. The most affectable factor to column behavior was the axial force. The result indicates that concrete contribution to shear resistance in the plastic hinge region and axial strain were decreased as axial force.

Abstract: In connection with the more special paving conditions on deck pavement of Wei He (yellow river) Steel Bridge in Xi`an, various pavement plans have been analyzed by material test methods and mechanical simulation methods. Based on the research and construction of deck pavement in some built steel bridges, Combining our existing equipment and technology at asphalt concrete deck pavement, obtain better pavement performance program as a design. And introduced some issues to which should pay more attention in the implementation of critical control.