Simplified method of analysis of adjacent precast “deck free” concrete box beams used in accelerated bridge construction

The prefabricated bridge is common method in construction since it provides controlled environmental conditions and long-term durability. These adjacent precast box beams are placed side by side with 15mm gaps, the top flanges connected with longitudinal shear keys poured on-site to assist in truckload distribution. Since the concrete-filled joints provide transverse shear rigidity, the load transferred from one beam to another takes place through transverse shear. A parametric study is conducted to investigate the accuracy of simplified analysis method in CHBDC for shear-connected beams to the adjacent box beams. A 3D finite-element was conducted on a wide range of box beams to obtain their magnification factors for moment and shear when subjected to truck loading. The obtained results were correlated with CHBDC and a more reliable simplified equations for distribution factors was developed. Special attention was given to the limitations of CHBDC simplified method and how it can be revised to include the adjacent box-beam.

Simplified method of analysis of adjacent precast “deck free” concrete box beams used in accelerated bridge construction

The prefabricated bridge is common method in construction since it provides controlled environmental conditions and long-term durability. These adjacent precast box beams are placed side by side with 15mm gaps, the top flanges connected with longitudinal shear keys poured on-site to assist in truckload distribution. Since the concrete-filled joints provide transverse shear rigidity, the load transferred from one beam to another takes place through transverse shear. A parametric study is conducted to investigate the accuracy of simplified analysis method in CHBDC for shear-connected beams to the adjacent box beams. A 3D finite-element was conducted on a wide range of box beams to obtain their magnification factors for moment and shear when subjected to truck loading. The obtained results were correlated with CHBDC and a more reliable simplified equations for distribution factors was developed. Special attention was given to the limitations of CHBDC simplified method and how it can be revised to include the adjacent box-beam.

Longitudinal Deformation Model and Parameter Analysis of Canal Lining under Nonuniform Frost Heave

Due to the unique hydrothermal environments, the frost heave failure of the concrete lining of water conveyance canals in cold regions is still frequent. The deformation of lining after frost heaving and the stress distribution calculated by the mechanical model can be the reference for the lining design. However, previous research mainly focused on the mechanical model of the cross-section while having little attention for the longitudinal nonuniform frost heave damage. In this study, a mechanical model of the bottom lining under the nonuniform frost heave deformation is built based on the Euler–Bernoulli beam and the Pasternak foundation model, and the analytical solution of the model is obtained. The internal stress of the lining is analyzed during the changes of subgrade coefficient, shear rigidity, transition section length, and frost heave amount inside the model. Also, the calculation process is proved to be correct. The result shows that dangerous cross-sections are at the start and the end of the transition sections. The maximum normal stress and the tangential stress increase when the subgrade coefficient and the frost heave amount increase and the shear modulus and transition section length decrease. The frost heave amount in the frozen ground subgrade increases constantly, while the temperature decreases, but at the same time, the shear rigidity of the subgrade increases with it. The former increases the stress of lining, and the latter decreases it. Therefore, during the frost heaving process, the internal force of lining is coupled with these two elements. By analyzing a water conveyance canal lining under the nonuniform frost heave in the Xinjiang Tarim irrigation district, the maximum normal stress of the dangerous lining cross-section is greater than its tensile strength when the transition section length smaller than 7 m at the frost heave amount is 0.031 m.

Determination of corrugated core sandwich panels elastic constant based on three different experimental methods and effect of structural integrity on flexural properties

This study deals with the investigation of flexural stiffness and transverse shear rigidity in the direction of corrugation of the integrated and non-integrated corrugated core sandwich panels with the rectangular core. The non-integrated sandwich panels were reinforced with conventional 2-D fabrics in which resin provides the bond between core and skins. The integrated sandwich panels were reinforced with 3-D weft knitted fabrics in which bonding of the core wall to skins was carried out by combined efforts of knitted loop and resin. Using weft knitting technical capabilities, samples of the integrated and non-integrated structures were manufactured with the uppermost degree of resemblance in terms of geometry and mass. Flexural stiffness and transverse shear rigidity of the structures based on the known and unknown facing modulus of ASTM D7250 standard and Nordstrand–Carlsson methods were calculated. The estimated elastic constants based on unknown facing modulus and the Nordstrand–Carlsson methods were found to be highly compatible. However, the unknown facing modulus method is prone to disclose the statistical significant differences between the elastic constants of the structures with fewer tests. Regarding the unknown facing modulus method, it was found that the flexural stiffness and transverse shear rigidity of the non-integrated structure in the direction of corrugation were higher than those of the integrated structure. Results also indicated that the load-carrying capacity in the direction of corrugation was significantly higher in case of the non-integrated rectangular core structure compared with that of the integrated structure.

THE RIGIDITY OF THE EXTERNAL WALL PANEL WITH OPENING OF RESIDENTIAL BUILDING I-515/5 SERIES IN CASE BIAS

There were a number of characteristic damages and defects in typical panel houses when examine, one of which are tilts and biases of wall panels. The stiffness of the wall panel with the opening of residential building I-515/5 series has been determined at a given bias in its plane. The panel was calculated numerically using a nonlinear deformation model by the finite element method and analytically. The software package, LIRA-SAPR 2017, was used in this investigation. The calculation was carried out taking into account the nonlinearity and material creep. As a result, the fields of normal and shear stresses in the panel were obtained and the shear rigidity was calculated. The analysis of the obtained results showed that a possible decrease of the actual stiffness of the panel should take into account against the calculated stiffness was obtained according to the standards.

Rigidity calculation model for transverse joint of prefabricated utility tunnel based on physical guidance

The rigidity calculation model for transverse joint of prefabricated utility tunnel is established by Midas FEA software based on physical guidance.Taking the prefabricated multi-utility tunnel of South Kemugong road of Guangzhou Intelligent City as the experimental object, the position of its transverse joint is analyzed from the aspects of construction and internal force. Midas FEA is used to establish and analyze the three-dimensional model for the transverse joint of the utility tunnel, and the calculation parameters, boundary conditions and loading methods of the materials are obtained, so that the calculation models for the bending and axial rigidity of the transverse joint are established.The results show that the theoretical calculation value of the model is consistent with the experimental value, and it can accurately describe the deformation and internal force state of the joint in the whole process of stress. The shear rigidity of the transverse joint is 3.524×106 kN/m and the flexural rigidity of transverse joint is 1.001×105 kN×m/rad under the condition of 500 kN/m horizontal axial force per linear meter.

Fuzzy Logic Method for Predicting the Effect of Main Fabric Parameters Influencing Drape Phenomenon

The main aspect of this research was to predict the drape parameters and describe clearly the drape phenomenon using fuzzy logic method. Forecasting features allow manufacturers to save time and improve their productivity. The bending rigidity, (in warp, weft, and skew direction), shear rigidity, and weight of fabric samples were used as the key input variables for the model, whereas drape coefficient, drape distance ratio, folds depth index, and node number were used as output/response variables. The results show that changing the values of fabric parameters significantly affected the fabric drape and a representative correlation values were found between the experimental values and those calculated by the fuzzy system.

Explaining the low-frequency shear elasticity of confined liquids

Experimental observations of unexpected shear rigidity in confined liquids, on very low frequency scales on the order of 0.01 to 0.1 Hz, call into question our basic understanding of the elasticity of liquids and have posed a challenge to theoretical models of the liquid state ever since. Here we combine the nonaffine theory of lattice dynamics valid for disordered condensed matter systems with the Frenkel theory of the liquid state. The emerging framework shows that applying confinement to a liquid can effectively suppress the low-frequency modes that are responsible for nonaffine soft mechanical response, thus leading to an effective increase of the liquid shear rigidity. The theory successfully predicts the scaling lawG′∼L−3for the low-frequency shear modulus of liquids as a function of the confinement length L, in agreement with experimental results, and provides the basis for a more general description of the elasticity of liquids across different time and length scales.