Optimal Selection of High-Performance Concrete for Post-Tensioned Girder Bridge Using Advanced Hybrid MCDA Method

The selection of material solutions is a basic decision-making problem that occurs in engineering issues. It affects the entire life cycle of a building structure, its safe use, maintenance costs, and a need to meet requirements for sustainable development, including recycling. This paper aims at selection of the optimum composition of HPC designed for monolithic girder structures of post-tension bridges. For the analysis, a set of 12 new-generation concretes (HPC) was designed, made, and tested. A full-scope set of evaluation criteria was created and then the optimal alternative was selected. For this purpose, an advanced hybrid algorithm combining EA FAHP (Extent Analysis Fuzzy Analytic Hierarchy Process) and FuzzyTOPSIS (Fuzzy Technique for Order Preference by Similarity to an Ideal Solution) methods was used. The obtained results indicate a possibility for the practical application of the proposed algorithm by decision-making engineering staff. It can also be the basis for further research on application compared to other material and design solutions and, depending on the issue, different combination of aggregated methods.

Study and Analysis of Post Tension Flat Slab for Different Tendon Layouts

The main purpose of this paper is to study of post tension flat slab and study of their various tendon profiles. In this paper the analysis of various different tendon layouts with different sizes is done. In this paper different sizes of slab is considered and analysis is done with the help of SAFE software. With help of analysis we know the deflection of PT slab for different layouts. In this paper tendon layouts are as banded tendons in main direction, banded tendons in both directions, distributed tendons in both directions, banded and distributed tendons in both directions are considered with different sizes. This paper also includes PT strip stress diagram and layouts.

EVALUATION OF POST TENSIONED SLAB AND ITS CONTRAST WITH TRADITIONAL RCC SLAB: REVIEW

Post-tensioning is a technique for reinforcing concrete slabs with high-strength tendons. Tendons retain much more concrete in compression. Posttension floors are capable of bearing almost every dead load due to their tensioned tendons, which aid to perform live loads acts on slabs & make them stronger than traditional slabs. For commercial and residential floors, PT slabs are suggested for comparatively limited depths, less heavy weights and free floor elevation. The research on the R.C.C and PT slab has been reviewed, with an integrative impact with the lateral load. The primary aim of this, is to review the reaction and behavioural characteristics of the post-tension flat plate during an earthquake and to contrast it with the traditional slab. For this purpose, the past papers related to the PT slab were studied and a successful conclusion has been made.

Efficiency of Vierendeel Girder, Post-tensioned Girders and Steel Beams for Long Cantilevers in Buildings

Cantilevers are a part of our life, they are everywhere: bridg–es, building’s balconies, traffic signs, car parking shades even the aircraft’s wings. The long cantilevers of the buildings always present as a big challenge to structural engineers in their practice life. The structural behavior of these cantilevers depends on a several factors, such as rigidity of the slab, rigidity of columns or walls, span continuity... etc. But the real dilemma lies in the economical choice. This paper focused on the cantilever’s structural analysis according to the used structural. Moreover, it shows a comparison between three structural system choices: Vierendeel Girder, Post - Tensioned Girders and Steel Composite Beam in a graph. The objective of this paper is to give a guideline to the structural engineers to choose the optimum system of the building cantilevers according to the factors mentioned earlier. At the end, the paper illustrated the Vierendeel girder is the most efficient system for cantilevers. Accordingly, recommendations result on that up to 4.0 m cantilever length steel beams will be enough, for more than 4.0 and less than or equal to 6.0 m post-tension is recommended, and for more than 6.0 m cantilever we should use Vierendeel girder.

Experimental study on transverse stress of different forms of concrete bridge deck

<p>Steel plate composite bridge is one of the most widely used form of bridges. With the application of pre- stressed concrete, the improvement of thick steel plate quality and welding technology, steel plate composite bridge with less main girder has been widely used in engineering. To compare the mechanical properties of twin-girder and multi-girder steel plate bridge, two full-scale concrete bridge deck specimens are manufactured and tested. The stress and deformation of the structural members of the two specimens are tested, the development of concrete cracks is recorded in detail, and the ultimate bearing capacity and failure form are obtained. The test results show that the concrete slab in the form of twin-girder with post- tension will not crack under the normal vehicle load, while multi-girder one will crack, and the maximum crack width is 0.02 mm. The ultimate bearing capacity of twin-girder is 622 kN and the multi-girder is 850 kN. The failure mode of twin-girder is tension failure, and multi-girder is compression failure.</p>

Seismic Strengthening of Low Strength Concrete Columns using High Ductile Metal Strap Confinement: A Case Study of Kindergarten School in Northern Thailand

The 2014 Chaing Rai earthquake (Thailand) caused extensive damage in many reinforced concrete (RC) buildings built before the introduction of modern seismic design guidelines. Much of the damage on these buildings was attributed to the inadequate capacity and/or ductility of columns. As a result, suitable and cost-effective strengthening techniques for such substandard elements are necessary. This article presents a case study on the seismic strengthening of a one-story RC kindergarten school located in Ampor Pan, Chaing Rai province. The building was partially damaged during the afore-mentioned earthquake, which led to cracking in walls, columns, and beam-column joints. As part of the initial assessment, innovative repair solutions were sought to minimize construction time, labor, and material cost. Accordingly, an innovative strengthening technique that uses Post-tension Metal Strapping (PTMS) was proposed to strengthen the damaged RC elements. This article presents details of the structural assessment performed on the building, as well as details of the PTMS strengthening strategy, which was applied for the first time in a real full-scale structure. This article contributes towards the validation and application of the PTMS strengthening on real structures, which had not been possible until now.

A Review on Reinforced Concrete Beam Column Joint: Role, Modeling and Recent Details

Reinforced concrete frames are commonly used systems in buildings. The philosophy behind the proper design for this type of frames is to provide them with sufficient ductility. The structural ductility of a frame is mainly determined by the ductility of its components, i.e., the beams, columns, and joints forming this frame. Beam-column joint role in a building is to connect its components together and enable these components to reach their ultimate resistance. Its stiffness, strength, and ductility are key characteristics needed to guarantee efficient building behaviour under the action of different loads. Previous research attributed some building’s damage to inadequate reinforcement details of its joints. Deficiency in joints performance is related to inadequate codes guidelines or to bad construction practice. This paper reviewed the provisions of three different codes (ACI 318-08, Eurocode 8, and ECP-203) concerning the proper design and detailing of different joints. This review study aims to introduce a wider overview on the assessment of joints performance in buildings under different loading scenarios. This data base will enable practicing engineers to identify the joint key parameters with providing different analytical procedures. This study investigates joints in different configurations. These include planner joints, joints with transverse beams, and the common joint situation with the presence of both transverse beams and slab. This survey includes experimental and analytical representation of the previous mentioned joints. Different retrofitting schemes are presented as well for every considered joint. This review allows to identify the evolution of joints capacity in function of reinforcement detailing, level of axial stresses, and loading history. The analysis shows that a decrease in joint resistance can be recovered by using i) haunches brackets, ii) FRP, or iii) post tension metal strip.