Ultimate Lateral Load Research Articles

Nonlinear Static Pushover Analysis of Cold-Formed Steel Storage Rack Structures

ABSTRACT Individual components of cold-formed storage rack system are most vulnerable to local and torsional buckling under gravity as well as lateral loads.The capacity-based design of cold-formed storage rack system consists of deterministic allocation of strength and ductility in the structural elements and performance evaluation by suitable techniques. Nonlinear time history analysis (NTHA) and nonlinear static pushover analysis (NSPA) are most commonly followed techniques for seismic performance evaluation of any structural systems. Although, NTHA is the most accurate method of seismic demand prediction and performance evaluation, it is computationally heavy and even requires the selection and employment of an appropriate set of ground motions. This paper deals with analytical investigation of efficient configuration of conventional pallet racking system on the basis of seismic performance by using NSPA. This analytical study on conventional pallet racking system subjected to lateral loads is focused: i) to identify the local buckling failure modes of components of storage rack systems, ii) to evaluate the effect of local buckling on ultimate lateral load carrying capacity, and iii) to propose structural alterations for components of rack system so as to obtain most efficient configuration of conventional pallet racking system. Two different configurations of conventional pallet racking system are modeled and analyzed on the general purpose FE platform under monotonic unidirectional lateral loads. The results of NSPA show that pallet racking system with horizontal and inclined bracing is more efficient as evidenced from good estimates of the overall displacement, base shear and yielding capacities.

Factors Influencing the Behaviour of Flexible Pile Groups Under Lateral Loading in Soft Clay

Experimental investigation is carried out to study the lateral load–deflection and bending behaviour of model flexible pile groups embedded in soft clay. The effects of embedment length of pile, magnitude of applied lateral load, size of group, row and column wise position of piles in the group, cyclic loading and presence of vertical loading on lateral response of pile group are evaluated. Results from the tests reveal that flexible piles subjected to lateral load greater than about 60 % of ultimate lateral load cannot be considered as flexible. Maximum bending moment of front row pile of 3 × 3 group is about 16 % higher than that of middle row pile. Within the same row piles, corner pile has about 10 % higher bending moment than that of middle pile. Maximum bending moment in pile subjected to 15 cycles of loading is about 80 % higher than that for static loading. The lateral capacity of the 3 × 3 pile group with 60 % of ultimate vertical load is about 18 % less than that of the pile group with no vertical load.

Shear Behavior of Joint The Partial Prestressed Concrete Beam-Column Reinforced Concrete of Ductile Frame Structure Building In a Scure Residents and for Settlement Environment

Concentration of this study is to create a Specimens model of Joint Interior Beam - Column using Partial Prestressed Concrete Beams elements connected with Reinforced Concrete Column. Design capacity of Beam- Column Joint Shear is the horizontal shear reinforcement in the form of stirrups AE 10-50 mm to fill the empty space bj = 288 mm . The capacity Shear that can be deployed by the cross bar = 103.62 kN. Total shear force that is capable of detained by the beam-column joint structures are Vjh = 409 kN. This study is a continuation of research SRPMK models shaped beam - column joint with beam section 250/400 mm , and the column section 400/400 mm , the source of funds from Research Ditlitabmas Decentralization Program of Higher Education , through ITS Featured Research Grant in 2013 . Experimental studies have been conducted with Cyclic loading ( pseudo dynamic ) lateral , static axial load on the column as a stabilizer . Specimens ability to withstand Ultimate Lateral Cyclic Load : conditions Load push (press) = 470.90 kN and Load Pull = 465.80 kN. Everything is > 409 kN. Ductility structure also qualified in 3.50% Drift Ratio: Conditions Press m = 1.27 > 1.20, Pull Conditions m = 1.29 > 1.20. In general, behavioral modeling structure has qualified as a reliable protection occupancy when the building was hit by an earthquake.

Response of Single and Grouped Pile Subjected to Lateral Load in Cohesionless Soil

Piles are generally required to transfer load from a superstructure through weak or compressible strata, or through water, on to stiffer and less compressible soils and rock. The pile behavior is very important in Soil-Pile interaction (as known Kinematic Interaction) so that grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. In this research presents a series of experimental investigations carried out on single and group pile subjected to monotonic lateral loadings. The aluminum model piles were tested in the different relative densities in Johor Bahru sand. The sand samples were prepared by using the newly designed Mobile Pluviator adopted the air pluviation method. The different configurations of model pile groups for embedded length-to-diameter ratio equal to 32 into loose and dense sand spacing from 3 to 6 pile diameter (D) were conducted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. A ratio of s/D more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.

사질토 지반에서 수평하중에 따른 단일강관말뚝의 거동특성에 관한 실험적 연구

해상풍력기초를 설계함에 있어 사용하중에 대해 극한적인 조건뿐만 아니라 지속적인 동적하중에 대해 기초의 거동을 정확하게 파악하여 안정적이고 경제적인 기초를 개발할 필요성이 있다. 이를 위하여 강관말뚝을 일정비율로 축소시켜 모형말뚝을 제작하고, 모형토조에 모래층을 500mm의 높이로 포설한 후 모형말뚝을 모델링하여 정적 및 반복 수평재하실험을 실시하였다. 그 결과, 정적수평재하시 모형말뚝의 길이/직경(L/D)이 클수록 하중에 따른 변위는 증가하는 반면, 반복수평재하시 하중재하 횟수가 증가할수록 반복수평하중 1회당 발생하는 말뚝의 수평변위는 감소하였고 지반이 조밀할수록 반복수평하중에 의한 말뚝의 극한수평지지력의 증가율이 작아지는 것으로 나타났다. 또한 휨모멘트의 분포형상은 지반의 상대밀도에 상관없이 유사한 형태를 보였으며, 최대휨모멘트는 지표면으로부터 170mm지점에서 발생하는 것으로 나타났다. 그리고 지반의 상대밀도가 증가할수록 정적수평재하와 반복수평재하 조건에서 발생하는 최대휨모멘트는 증가했다. In order to fulfill the needs of reliable and economically feasible foundation, engineers should consider not only the working load that can endure extreme conditions but also apprehending precise behavior of continuous dynamic load while designing the foundation of offshore wind power generators. To actualize the foundation, a model pile was made in miniature. Also, calibration chamber was made and a 500mm height of sand-bed was made to perform "static lateral load experiment" and "repetitive loading experiment", total of two Lateral load tests. As a result, in Static Lateral load test, the bigger length/diameter of model pile led an increase in load displacement. However, when performing "Cyclic Lateral load test", the increase in number of under loading led the decrease in horizontal displacement from each repeated lateral load. While performing Static Lateral load test and repeated loading experiment, we could observe the decreasing in the rate of ultimate lateral load capacity increase of the pile. Also, it turned out that the higher relative density of the ground, the lower ultimate lateral load capacity by repeated horizontal loading.

Estimation of the maximum credible hazard in Kuala Lumpur and Singapore due to gigantic Sumatran megathrust earthquakes: based on a comparative study on attenuation laws

This paper has classified nine attenuation laws derived for subduction interface earthquakes through a comparative study based on the peak ground accelerations (PGAs) recorded in Peninsular Malaysia and Singapore. The goal of classification was to identify the attenuation laws that were the most compatible with the region. The PGAs predicted by the relations provided by Nabilah and Balendra (Earthq Eng 16:1076–1094, 2012) and Zhao et al. (Bull Seismol Soc Am 96:898–913, 2006) were found to correlate well with the recorded PGAs. The maximum credible hazard in Kuala Lumpur and Singapore was obtained by calculating the acceleration response spectra caused by three great Sumatran megathrust earthquakes (the worst possible earthquake scenarios) using Zhao et al. spectral attenuation law. Current building code in the region requires that buildings should be capable of resisting a notional ultimate lateral design load equals to 1.5 % of the characteristic dead weight, simultaneously applied at each floor (i.e., the minimum design level of buildings equals to ~0.15 m/s2). The results show that the risk level for structures of the two cities with natural period Tn = 1–1.5 s corresponding to 10- and 15-story buildings located on hard soil sites [National Earthquake Hazards Reduction Program (NEHRP) site class C] is high as the demand spectrum due to a worst possible earthquake scenario with moment magnitude (MW) 9.5 and an epicentral distance (Repi) of 600 km from Singapore was noticeably higher than their design level. The results of the present study are applicable in seismic hazard assessment projects in Peninsular Malaysia and Singapore. The most interesting conclusion from the earthquake engineering perspective, however, is that the design spectral shapes specified in IBC 2012 and Eurocode 8 (type 2) codes may not be particularly appropriate for sites that could be affected by large-magnitude, distant earthquakes.

유사동적실험에 의한 RCSF 외부접합공법으로 내진보강 된 중·저층 철근콘크리트 건물의 내진성능 평가

본 연구에서는 기존 강도증진형 내진보강법의 단점을 보완 개선할 수 있는 새로운 개념의 내진보강법인 RCSF (Reinforced Concrete Steel Frame) 외부접합형 내진보강공법을 제안하였다. RCSF 보강법은 거주자가 거주가 가능하면서 내진보강 공사를 실시할 수가 있으며, 접합부 시공성이 탁월하며, 특히 필요 내진보강량 산정이 간편한 전형적인 강도증진형으로 전단파괴가 지배적인 비내진상세를 가지는 국내 중 저층 철근콘크리트 건물에는 내력확보가 용이한 내진보강공법이다. 본 연구에서 제안한 RCSF 외부접합형 공법의 유용성을 검증 할 목적으로 기존 중 저층 철근콘크리트 학교건물의 골조를 대상으로 유사동적실험을 실시하여 검증함과 동시에 내진보강효과를 검토하였다. 그 결과, 국내에서 발생 가능한 최대 지진규모 (300gal)에서 비보강 골조는 붕괴를 하였지만, RCSF 외부접합형 내진보강법으로 보강한 골조는 경미한 지진피해가 예상되었으며, 대규모 지진 (400, 500gal)을 상정한 경우에도 소규모 이하의 지진피해가 예상되어 본 연구에서 개발한 RCSF 내진보강법의 유효성이 검증되었다고 사료된다. In this study, a new RCSF (Reinforced Concrete Steel Frame) external connection method is proposed for seismic strengthening of medium-and low-rise reinforced concrete buildings. The RCSF method, proposed in this study, is capable of carrying out the seismic retrofitting construction while residents can live inside structures. The method is one of the strength design approach by retrofit which can easily increase the ultimate lateral load capacity of concrete buildings controlled by shear. The pseudo-dynamic test, designed using a existing school building in Korea, was carried out in order to verify the seismic strengthening effects of the proposed method in terms of the maximum load carrying capacity and ductility. Test results revealed that the proposed RCSF strengthening method installed in RC frame enhanced conspicuously the strength and displacement capacities, and the method can resist markedly under the large scaled earthquake intensity level.

Numerical Analysis on Square CFT Stub Columns with Binding Bars under Cyclic Loading Based on OpenSEES

In order to study the seismic behavior of square concrete-filled steel tubular (CFT) columns with binding bars under cyclic lateral load, numerical simulation is carried out based on the finite element software OpenSEES. The influence factors of seismic performance on square CFT columns with binding bars were studied. The results indicate that the analysis results exhibit good agreement with the experiment data. The axial load level is the main factor that influences the envelope curve. The stiffness decreases with the incresing of axial load level, while the ultimate lateral load increases with the axial load level less than 0.2, and decreases with the axial load level more than 0.3. The thickness of steel tube has a significant influence on the ultimate lateral load, while has little impact on the shape of envelope curve.

Experimental investigation of free head model piles under lateral load in homogenous and layered sand

Model pile tests were carried out and subsequently the experimental study was supplemented by numerical study to determine coefficient of horizontal modulus of sub-grade reaction (ηh). Both short and long free headed piles were tested in homogeneous and layered soil media. Relative density of sand, slenderness ratio (SR), and embedment ratio of pile (thickness of top weaker layer) were varied. The numerical study was done by three-dimensional finite element method with the help of PLAXIS 3D Foundation version 2.1 software. Then, finite difference method was applied on the deflection profile along pile depth obtained from output of finite element analysis to determine ηh, the coefficient of horizontal modulus of sub-grade reaction. In finite element analysis, the test conditions were simulated and variables of the same soil–pile parameters were considered as in case of the experimental study. The numerical results were found to agree considerably well with the experimental ones for both long and short piles in homogeneous and layered sand media. Subsequently, variation of ηh was studied with the soil–pile parameters as mentioned. The variation of normalised form of ηh, defined as flexibility ratio with different soil–pile parameters, was also studied. At the outset, some behavioural changes were noted for long and short piles in both homogeneous and layered sand. In case of layered sand medium, ηh increased as the overlying weaker sand layer thickness decreased. However, in case of short piles and long piles, this variation was continuously linear. For short piles, ηh increased with increase in sand compactness and SR of pile, whereas in case of long piles, it increased with sand compactness and decreased with the SR of pile beyond SR of 40. This paper focuses on change on variation of different soil–pile parameters on ultimate lateral load as well as coefficient of horizontal modulus of sub-grade reaction (ηh), the principle stiffness parameter, which determines the ultimate lateral load of a single pile.

Hysteretic behavior of multi-cell T- Shaped concrete-filled steel tubular columns

Several multi-cell improvement methods for solving existing problems of conventional T-shaped concrete-filled steel tubular (T-CFST) columns and for determining steel׳s optimal distributions for increasing the strength and ductility of the columns are presented. An experimental study with eight multi-cell T-shaped concrete-filled steel tubular (MT-CFST) columns and one conventional T-CFST column under low frequency cyclic loading was conducted. Effects of the multi-cell layout and the concrete strength on the hysteretic behavior of the specimens were investigated. Experimental results showed that the lateral load-displacement hysteretic curves of the columns were generally saturated with a slight pinching effect. Owing to the asymmetry of the T-shaped cross section, the hysteretic behavior of the composite columns is asymmetrical in different loading directions. The improved MT-CFST columns showed better seismic behavior due to high load bearing capacity, ductility and energy dissipation capacity. Furthermore, the non-linear finite element analysis was performed to simulate the hysteretic behavior of the specimens and the numerical results agreed well with the test results. In conclusion, with an increasing axial load ratio, the ultimate lateral load in the pushing direction gradually decreases and is reached earlier, whereas the ultimate lateral load in the pulling direction increases slightly under low axial ratio and decreases under high axial load ratio.

Experimental and theoretical studies of laterally loaded finned piles in sand

Large lateral loads may act on pile foundation supporting structures, such as bridge abutments, retaining walls, and structures subjected to wind–earthquake loads. A pile with fins is a newly developed type of pile foundation that is capable of supporting large lateral loads. In the present study an attempt is made to evaluate the improvement in lateral capacity of a pile with fins mounted close to the pile head. Small-scale model tests and a numerical study using finite element analysis were performed on regular piles without (fins) and piles with fins. These piles were installed in sand of different relative densities (Dr= 35% and 78%). The investigations were carried out by varying the length, width, and shape of the fins, and type of pile. Results reveal that there is a significant increase in lateral resistance of the piles after mounting the fins close to the pile head. The increase in lateral resistance gained by placing fins on a pile varies with geometries of the pile and fins. The lateral resistance increases with the increase in length of the fins until the fin’s length is equal to 0.4 of the pile length. Based on the results of the laboratory model and numerical analysis, critical values of fin parameters for maximum improvement are suggested. The agreement between observed and computed results is found to be reasonably good in terms of ultimate lateral load and fin efficiency. A comparison between the model results and the prototype-scale results is also studied.

Strengthing of Low Ductile Reinforced Concrete Frame Using XBracing with Different Details

Structures in high seismic risk areas may be vulnerable to severe damage in a major earthquake. Structures designed to meet older code necessities may be at even greater risk. When these structures are evaluated with respect to current code criteria, it is observed that they lack of lateral strength or ductility. Since safety and economic considerations are major problems, these structures become viable candidates for retrofit and seismic strengthening. Diagonal bracing system is one of the retrofitting techniques and it provides an excellent approach for strengthening and stiffening existing building for lateral forces. Also, another potential advantage of this system is the comparatively small increase in mass associated with the retrofitting scheme since this is a great problem for several retrofitting techniques. In this study, the use of steel bracing for the strengthening of low, intermediate, and relatively low ductile reinforced concrete frames are investigated analytically. The ultimate lateral load capacities of the strengthened frames are determined by a load controlled static analysis. The tension member design based on IS: 800:2007 code and check its strength under earthquake loading.

Experimental Investigation of Flax FRP Tube Confined Coconut Fibre Reinforced Concrete

The compressive and flexural performance of flax fibre reinforced polymer (FFRP) confined coconut fibre reinforced concrete (CFRC) structures were investigated. The mass content of coconut fibre considered was 1% of cement. Eighteen cylinders were tested under uniaxial compression and 12 beams were tested under four-point bending. Test results show that in compression, both FFRP tube and FFRP wrapping confinements enhance the axial compressive strength and ultimate strain of concrete significantly, e.g. the ultimate strength of 4-layer FFRP tube confined CFRC is 94% larger than that of the unconfined CFRC. In flexure, the FFRP tube increases the lateral load bearing capacity and the deflection several times larger than the unconfined concrete columns, e.g. the ultimate lateral load of 4-layer FFRP confined PC and CFRC are 1066% and 946% larger than the corresponding unconfined PC and CFRC specimens. In flexure, coir inclusion can affect the failure mode of the FFRP-CFRC composite structure significantly.

Investigation of Static Laterally Loaded Pile in Layered Sandy Soil

Investigation of the static lateral load resistance of pile on layered sandy soil was made by laboratory model test on single pile. The experiment was carried out with variable diameter and variable embedded length of pile on sandy soil. In this study, model pile was single pile which satisfies the Meyerhof’s Relative Stiffness limit of pile for flexible pile. Single pile embedded length, L=0.46m, 0.609m, 0.762m for pile diameter, d=0.013m, 0.019m, 0.026m, respectively. And for surcharge condition embedded length of single pile, L=0.609m and surcharge of pressure, P=3369.55Kg/m3, P=6739.1 Kg/m3 and P=13478.20Kg/m3 for each diameter and for saturated condition of pile diameter, d=0.013m. These experiments were conducted with local sand of Rajshahi region and domar sand; available in Bangladesh. Lateral static loads were applied in the single by a static lateral load set up arrangement. Due to the static lateral load the pile was deflected. The load-displacement response, ultimate resistance of pile has been qualitatively and quantitatively investigated in the experiment. The lateral resistance of pile obtains by experiment and the ultimate lateral load resistances obtained by analytical methods were compared. The load displacement curves are similar and non-linear. Lateral failure at a pile head displacement from 8 to 10, 7 to 9 and 6 to 8mm for single pile of d= 0.013m, 0.019m and 0.026m, respectively. In the case of saturated condition of sand a pile head displacement 15mm for single of d=0.013m. It observed that the failure load was the point at which the curve exhibits a pick or maintains continuous displacement increase with no further increase in lateral resistance. DOI: http://dx.doi.org/10.3329/jsf.v8i1-2.14630 J. Sci. Foundation, 8(1&2): 83-88, June-December 2010

Limit State Strength of Unreinforced Masonry Structures

This paper presents a new formula to estimate the ultimate lateral force of unreinforced masonry structures. The ratio of the wall's height to the wall's width is used to predict the ultimate lateral load of the wall. The coefficient is determined by the numerical implementation of an interface model to simulate the behavior of mortar joints in masonry walls. The numerical predictions are compared with the FEMA guidelines and the experimental data. The comparisons show that the loads that are predicted by the proposed formula have a lower error percentage than the FEMA guidelines. Thus, the proposed formula can be used to analyze unreinforced masonry structures.

An Experimental Study on Pile Spacing Effects under Lateral Loading in Sand

Grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. Ultimate lateral resistance and lateral subgrade modulus within a pile group are known as the key parameters in the soil-pile interaction phenomenon. In this study, a series of experimental investigation was carried out on single and group pile subjected to monotonic lateral loadings. Experimental investigations were conducted on twelve model pile groups of configurations 1 × 2, 1 × 3, 2 × 2, 3 × 3, and 3 × 2 for embedded length-to-diameter ratio l/d = 32 into loose and dense sand, spacing from 3 to 6 pile diameter, in parallel and series arrangement. The tests were performed in dry sand from Johor Bahru, Malaysia. To reconstruct the sand samples, the new designed apparatus, Mobile Pluviator, was adopted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. An increasing of the number of piles in-group decreases the group efficiency owing to the increasing of overlapped stress zones and active wedges. A ratio of s/d more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.

Hysteretic Behavior of Steel Column Strengthened With CFRP in Thermal Environment

This paper is concerned with analysis for the strengthening effect of carbon fiber-reinforced polymer (CFRP) on steel columns under cyclic lateral loading in thermal environment. Based on the finite element theory of thermo-elastic problem and steel structure stability theory, the hysteretic behavior of axial compression steel columns was studied by using Ansys software. The main variables investigated are: cyclic lateral loading, temperature, axial compression ratio and ductility. The results show that the CFRP wraps can improve the ultimate cyclic lateral loading and ductility of steel columns prominently in thermal environment which benefit to the anti-seismic capacity of steel structure. The effect of axial compression ratio on ultimate cyclic lateral loading is very obvious, more enhancements achieved with the axial compression ratio increased. While effect of temperature on ultimate cyclic lateral loading is not very obvious below 300℃. DOI: http://dx.doi.org/10.11591/telkomnika.v10i5.1278

Hysteretic Behavior of Steel Members Strengthened with CFRP under Cyclic Lateral Loading in Different Temperature

With the development of strengthening and repairing technology, carbon fiber-reinforced polymer (CFRP) has been widely applied in concrete and masonry structures for high efficiency. However, there is limited information about how they can be used to strengthen steel members. This paper presents the strengthening effect of CFRP on steel column under cyclic lateral loading in thermal environment. The results indicate that application of CFRP in steel column under cyclic lateral loading in thermal environment has substantial benefits. In particular, the CFRP wraps can improve the ultimate cyclic lateral load and ductility of steel column prominently in thermal environment which can meet the higher requirements of stiffness.

Estimation of Ultimate Lateral Load Capacity of Piles in Sands Using Calibration Chamber Tests

Abstract Current practice for the estimation of the ultimate lateral load capacity of piles is typically based on the vertical effective stress σ′v, while the effect of the lateral effective stress σ′h is not specifically considered. In the present study, calibration chamber lateral pile load tests are conducted to investigate the load response and ultimate lateral load capacity Hu of laterally loaded piles under various soil and stress conditions. In order to determine Hu from load-deflection curves, different criteria are explored and analyzed. From the test results, it is shown that Hu increases significantly with increasing σ′h for a given σ′v. It is also found that lateral deflection of pile at ultimate state tends to increase as the relative density and lateral stress increase. On the basis of the test results, the lateral stress correction factor reflecting the effect of the lateral effective stress σ′h on Hu is proposed. From the test results, it is seen that the proposed procedure using the lateral stress correction factor produces more realistic estimation of Hu. Case examples are selected from the literature and used to compare results measured and predicted using the proposed approach.

The Gusset Plate Effect in Steel Plate Shear Wall Systems

A steel plate shear wall dual system consists of a moment resisting frame plus thin infill shear panels. In the literature, it is stated that the ultimate lateral load bearing capacity of such a dual system can be evaluated by a simple addition of the discrete frame, brought about by the formation of plastic hinges and that of detached infill panel evaluated when yield patterns form along their diagonal tension folds. However, more recent studies show that there is an interaction effect between the wall and the frame and that the combined system can resist additional loads. In other words, the principle of superposition does not apply to this dual lateral load resisting system. This super added value may arise from two factors: (a) the influence of beam and column rigidities on the buckling and ultimate load bearing capacity of panel, and (b) the influence of the panel on the frame. This article studies the latter effect, otherwise known as the gusset plate effect in shear-walled frames.