Evaluation Of Ultimate Strength Research Articles

Evaluation of Ultimate Strength of Reinforced Concrete Beams Strengthened with FRP Sheets under Torsion

The ultimate torque of reinforced concrete (RC) members strengthened with fiber reinforced polymer (FRP) sheets does not only depend on the torque of RC members, but also on the FRP contribution to the torque. For structural design, predicting the accurate torsional capacity of the strengthened beams is considerably important. Three existing models for calculating the ultimate torsional moment of RC beams and two existing models for computing the FRP contribution to the ultimate torque are described and combined. Based on an experimental database collected from existing literature, six combinations were discussed and evaluated from the calculative values compared with the experimental results. The comparison shows that the combination of ACI 318 and fib Bulletin 14 models (Group 2), as well as Chinese and Ghobarah models (Group 6), can reasonably and accurately predict the ultimate torque of beams strengthened with FRP sheet. Furthermore, the ultimate torque of six boxsection beams strengthened with fully wrapping or U-wrap calculated by the Group 6 shows closely to the experimental results.

モルタル充填接合工法による杭頭接合部の開発に伴う耐力評価法の検討

A new steel column and ready-made pile joint system is proposed by the authors. This new joint system has been using mortal in-filled steel tube joint. These abilities can enable to reduce costs and construction period by omitting mold construction work, rebar construction, and concrete work for building the foundation.In a structural design according to the present joint system, evaluation method of ultimate strength for mortar-filled joints should be clear. Therefore, in this paper, ultimate strength evaluation method in the case of the development of pile head joint by mortal in-filled method is clarified obtained by the present experiments.

Nonlinear Dynamic Response and Structural Evaluation of Container Ship in Large Freak Waves

Many ship accidents and casualties are caused by large freak ocean waves. Traditionally, the strength of ships against freak waves is assessed by means of ultimate strength evaluation, assuming quasi-static conditions, but the nonlinear dynamic structural response of ships to freak waves should be considered as well. This paper describes how the strength of a ship can be evaluated in terms of its nonlinear vertical bending moment (VBM). Linear dynamic VBM of a ship, which is derived from hydrodynamics, is calculated using a time-domain strip theory code under freak wave conditions, and the nonlinear dynamic VBM, which is dependent on structural nonlinearity, is calculated using a combination of quasi-static and dynamic nonlinear analyses based on the finite element method (FEM). The nonlinear and linear VBMs are then compared to assess how they differ. Then, the influence of freak wave height and wave speed on the VBMs and deformation is studied.

Evaluation of ultimate strength of stiffened panels under longitudinal thrust

A series of collapse analyses is performed applying nonlinear FEM on stiffened panels subjected to longitudinal thrust. MSC.Marc is used. Numbers, types and sizes of stiffeners are varied and so slenderness ratio as well as aspect ratio of local panels partitioned by stiffeners keeping the spacing between adjacent longitudinal stiffeners the same. Initial deflection of a thin-horse mode is imposed on local panels and that of flexural buckling and tripping modes on stiffeners to represent actual initial deflection in stiffened panels in ship structures. On the basis of the calculated results, buckling/plastic collapse behaviour of stiffened panels under longitudinal thrust is investigated. The calculated ultimate strength are compared with those obtained by applying several existing methods such as CSR for bulk carriers and PULS. Simple formulas for stiffened panels, of which collapse is dominated fundamentally by the collapse of local panels between longitudinal stiffeners, are also examined if they accurately estimate the ultimate strength. Through comparison of the estimated results with the FEM results, it has been concluded that PULS and modified FYH formulas fundamentally give good estimation of the ultimate strength of stiffened panels under longitudinal thrust.

Correlation of thermally induced acoustic emission and ultimate compression strength in hard rocks

The authors have experimentally established and substantiated the relation between the ultimate compression strength and the low-temperature induced acoustic emission in the compressed hard rock specimens, averaged in a preset temparature range. This relation shows itself most clearly if data sampling is subjected to pre-censoring by withdrawal of data obtained on specimens with abormal defectiveness detected from the analysis of the thermally induced acoustic emission. The study case of the ultimate strength evaluation for Kapustinsky granite by using the thermoacoustic emission measurements is reported.

An Indeterminate Strut-Tie Model and Load Distribution Ratio for RC Deep Beams - (I) Model & Load Distribution Ratio

The ultimate strength of simply supported reinforced concrete deep beams is governed by the capacity of the shear resistance mechanism. The structural behavior of the deep beams is controlled mainly by the mechanical relationships between the primary design variables including shear span-to-effective depth ratio, flexural reinforcement ratio, and the compressive strength of concrete. In this study, a simple indeterminate strut-tie model which reflects all characteristics of the ultimate strength and behavior of the deep beams was presented. A load distribution ratio, defined as the fraction of load transferred by a truss mechanism, was also proposed to help structural designers perform the rational design of deep beams by using the strut-tie model approaches of current design codes. In the determination of the load distribution ratio, a concept of balanced shear reinforcement ratio which ensures the ductile shear design of the deep beams was introduced, and the effect of the primary design variables was reflected through numerous numerical analyses of the presented indeterminate strut-tie model. In the companion paper, the validity of the presented model and load distribution ratio was examined by applying them to the evaluation of ultimate strength of 234 simply supported reinforced concrete deep beams tested to failure.

Evaluation of Ultimate Strength of Longitudinally and Transversely Profiled Steel Plate

Evaluation of Ultimate Strength of Longitudinally and Transversely Profiled Steel Plate

STRENGTH EVALUATION OF JOINT S MEMBER WITH REINFORCED CONCRETE MEMBER USING ANCHOR BOLT

The purpose of this study is to clarify stress transferring mechanism and strength evaluation of the joint connected steel member with reinforced concrete member using anchor bolt based on stress transfer from steel member and reinforced concrete member. To clarify stress transferring mechanism of the joint connected steel member with reinforced concrete member using anchor bolt, seven T-shaped assemblages were tested under monotonic loading. From the test results, it was shown that stress transfer from steel member to reinforced concrete member in the joint could be mobilized by transverse reinforcements arranged intensively around anchor bolt. Based on the arch mechanism and the truss mechanism, a method capable of estimating the ultimate strength of the joint was proposed. The predictions were shown to be in good agreement with the test results. In addition, it was shown that this proposed strength model could apply to the ultimate strength evaluation of the exterior beam-column joint using mechanical anchorages on the reinforced concrete structure.

Damage simulator를 이용한 선박의 손상강도에 관한 연구

A damage analysis simulator, which is applicable for evaluating the residual strength of damaged ship, was developed in this paper. For this process, CDM (Continuum Damage Mechanics) approach has been implemented to the simulator by virtue of the numerical technique for evaluation of crack initiation and/or enlargement. A damage calculation program has been linked with a commercial finite element analysis code (NASTRAN) and a ultimate strength evaluation program (LSAP) in order to assess residual strength of damaged ship. As a results of series calculation for the frigate model, giving the quantitative structural damage to the ultimate strength evaluation, a residual strength with damage is predicted to be at least 70 percentage lower than the case of intact condition. It was found that the proposed technique can be used as a design support tool in the field of simulation based ship design.

Application of artificial neural networks to evaluation of ultimate strength of steel panels

Structural design of ships and offshore structures has been moving towards limit state design or reliability-based design. Improving the accuracy and efficiency of predicting the ultimate strength of structural components, such as unstiffened panels and stiffened panels, has a significant impact on our daily structural design. Empirical formulations have been widely used because of their simplicity and reasonable accuracy. In the past, empirical formulations were generally developed by using regression analysis. The model uncertainties of good empirical formulations are around 10%–15% in terms of coefficients of variation. In this paper, artificial neural networks (ANN) methodology is applied to predict the ultimate strength of unstiffened plates under uni-axial compression. The proposed ANN models are trained and cross-validated using the existing experimental data. Different ways to construct ANN models are also explored. It is found that ANN models can produce a more accurate prediction of the ultimate strength of panels than the existing empirical formulae. The ANN model with five (original) input variables has slightly better accuracy than the model with three input variables. This demonstrates the capacity of the ANN method to establish successfully a functional relationship between input and output parameters.

Evaluation of Ultimate Strength of Post-Tensioned Anchorage Zones

The anchorage zones of post-tensioned concrete members can be divided into local and general zones. The present study estimated the ultimate strengths of post-tensioned beams tested to anchorage failure using the AASHTO LRFD approximate stress analysis/design method, the critical section concept in which the strengths of the node-strut interface and local zone-general zone interface are examined, the bearing strength equation which considers the confinement effect due to reinforcing bars, and the nonlinear strut-tie model approach which incorporates nonlinear techniques in the selection, analysis, and verification processes of a strut-tie model, thereby evaluating their respective validity in the analysis and design of post-tensioned anchorage zones. The ultimate strengths of the post-tensioned beams in the nonlinear strut-tie model approach were estimated by checking the occurrence of a nodal zone failure mechanism, the structural instability of the selected strut-tie model due to the strength reduction of the struts and ties during the incremental loading steps, and conformity to the strut-tie model's geometric compatibility condition.

Behaviour and design of horizontally curved steel beams

This paper investigates the behaviour of I-beams curved in plan, and a proposed design method to estimate the ultimate strength of such beams subjected to gravity loading. First, a finite element method for analysing inelastic large-displacement behaviour of a horizontally curved I-beam is presented. The load—displacement and ultimate strength results generated by the finite element method are compared with the theoretical and experimental results published in the literature. The accuracy of the finite element analysis approach is thus established. An investigation is then followed to study the effects of residual stresses and radius of curvature-to-span length ratios on the ultimate strength behaviour of horizontally curved I-beams. An approximate equation is derived and proposed to evaluate the ultimate moment capacity of curved I-beams for several loading and boundary conditions. Based on the derived equation, standard charts are generated for the evaluation of ultimate strength of I-beams with different horizontal curvatures and span-lengths. Behaviour of curved beams with intermediate restraints is also studied both experimentally and analytically.

Strength of Composite Laminate with Reinforced Hole

Tension and compression tests of quasi-isotropic [0/ ± 45/90]2 s, graphite/epoxy lami nates containing a circular hole with reinforcement were conducted. Two types of rein forcement were investigated; adhesively bonded plug reinforcement or snug-fit unbonded plug in the hole. For each case of reinforcement, four different sizes of hole diameter and three types of reinforcing material (aluminum, plexiglass, steel) were employed for in vestigation. The experiments were mainly focused on the evaluation of ultimate strength of laminate with reinforced hole in comparison to its counterpart with the open hole.

An analytical evaluation of ultimate strength of beams based on linearized finite displacement theory

An analytical evaluation of the ultimate strength of singly symmetric beams subject to combined bending and compression is presented based on the linearized finite displacement theory of thin-walled members. An explicit cubic equation is obtained by the use of the initial yield criterion to determine the ultimate strength of laterally unsupported beams. The solutions correspond to the well-known Perry-Robertson type formula for the in-plane beam-column problems. Illustrative examples are given for demonstration. FEM solutions are also given to extend this concept for more general problem presentations.