scholarly journals Analytical Investigation of the Flexural Capacity of Precast Concrete Frames with Hybrid Joints

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Ji-Hun Kim ◽  
Won-Kee Hong ◽  
Hee-Cheul Kim ◽  
Seong-Kyum Kim
Keyword(s):  
Precast Concrete ◽  
Limit State ◽  
Maximum Load ◽  
Analytical Investigation ◽  
Total Contribution ◽  
Moment Capacity ◽  
Composite Columns ◽  
Strain Compatibility ◽  
Load Limit ◽  
Hybrid Joints

This study aims to evaluate flexural strength based on the inelastic neutral axis calculated from all stress states of the proposed precast composite columns with hybrid beam-column joints, which facilitate the erection of concrete precast frames in a similar manner to that used for steel frames. It was also shown analytically that hybrid joints with headed studs contribute significantly to the flexural moment capacity and effectively increase the flexural structural performance of precast composite columns. The strain compatibility-based analytical results were compared with test data, showing results with an error of less than 8% at the critical section for the maximum load limit state of specimens. It is observed that the strength contributed by steel sections and headed studs increased by 30% and 35% at the yield limit state and maximum load limit, respectively, reducing the dependence on rebars. The total contribution of the headed studs was as large as 12.2% (average of the two layers of headed studs) at the maximum load limit state, whereas the strength provided by the tensile rebars decreased from 90.5% to 63.9% for the specimen with headed studs at the maximum load limit state.

scholarly journals Improving Efficiency, Extending the Maximum Load Limit and Characterizing the Control-Related Problems Associated With Higher Loads in a 6-Cylinder Heavy-Duty Natural Gas Engine

2010 ◽  
Author(s):  
Mehrzad Kaiadi ◽  
Per Tunestal ◽  
Bengt Johansson
Keyword(s):  
Natural Gas ◽  
Compression Ratio ◽  
Diesel Engines ◽  
Maximum Load ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Heavy Duty ◽  
Load Limit ◽  
Overall Efficiency ◽  
Exhaust Gas Temperature

High EGR rates combined with turbocharging has been identified as a promising way to increase the maximum load and efficiency of heavy duty spark ignition Natural Gas engines. With stoichiometric conditions a three way catalyst can be used which means that regulated emissions can be kept at very low levels. Most of the heavy duty NG engines are diesel engines which are converted for SI operation. These engine’s components are in common with the diesel-engine which put limits on higher exhaust gas temperature. The engines have lower maximum load level than the corresponding diesel engines. This is mainly due to the lower density of NG, lower compression ratio and limits on knocking and also high exhaust gas temperature. They also have lower efficiency due to mainly the lower compression ratio and the throttling losses. However performing some modifications on the engines such as redesigning the engine’s piston in a way to achieve higher compression ratio and more turbulence, modifying EGR system and optimizing the turbocharging system will result in improving the overall efficiency and the maximum load limit of the engine. This paper presents the detailed information about the engine modifications which result in improving the overall efficiency and extending the maximum load of the engine. Control-related problems associated with the higher loads are also identified and appropriate solutions are suggested.

Bearing Capacity of Structures Made of Materials with Different Tensile and Compression Strengths

2019 ◽  
Vol 968 ◽  
pp. 200-208
Author(s):  
Mykola Soroka
Keyword(s):  
Cross Section ◽  
Rectangular Cross Section ◽  
Limit State ◽  
Analytical Calculation ◽  
Bending Moment ◽  
Maximum Load ◽  
Longitudinal Force ◽  
Plastic State ◽  
Limiting State ◽  
Tension And Compression

The paper considers the problem of the ultimate load finding for structures made of a material with different limits of tensile strength and compression. The modulus of elasticity under tension and compression is the same. It is assumed that upon reaching the ultimate strength, the material is deformed indefinitely. The calculations use a simplified material deformation diagram — Prandtl diagrams. The limiting state of a solid rectangular section under the action of a longitudinal force and a bending moment is considered. The dependences describing the boundary of the strength of a rectangular cross section are obtained. Formulas allowing the calculation of the values of the limit forces and under the action of which the cross section passes into the plastic state are derived. Examples of the analytical calculation of the maximum load for the frame and two-hinged arch are given. An algorithm is proposed and a program for calculating arbitrary flat rod systems according to the limit state using the finite element method is compiled. The proposed algorithm does not involve the use of iterative processes, which leads to an exact calculation of the maximum load within the accepted assumptions.

Seismic Performance of In-Filled Steel-Concrete Composite Columns Using Fiber Analysis Method

2006 ◽  
Vol 326-328 ◽  
pp. 1821-1824 ◽  
Author(s):  
Jin Ho Kim ◽  
Tae Wook Kim
Keyword(s):  
Seismic Performance ◽  
Axial Loading ◽  
Steel Tube ◽  
Moment Capacity ◽  
Composite Columns ◽  
Fiber Analysis ◽  
Lateral Response ◽  
Analysis Technique ◽  
The Moment ◽  
Cft Column

The study for cyclic load-displacement relationship and seismic characteristics of square Concrete-Filled Steel Tubular (CFT) columns is experimentally and analytically conducted. Nine CFT column specimens are tested under constant axial loading and monotonically increasing lateral loading. For predicting the strength and ductility of CFT columns, fiber analysis technique is used. The analytical results show reasonable agreement with experiment results and the moment capacity of CFT columns is predicted with reasonable accuracy using the fiber model. The influence of the steel tube on the lateral response of CFT columns is studied for the evaluation of seismic performance.

Structural Integrity Assessment of Precast Concrete Slabs Employing Conventional and Recycled Coarse Aggregates via Vibration Tests

2014 ◽  
Vol 600 ◽  
pp. 504-513 ◽  
Author(s):  
Roberto Leal Pimentel ◽  
Sandro Marden Torres ◽  
Enildo Tales Ferreira ◽  
Aluísio Braz de Melo
Keyword(s):  
Structural Integrity ◽  
Load Capacity ◽  
Precast Concrete ◽  
Damping Ratio ◽  
Limit State ◽  
Load Level ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Impact Excitation ◽  
Integrity Assessment

Precast slabs were tested, consisting of ceramic blocks supported by concrete ribs and with a concrete topping a few centimeters thick. These structures are very common in Brazil, being employed for the construction of houses and small buildings. In one of the tested slabs, recycled coarse aggregate was employed while conventional aggregate (granite gravels and quartz sand) was employed in the other tested slab. This study is part of a broader experimental programme which was designed to assess the applicability of concrete containing recycled aggregates as conventional aggregate replacement. In order to get insight into the structural behavior of slabs with recycled aggregates, the main focus of this paper is to assess the effect of structural load level on vibration parameters (Resonance Frequency, Damping Ratio and Transit Time). Full scale slab structural integrity was assessed by following changes in these parameters via a vibration (modal) test employing impact excitation. The structures were tested for several static load ratios (load to ultimate loading ratios (55%, 82% and 98%)). Visual inspection of induced cracking was also performed. The results obtained indicate a reduction of stiffness in both slabs up to 50% of the stiffness of the respective uncracked structure, which followed a similar trend despite the aggregate types. As for the damping ratios, the recycled aggregate containing slab showed lower values in comparison to the control slab with conventional aggregate. Whereas the former results might indicate similar load capacity, the latter, in principle, may have implications for the vibration serviceability limit state of structures. However, although structures with lower damping ratio can potentially present vibration problems, these studied elements are not often subjected to excessive vibration in its service life.

scholarly journals Experimental and Computational Parametric Analysis of CFST and CFFT Columns

2019 ◽  
Vol 8 (6) ◽  
pp. 2701-2706
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Performance ◽  
Structural Parameters ◽  
Maximum Load ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Composite Columns ◽  
Reinforced Polymer ◽  
Pattern Maximum ◽  
Cfst Columns

‘Concrete Filled Steel Tubes (CFST)’/ ‘Concrete Filled FRP Tubes (CFFT)’ comprises of a steel/ ‘Fiber Reinforced Polymer (FRP)’ hollow pipe of circular or rectangular shape filled with plain or reinforced concrete. Need of such composite columns in the field of building construction is due to advancements in technology, need of bigger space in smaller land area, ease in construction workability, and a lot of other modern time requirements. This paper defines an experimental and computational project carried out by testing a total of 49 CFST columns and 60 CFFT columns. Three Finite Element models were also made using the software pack ABAQUS. Variables for the study were aspect ratio of columns, Shape of columns (i.e. square, circular or rectangular) and material (i.e. steel or FRP). Basic aim of the project was to find structural parameters like load-deflection behaviour, deflection pattern, maximum load carrying capacity etc. The Steel reinforced concrete-filled fiber reinforced polymer (FRP)tubular column is proposed as a new form of composite column to obtain higher mechanical performance. A comparative analysis was also carried out using three main resulting indices like Ductility Index (DI), Strength Index (SI) and Concrete Contribution Ratio (CCR). Comparative observations between CFST/CFFT columns of different shapes and sizes is carried out, also experimental results were compared with analytical results obtained from ABAQUS software.

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