Evaluation of internal blast resistance of bi-directionally prestressed concrete tubular structure according to ANFO explosive charge weight

When extreme loading from an internal is applied to prestressed concrete (PSC) structures, serious property damage and human casualties may occur. However, existing designs for PSC structures such as prestressed concrete containment vessels (PCCV) do not include features to protect the structure from the blasts. Therefore, the internal blast resistance capacity of PSC structures is evaluated by internal blast tests on bi-directional PSC tubular members. The goal of the study was to obtain the structural behavior data from an internal detonation. The ANFO charges were detonated at the center of the mid-span of the tube specimen with a standoff distance of 1,000 mm. The data acquired included blast pressure, deflection, strain, crack pattern, and prestressing loss. The data are used derive the equations to calculate the required internal blast charge weight to fail a real-scale PCCV and to calibrate a commercial simulation program to be used for internal blast simulations.

An Innovative Smart Concrete Anchorage with Self-Stress Sensing Capacity of Prestressing Stress of PS Tendon

An innovative smart concrete anchorage (SCA) has been developed for monitoring the stress of prestressing (PS) tendons by utilizing smart ultra-high-performance concrete (UHPC). The smart UHPC contained 2 vol% steel fibers and fine steel slag aggregates instead of silica sands. The effects of different electrode materials, arrangements, and connectors on the self-stress sensing capacity of the SCA are discussed. A prototype SCA demonstrated its feasibility and sufficient self-stress sensing capacity to be used in monitoring the prestressing loss of the PS tendon. As the tensile stress of the PS tendon increased from 0 to 1488 MPa, the fractional change in resistivity (FCR) of the prototype SCA, with horizontally paired copper wire electrodes and a plug-in type connector, decreased linearly from 0% to −1.53%, whereas the FCR increased linearly from −1.53% to −0.04% as the tensile stress of the PS tendon decreased from 1488 to 331 MPa.

TINJAUAN PERENCANAAN GELAGAR BETON PRATEGANG PADA JEMBATAN BAKONGAN KECAMATAN PERMATA KABUPATEN BENAR MERIAH

Bakongan bridge located in Bakongan village, Permata Subdistrict, Bener Meriah District. Based on the characteristics of the river, the bridge isplanned to Bakongan spans 13,6 meters long and 6 meters width. Girder longitudinal direction planned for the bridge is prestressed concrete girder type of post­ tension with the imposition of standard rules RSNI T-02-2005, RSNI T-12-2004 and Construction Manual 021/BM/201 J . Jn the early stages of planning done preliminary design to determine the dimensions of the main bridge, the calculation of the secondary structure are used as load analysis that occurs, the control voltage that occurs in the structure, post-tensile prestressing loss, sectional capacity, control deflection, and depiction. Quality of concrete used was Jc = 45 MPa, tendon used is seven strand wire with a diameter of 9,3 mm inch diameter 51 mm shells tendon. Voltage tendonfpu = 1860 MPa, quality threaded steel reinforcement isfY = 320 MPa, and quality plain steel reinforcement isfY = 240 MPa. Moments that occur in the calculation of girder 1502,0967 KNM combination III. Number of tendons obtained from the calculation is 5 to 35 pieces offruit on each strand tendons. Total loss of prestressing force obtained at 817,54 MPa or 34 %. Principal reinforcement used Æ13 mm, Æ10-shear reinforcement used in the staging area 100 mm and g 10-600 mm in thefield area. Ultimate moment capacity of prestressed beams 3629664KN/m combination Ill of calculation. Greatest deflection is 0.0151 meters caused by a combination JV. Keywords: Concrete prestressed, Post-tension girder, tendons, reinforcement

Estimation Method for Prestress Loss of Externally Prestressed Composite Girder Bridges

To accurately calculate the prestress of externally prestressed composite girder bridges, the six critical factors (the prestressing tendon withdrawal and anchor deformation, friction between prestressing tendon and deviator, prestressing tendon relaxation, concrete creep, concrete shrinkage and temperature changes) that cause the prestress loss of such type of the bridges are summarized and the corresponding simplified calculation methods are respectively derived on the basis of the existing researches. The prestressing tendons ability has an important influence on the mechanical behavior of prestressed composite girder bridges, which is the key design parameters. Prestress loss will occur in the process of long-term use, so that the whole beam stress redistribution occurs. How to accurately calculate the value of the prestressing loss is an issue of great concern to engineers. And at present there is few research for prestressed composite girder bridges. On the basis of existing research, this paper summarizes the key factors that lead to loss of prestress and derives the corresponding simplified calculation method for design reference.