• Structural Engineering and Mechanics
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• v.34 no.3
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• pp.301-317
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• 2010

This paper studies the reliability of an analytical tool for predicting the lateral load-deformation response of RC columns while subjected to lateral cyclic displacements and axial load. The analytical tool in this study is based on a fiber element model implemented into the program DRAIN-2DX (fiber element). The response of RC column under cyclic displacement is defined by the behavior of concrete, and reinforcing steel under general reversed-cyclic loading. A tri-linear stress-strain relationship for the cyclic behavior of steel is proposed and the improvement in the analytical results is studied. This study only considers the behavior of columns with flexural dominant mode of failure. It is concluded that with the implementation of appropriate constitutive material models, the described analytical tools can predict the response of the columns with reasonable accuracy when compared to experimental data.

• Journal of Ocean Engineering and Technology
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• v.18 no.6 s.61
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• pp.58-69
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• 2004

In order to investigate the characteristics of the lateral earth pressure at rest, under hysteretic $K_o-loading/unloading$ conditions, seven types of multi-cyclic models have been studied, using dry sand. For this study, the new type of $K_o-oedometer$ apparatus was developed, and the horizontal pressure was accurately measured. The multi-cyclic models consist of primarily 3 cases: (i) $K_o-test$ under the same loading / unloading condition, (ii) multi-cyclic loading / unloading $K_o-test$ exceeding the maximum pre-vertical stress, and (iii) multi-cyclic loading / unloading $K_o-test$ within the maximum pre-vertical stress. Results fromthe multi-cyclic model indicated that a single-cyclic model could be extended if the exponents for the unloading condition $(\alpha\;and\;\alpha^*)$ and the reloading coefficients $(m_r,\;and\;m_r^{\ast})$ were primarily dependent upon the type of model, number of cycles, and the relative density.

• Structural Engineering and Mechanics
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• v.50 no.4
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• pp.459-469
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• 2014

One of the most important structural components of steel structures is the column-base connections which are obliged to transfer horizontal and vertical loads safely to the reinforced concrete (RC) or concrete base. The column-base connections of steel or composite steel structures can be organized both moment resistant and non-moment resistant leading to different connection styles. Some of these connection styles are ordinary bolded systems, socket systems and embedded systems. The structures are frequently exposed to cycling lateral loading effects causing fatal damages on connections like columns-to-beams or columns-to-base. In this paper, connection of steel column with RC base was investigated analytically and experimentally. In the experiments, bolded connections, socket and embedded connection systems are taken into consideration by applying cyclic lateral loads. Performance curves for each connection were obtained according to experimental and analytical studies conducted and inelastic behavior of connections was evaluated accordingly. The cyclic lateral performance of the connection style of embedding the steel column into the reinforced concrete base and strengthening of steel column in upper level of base connection was found to be higher and effective than other connection systems. Also, all relevant test results were discussed.

• Geomechanics and Engineering
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• v.9 no.3
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• pp.313-328
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• 2015

In the present study, a CPT-based p-y analysis method was proposed for offshore mono-piles embedded in sands. Static and cyclic loading conditions were both taken into account for the proposed method. The continuous soil profiling capability of CPT was an important consideration for the proposed method, where detailed soil profile condition with depth can be readily incorporated into the analysis. The hyperbolic function was adopted to describe the non-linear p-y curves. For the proposed hyperbolic p-y relationship, the ultimate lateral soil resistance $p_u$ was given as a function of the cone resistance, which is directly introduced into the analysis as an input data. For cyclic loading condition, two different cyclic modification factors were considered and compared. Case examples were selected to check the validity of the proposed CPT-based method. Calculated lateral displacements and bending moments from the proposed method were in good agreement with measured results for lateral displacement and bending moment profiles. It was observed the accuracy of calculated results for the conventional approach was largely dependent on the selection of friction angle that is to be adopted into the analysis.

• Earthquakes and Structures
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• v.16 no.5
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• pp.533-546
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• 2019

This study presents an experimental investigation on six beam-column joint specimens under the lateral cyclic loading. The aim was to explore the effectiveness of steel fiber-reinforced concrete (SFRC) in reducing the transverse shear stirrups in beam-column joints of the reinforced concrete (RC) frames with strong-columns and weak-beams. Two RC and four SFRC specimens with different types of reinforcement detailing and steel fibers of volume fraction in the range of 0.75-1.5% were tested under gradually increasing cyclic displacements. The main parameters investigated were lateral load-resisting capacity, hysteresis response, energy dissipation capacity, stiffness degradation, viscous damping variation, and mode of failure. Test results showed that the diagonally bent configuration of beam longitudinal bars in the beam-column joints resulted in the shear failure at the joint region against the flexural failure of beams having straight bar configurations. However, all SFRC specimens exhibited similar lateral strength, energy dissipation potential and mode of failure even in the absence of transverse steel in the beam-column joints. Finally, a methodology has been proposed to compute the shear strength of SFRC beam-column joints under the lateral loading condition.

• Structural Engineering and Mechanics
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• v.66 no.3
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• pp.305-315
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• 2018

Interaction of lateral loading, combined with axial force needs to be determined with care in reinforced concrete (RC) one-dimensional structural members (1D SMs) such as beam-columns (BCs) and columns. RC 1D SMs under heavy axial loading are known to fail by brittle mode and small lateral displacements. In this paper, a macro element-based algorithm is proposed to analyze the RC 1D SMs under monotonic or cyclic combined loading. The 1D SMs are discretized into macro-elements (MEs) located between the critical sections and the inflection points. The critical sections are discretized into fixed rectangular finite elements (FRFE). The nonlinear behavior of confined and unconfined concretes and steel elements are considered in the proposed algorithm. The proposed algorithm has been validated by the results of experimental tests carried out on full-scale RC structural members. The evolution of ultimate strain at extreme compression fiber of a rectangular RC section for different orientations of lateral loading shows that the ultimate strain decreases with increasing the axial force. In the examined cases, this ultimate strain ranges from 0.0024 to 0.0038. Therefore, the 0.003 value given by ACI-318 code for ultimate strain, is not conservative and valid for the combined load cases with significant values of axial force (i.e. for the axial forces heavier than 70% of the ultimate axial force).

• Earthquakes and Structures
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• v.21 no.5
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• pp.445-460
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• 2021

This study experimentally explored the behaviour of 12 concrete filled steel tube (CFST) and steel tube columns subjected to lateral cyclic loading. The L/D ratio was 12.3 while D/t ratios were 45.4, 37.8 and 32.4, classifying these 12 specimens into 3 groups. Each group included 3 CFST and 1 steel tube columns and were tested to failure. The experimental results indicated that CFST specimens reached the state of 'collapse prevention' (drift 4%) prior to the occurrence of local buckling. Strength degradation of CFST specimens did not occur up to the failure by buckling. This showed the favourable characteristic of CFST columns in preventing collapse of structures subjected to earthquakes. The high energy absorption capability in the post collapse limit state was appropriate for dissipating energy in structures. Compared to steel tube columns, CFST columns delayed local buckling and prevented inward buckling. Consequently, CFST columns exhibited their outstanding seismic performance in terms of the increased ultimate resistance, capacity to sustain 2-3 additional load cycles and significantly higher drift. A simple and reasonably accurate model was proposed to predict the ultimate strength of CFST columns under lateral cyclic loading.

• Journal of the Korean Geotechnical Society
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• v.35 no.6
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• pp.39-48
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• 2019

This study investigated the lateral behavior of monopile embedded in the dry sand through cyclic lateral loading test using a centrifuge test. The sand sample for the experiment was the dry Jumunjin standard sand at 80% relative density and the friction angle of $38^{\circ}$. In the experimental procedure, firstly, it was determined the static lateral bearing capacity by performing the static lateral loading test to decide the cyclic load. This derived static lateral bearing capacity values of 30%, 50%, 80%, 120% were determined as the cyclic lateral load, and the number of cycle was performed 100 times. Through the results, the experiment cyclic p-y curve was calculated, and the cyclic p-y backbone curve by depth was derived using the derived maximum soil resistance point by the load. The initial slope at the same depth was underestimated than API (1987) p-y curves, and the ultimate soil resistance was overestimated than API (1987) p-y curves. In addition, the result of the comparison with the suggested dynamic p-y curve was that the suggested dynamic p-y curve was overestimated than the cyclic p-y backbone curve on the initial slope and soil resistance at the same depth. It is considered that the p-y curve should be applied differently depending on the loading conditions of the pile.

• Steel and Composite Structures
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• v.1 no.2
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• pp.201-212
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• 2001

In order to investigate the effect of the loading rate on the mechanical behavior of SRC shearwalls, we conducted the lateral loading tests on the 1/3 scale model shearwalls whose edge columns were reinforced by H-shaped steel. The specimens were subjected to the reversed cyclic lateral load under a variable axial load. The two types of loading rate, 0.01 cm/sec for the static loading and 1 cm/sec for the dynamic loading were adopted. The failure mode in all specimens was the sliding shear of the in-filled wall panel. The edge columns did not fail in shear. The initial lateral stiffness and lateral load carrying capacity of the shearwalls subjected to the dynamic loading were about 10% larger than those subjected to the static loading. The effects of the arrangement of the H-shaped steel on the lateral load carrying capacity and the lateral load-displacement hysteresis response were not significant.

• Computers and Concrete
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• v.13 no.3
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• pp.377-387
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• 2014

This paper presents an experimental study on socket base connections of precast reinforced concrete columns. The main purpose of this study is to determine socket base connection which has the closest behavior to monolithic casted column-base joints. For this purpose, six specimens having different column-socket base connection details were tested under cyclic loading. For each test, strength, stiffness, ductility and drift ratios of the specimens were determined. Test results indicated that a suggested connection type is 10%-30% stronger than the other type of connections under lateral loading. The welded connection (PC-5) had better lateral load carrying capacity and ductility. On the other hand, performance of standard connection (PC-1) which is commonly used in construction was weaker than other connections. Thus, decision of connection type should be referred not only performance but also applicability.