Multidirectional Loading Research Articles

The seismic resistance simulation for cracked clayey backfill

Applying nonlinear multidirectional forces to the earth retaining structure causes expansion and compression of existing soil crack and this phenomenon occurs in complicated form for clay. The cracked clayey backfill subjected to multi-directional seismic loads has not been reported in the literature. An analytical method was used for identifying the length of the crack. Two types of models with 7 and 15 cracks were assumed and simulated. By introducing the nonlinear extended finite element method (NXFEM), the nonlinear displacement, strain, and stress of the models were simulated. The results revealed that the number of the soil cracks modifies the vibration mechanism, nonlinear displacement, stress, and strain behavior of the model. The research methodology was validated by comparing the results of the numerical simulation with those available in the literature. The novelty of the present study is related to introducing NXFEM.

A MODIFIED FINITE ELEMENT MODEL OF A POROVISCOELASTIC INTERVERTEBRAL DISC

The intervertebral disc (IVD) is the soft tissue between the vertebral bodies, which is responsible for transmitting multi-directional loads through the spine and to allow relative motion between the vertebral bodies. The IVD is composed of three distinct tissues, including the nucleus pulposus, annulus fibrosus, and the cartilaginous endplates. Each of these tissues has a characteristic composition and structure which provide them with unique mechanical properties. Among these, nucleus pulposus and annulus fibrosus due to their intricate time-dependent mechanical response has always been the topic of interest for the researchers. Here, we aimed at establishing a patient-specific 3D finite element (FE) model of human IVD based on the poroviscoelastic constitutive law. The main objective was to use the data of tensile stress-relaxation tests on the annulus and nucleus regions to find the poroviscoelastic material constitutive law. The model assumed that the disc is a two-phase body consisting of a water-saturated solid matrix. To do that, the available data in the literature was used as the primary material properties of our model. Thereafter, a set of compressive and tensile loadings was applied on the established patient-specific model of the IVD and the FE results of the poroviscoelastic model were compared to the experimental data. This allowed us to determine a new set of revised parameter values for the poroviscoelastic model which will have practical implications for any future FE studies.

Prediction of Bidirectional Shear Strength of Rectangular RC Columns Subjected to Multidirectional Earthquake Actions for Collapse Prevention

The understanding of the effects of multidirectional loadings imposed on major load bearing elements such as reinforced concrete (RC) columns by seismic actions for collapse prevention is of utmost importance, and a few simplified models are available in the literature. In this study, the distinguishing features of two machine-learning (ML) methods, namely, multi expression programming (MEP) and adaptive neuro-fuzzy inference system (ANFIS) are exploited for the first time to develop eight novel prediction models (M1-to M4-MEP and M1-to M4-ANFIS) with different combinations of input parameters to predict the biaxial shear strength of RC columns (V). The performance of the developed models was assessed using various statistical indicators and by comparing them with the experimental values. Based on the statistical analysis of the developed models, M1-ANFIS and M1-MEP performed very well and exhibited the best overall efficiency of the studied ML methods. Simple mathematical formulations were also provided by the MEP algorithm for the prediction of V, using which the M1-MEP model was finalized based on its performance, accuracy, and generalization capability. A parametric analysis was also performed for the model to show that the mathematical formulation provided by MEP accurately represents the system under consideration and is imperative for prediction purposes. Based on its performance, the model can thus be recommended to update the current code provisions and engineering practices.

Parametric investigation on the effect of sloping topography on horizontal and vertical ground motions

This study investigates the effect of slope site conditions on ground motion amplification based on the seismic response analysis of 3D finite element slope models with different soil types and multidirectional seismic loadings. The numerical results indicate that the amplification ability of the lateral infinite extension slope model on the horizontal x- and y-components of input motion is equivalent and slightly less than that of the vertical component. Then, the effects of several site parameters (soil type, slope height, slope angle and peak acceleration of input motion) on topographic amplification of ground motions are discussed. The ability of topographic amplification decreases with increasing soil's shear wave velocity or peak acceleration of input motion. In addition, the amplification ability does not increase monotonously with increasing slope height or slope angle. Finally, the relationships between the evaluation indices and the distance from the slope crest are discussed. The results show that the maximum topographic amplification factor predominantly occurs near the slope crest within x/H = 1.5, and the correction factor defined in the Chinese seismic code could be insufficient for slope sites with low shear wave velocity soils.

Research on Factors Affecting Mine Wall Stability in Isolated Pillar Mining in Deep Mines

This study takes the Dongguashan Copper Mine as its engineering background. Based on the mechanical model of the mine wall under the trapezoidal load of the backfill, a comprehensive evaluation index is proposed, and its calculation equation is derived. On this basis, an orthogonal test is designed to explore the influence of mining design parameters on mine wall stability. The results show that the width of the mine wall is the main factor affecting its stability, and increasing the width of the mine wall can significantly improve its stability. When the width of the mine wall is kept above 4 m, its stability is better. When the mechanical parameters of the backfill are poor, the mine wall is prone to overturning failure. The width of the mine room has an influence on the multi-directional loading of the mine wall, but the influence on the stability of the mine wall is low. According to the regression equation calculation, the mine wall safety factor is about 1.46 under the design of G5 mining of Dongguashan Line 52, the stability of the mine wall is good after actual mining and the engineering application effect is ideal, which can provide a theoretical basis for the design of isolation pillar mining in deep mines.

Liquefaction behavior of fiber-reinforced calcareous sands in unidirectional and multidirectional simple shear tests

A study on the liquefaction resistance of calcareous sands reinforced with polypropylene fibers was reported. Stress-controlled cyclic simple shear tests were conducted on specimens prepared at a relative density of 50%, with and without fiber reinforcements. The liquefaction behavior was investigated by considering the effects of fiber contents ranging from 0% to 1%, fiber lengths varying from 3 mm to 12 mm and loading patterns. The results indicated that increasing fiber content and fiber length resulted in a decrease in the deformation, a reduction in pore pressure accumulation rate, and improved the liquefaction resistance of calcareous sands. Additionally, the risk of soil liquefaction could be significantly reduced when the fiber content was greater than 0.8%. The multidirectional loading had a considerable effect in reducing the liquefaction resistance compared to unidirectional loading. Further, the stiffness degradation of calcareous sands decreased with increasing fiber content and fiber length. The pore pressure generated in the cyclic tests was analyzed and was found to be affected by fiber content. A pore pressure prediction model was proposed to obtain the pore pressure characteristics of fiber-reinforced calcareous sands under various fiber content conditions.

Numerical research on the interaction of multi-directional random waves with an offshore wind turbine foundation

Real sea waves are multi-directional, but most studies on wave–structure interaction have focused on unidirectional waves. In this study, a coupled model between a potential flow solver and OpenFOAM wave basin is adopted to investigate multi-directional wave loads on an offshore wind turbine foundation. The coupled model is extended to multi-directional wave states based on the single summation method combined with the JONSWAP spectra. The numerical results are validated against the experimentally obtained values. Multi-directional waves are short-crested, the elevations are random in the wave field, and the wave pressures induced on the two sides of the cylinder are not symmetric about the principal wave direction, leading to a non-zero transverse force. In addition, the effects of wave directionality and relative ratio of foundation diameter and wavelength on wave loads are analysed. For multi-directional waves, the effects of wave directionality on transverse wave force are more sensitive than those on normal force. Wave run-up on the up-wave side increases as the directional spreading parameter decreases. In addition, wave directionality plays a complex role in the wave run-up load induced on the back side, which is found to be controlled by the relative ratio of the cylinder diameter and wavelength.

On the Vibration, Buckling and Dynamic Stability of Three-Directional Functionally Graded Circular Cylindrical Tubes with Consideration of Higher-Order Beam Theory

In view of engineered structures such as those of advanced aircraft and space shuttles are often required to withstand multidirectional loads. We present three-directional (3D) functionally graded materials (FGMs) to reconstruct circular cylindrical tubes placed on an elastic foundation, and the buckling, dynamic and stability behaviors are investigated. In contrast with those of unidirectional and bidirectional FGMs, the material properties of 3D FGMs are designed to vary continuously and smoothly in three directions to fulfill multifunctional requirements. Considering the higher-order beam theory, Hamilton’s principle is adopted to establish the governing equations with variable coefficients of the 3D FGMs tubes. The generalized differential quadrature method (GDQM) is used to predict the statics and dynamics. Numerical simulations are performed to obtain the effects of physical parameters, such as the 3D FGM indexes, on the natural frequency, buckling load and stability regions in detail. The results show that the mechanical behaviors of the circular cylindrical tubes can be easily tuned by introducing 3D FGMs, demonstrating that 3D FGMs have more potential than one-directional and two-directional FGMs in terms of improving the load-bearing capacity of structures and optimizing those structures.

Effects of the Ankle Flexion Angle During Anterior Talofibular Ligament Reconstruction on Ankle Kinematics, Laxity, and In Situ Forces of the Reconstructed Graft.

This study aimed to evaluate the effects of the ankle flexion angle during anterior talofibular ligament (ATFL) reconstruction on ankle kinematics, laxity, and in situ force of a graft. Twelve cadaveric ankles were evaluated using a 6-degrees of freedom robotic system to apply passive plantar flexion and dorsiflexion motions and multidirectional loads. A repeated measures experiment was designed using the intact ATFL, transected ATFL, and reconstructed ATFL. During ATFL reconstruction (ATFLR), the graft was fixed at a neutral position (ATFLR 0 degrees), 15 degrees of plantar flexion (ATFLR PF15 degrees), and 30 degrees of plantar flexion (ATFLR PF30 degrees) with a constant initial tension of 10 N. The 3-dimensional path and reconstructed graft tension were simultaneously recorded, and the in situ force of the ATFL and reconstructed grafts were calculated using the principle of superposition. The in situ forces of the reconstructed grafts in ATFLR 0 degrees and ATFLR PF 15 degrees were significantly higher than those of intact ankles. The ankle kinematics and laxity produced by ATFLR PF 30 degrees were not significantly different from those of intact ankles. The in situ force on the ATFL was 19.0 N at 30 degrees of plantar flexion. In situ forces of 41.0, 33.7, and 21.9 N were observed at 30 degrees of plantar flexion in ATFLR 0, 15, and 30 degrees, respectively. ATFL reconstruction with the peroneus longus (PL) tendon was performed with the graft at 30 degrees of plantar flexion resulted in ankle kinematics, laxity, and in situ forces similar to those of intact ankles. ATFL reconstructions performed with the graft fixed at 0 and 15 degrees of the plantar flexion resulted in higher in situ forces on the reconstructed graft. Fixing the ATFL tendon graft at 30 degrees of plantar flexion results in an in situ force closest to that of an intact ankle and avoids the excessive tension on the reconstructed graft.

Informed Finite Element Modelling for Wire and Arc Additively Manufactured Metallics—A Case Study on Modular Building Connections

The use of 3D printing in modular building connections is a novel and promising technique. However, the performance of 3D printed steel modular building connections has not been investigated adequately to date. Therefore, this paper presents a three-dimensional finite element model (FEM), using the multi-purpose software Abaqus, to study the effect of different geometrical and material parameters on the ultimate behaviour of modular building connections (herein named 3DMBC) using a wire and arc additive manufacturing (WAAM) method, as part of the UK’s 3DMBC (3D Modular Building Connections) project. The proposed model considers material and geometrical non-linearities, initial imperfections, and the contact between adjacent surfaces. The finite element results are compared with the currently available experimental results and validated to ensure developed FEM can be used to analyse the behaviour of 3DMBC with some adjustments. Case studies were investigated using the validated model to analyse the ultimate behaviour with different nominal and WAAM-produced materials under various loading arrangements. Based on the results, it is recommended to conservatively use the treated or untreated WAAM material properties obtained in θ = 90° print orientation in the finite element modelling of 3DMBCs considering the complex component arrangements and multi-directional loading in the modular connections. It is also noted that the thickness of beams and columns of fully 3D printed connections can be increased to achieve the same level of performance as traditional modular connections. For the 3DMBCs printed using untreated WAAM, the thickness increment was found to be 50% in this study.

A unified model of ductile fracture considering strain rate and temperature under the complex stress states

In the thermoforming process of complex components, such as the multi-directional loading forming of multi-cavity parts, complex stress states always exist and change. Meanwhile ductile fracture is prone to occurring, which is sensitive to stress state, as well as deformation temperature and strain rate. This makes fracture behavior very complex and prediction for it difficult. In this paper, a new type of fracture test device was developed, also a trapezoidal groove shape (TGS) specimen was ingeniously designed to change the stress state from tension-shear to pure shear and compression-shear only by increasing the groove bridge angle β. The fracture behaviors of AA7075-H112 under strain states 0.04s−1∼1s−1 and temperatures 20 °C∼450 °C were studied, and the fracture mechanism was identified as a mixture of surface shear and core tensile fracture, but an increasing β promoted the formation and proportion of shear plane and finally led to shear fracture. Based on this, a shear-dominated DF2014 model was determined as the basic framework, then the temperature and strain rate terms of Johnson-Cook fracture model were referenced and modified to be introduced, and finally a unified thermoforming fracture model under various complex stress states was established. The full set of model parameters was determined by a hybrid experimental-numerical method and the predictions of model were verified to match the experimental ones. Then the distribution of critical equivalent strains to fracture was presented in space of stress triaxiality and Lode parameter, which showed a good predictive capability over a wide stress state range with low stress triaxialities.

Numerical modeling of soil–pipe interaction of single pipeline at shallow embedment in clay by hypoplastic macroelement

Nowadays, the numerical analysis of submarine pipelines of offshore oil and gas industry is a big challenge in engineering design. A simple, fast and accurate numerical tool is proposed in this article based on the macroelement concept. The novel macroelement is within the framework of hypoplasticity and can consider static monotonic combined (multi-directional) loads for shallow embedded pipelines in clay. The incremental nonlinear constitutive formulas are defined in terms of generalized forces and displacements and an enhanced function of failure surface is introduced. A series of empirical formulas are proposed to describe the stiffness variation trends for soil–pipeline interaction. Model predictions show that the proposed macroelement is proved to be an efficient alternative approach compared to the traditional finite element analysis. The computational cost is thus much reduced for the pipeline design.

Influence of seam structural parameters on seam strength under unidirectional and multi-directional load exertions

In the present study, seam failure mechanism has been investigated as a result of fabric exposure to unidirectional and multi-directional loads, considering the seam structural parameters, such as stitch type and length. To this end, three common groups of fabrics, namely worsted, shirting and dress woven, have been examined and the effect of seam properties and its interaction with fabric type is analysed through the measurement of seam’s unidirectional and multi-directional strengths and the seam efficiency. The results show that stitch type and length have a significant effect on the tensile properties of seams. Suitable selection of stitching parameters can enhance the seam performance at unidirectional and multi-directional loadings and improvement of the seam efficiency.

Numerical model for 3D steel moment frames with H-shaped beams and hollow-section columns under multi-directional seismic ground motions

In Japan, steel moment frames comprising H-shaped beams and square hollow-section columns with through diaphragms are often used for low- to middle-rise building structures. The column overdesign factor—strength ratio between columns and beams—is specified as ≥1.5 in Japanese seismic design code to ensure adequate energy absorption capacity against bidirectional ground motion by achieving an entire beam-hinging collapse mechanism. However, the required column overdesign factor of steel moment frames is obtained from analysis results conducted under unidirectional ground motions.Additionally, the numerical models of most previous studies considered the behavior of only beams and columns, and ignored the behavior of the panel zone of the beam–column connection. Nevertheless, the panel zone may yield with the beams and columns under severe earthquakes. In addition, the influence of panels on steel moment frames subjected to bidirectional ground motion is not completely understood, as a numerical model for panels under bidirectional shear forces and biaxial bending moments is yet to be proposed.Thus, this research proposes a novel numerical model for studying steel moment frames under multi-directional loadings to consider the 3D elastoplastic behavior of beams and columns, as well as panels. The proposed numerical model was validated by analyzing cruciform subassemblies of beams, columns, and panels, and the analysis results were compared to the experimental results from previous studies. Furthermore, a time-history response analysis was conducted for the 3D steel moment frames, and the energy dissipated from the plastic deformation of the beams, columns, and panels within each beam–column connection was discussed from the aspect of strength ratios between structural members.

Seismic Performance of Hollow Bridge Pier Columns under Multi-Directional Loading

Seismic Performance of Hollow Bridge Pier Columns under Multi-Directional Loading

P10. Sub-regional analysis of principal strains across the intact L3-4 disc during in vitro multi-directional loading using 3D digital image correlation (DIC)

P10. Sub-regional analysis of principal strains across the intact L3-4 disc during in vitro multi-directional loading using 3D digital image correlation (DIC)

P8. Correlations between sagittal plane disc dimensions and principal surface strains across the L3-4 intact IVD during in vitro multidirectional loading

<h3>BACKGROUND CONTEXT</h3> Understanding the biomechanical behavior of the intact intervertebral disc (IVD) is of great importance when studying disc disease. Experimental data describing the relationship between disc size and sub-regional principal strains of the intact lumbar intervertebral disc during multi-directional loading are lacking. <h3>PURPOSE</h3> The purpose of this study was to investigate possible relationships between lateral view disc dimensions and principal surface strains across different regions of an intact L3-4 disc assessed using digital image correlation (DIC) during multi-directional loading. <h3>STUDY DESIGN/SETTING</h3> Correlation analysis of dimensional data obtained from lateral X-rays of intact L3-4 lumbar discs at rest and principal surface strains of the same discs obtained from digital image correlation analysis during in vitro loading. <h3>PATIENT SAMPLE</h3> There were 14 cadaveric spine segments including 6F/8M, mean(±SD) age: 45±13years; BMD: 0.916±0.120 g/cm2. <h3>OUTCOME MEASURES</h3> Correlation coefficients (and p-values) between disc dimensions (sagittal view disc height and area) and principal surface strains during multi-directional loading, in sub-regions of intact L3-4 IVD. <h3>METHODS</h3> The mean height and depth of the L3-4 IVD of 14 seemingly healthy human spine segments at rest were determined using lateral view X-rays and ImageJ. The IVDs were part of L3-S1 spine segments that were tested using non-destructive loading (7.5 Nm) in flexion (FL), extension (EX), right lateral bending (RLB) right/left axial rotation (RAR/LAR), followed by compression (Comp, 400 N). Mean principal strains (Pmax and Pmin) in four similarly sized quarters of the L3-4 IVD were assessed using 3D DIC (Vic-3D) during loading with cameras positioned directly lateral on the specimen's left side. Relationships between sagittal view disc dimensions at rest and mean principal strains per lateral view disc quarter [Q1(ant)-Q4(post)] during loading were studied using Pearson Correlation analysis (SigmaPlot v14 with p<0.05). <h3>RESULTS</h3> Disc height correlated significantly and positively with Pmax (tensile/stretching strain) mid-anteriorly (Q2) during Comp (R=0.545, p=0.044). There were no other significant correlations between disc height and principal strains in any other region of the disc during any direction of loading (p>0.05). In the mid-posterior disc region (Q3), Pmax correlated significantly and negatively with sagittal plane disc area during FL (R=-0.538, p=0.047) and RLB (R=-0.592, p=0.033, Fig.), showing that a larger disc (taller and deeper) bulges/stretches less during flexion and right lateral bending than a smaller disc (narrow disc height combined with shorter vertebral depth, anterior-posteriorly), mid-posteriorly. Pmin (compressive strain) correlated significantly and positively with sagittal plane disc area in the mid-posterior disc region during Comp (Q3: R=0.650, p=0.012; and Q4: R=0.619, p=0.018), indicating that a larger disc (taller and deeper) shrinks less vertically than a small disc posteriorly during compression. <h3>CONCLUSIONS</h3> Significant relationships were found between disc dimensions and mean principal strains in sagittal view sub-regions of the L3-4 intervertebral disc, during different directions of loading. These relationships aid in understanding intact disc biomechanical behavior during loading and will help improve the quality of finite element models of lumbar spine segments. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P5. Fixation stability of four different cervical disc prostheses endplate configurations

<h3>BACKGROUND CONTEXT</h3> Motion preservation devices have become increasingly popular in the treatment of spinal pathologies that require biomechanical support following removal of the degenerated tissue. As these devices continue to be developed to treat multiple adjacent diseased spinal levels, like the use of multiple disc prostheses or placement of a disc prosthesis adjacent to a fused level, in-depth biomechanical data that supports these established surgical methods are needed. <h3>PURPOSE</h3> To assess immediate stability of four cervical disc prostheses under low endurance multidirectional cyclic loading conditions in a cadaveric cervical spine model. <h3>STUDY DESIGN/SETTING</h3> Each prosthesis was implanted in a cervical functional spinal unit (FSU) and cyclically loaded 2000 times under physiological ranges of combined flexion/extension coupled with axial rotation at a rate of 2.5deg/s. <h3>PATIENT SAMPLE</h3> There were 16 (C4-C5) and 16 (C6-C7) FSUs dissected from eight male and eight female cadaveric cervical spines with an average age of 55.9 +/- 9.7 years. Three FSUs were not usable due to poor tissue quality which reduced the sample size to 29 FSUs. <h3>OUTCOME MEASURES</h3> A one-way repeated measures ANOVA with a Student Newman-Keuls test was used to compare differences in the combined motion data. Anteroposterior endplate migration of both the upper and lower implant components was measured after 20, 250, 500, 1,000, 1,500 and 2,000 cycles. Tests were stopped if implant component migration exceeded 3mm or endplate fracture was observed, and migrations less than 0.3mm were defined as clinically stable. <h3>METHODS</h3> Four cervical disc prostheses that had a similar ball and socket type articulation mechanism but varying endplate fixation features were tested: 1. A clinically used and FDA-approved single central keel (SCK). 2. A clinically used (outside the U.S.) low profile teeth (LPT) with domed endplate shape to allow a better fit in case of concave vertebral endplate. 3. A clinically used (outside the U.S.) tripod keel (TK) and 4. Small single keel (SSK). A minimum sample size of six implants per prosthesis type were used. Three additional TK disc prostheses and two additional LPT disc prostheses were implanted. Specimens were cyclically tested 2,000 times at a rate of 2.5deg/s to an end limit of 1.5Nm in flexion or extension coupled with 1.5Nm of right and left axial rotation resulting in a total applied moment of 2.25Nm. A one-way repeated measures ANOVA with a Student Newman-Keuls test was used to compare differences in the combined motion data. Anteroposterior endplate migration of both the upper and lower implant components was measured after 20, 250, 500, 1,000, 1,500, and 2,000 cycles. Tests were stopped if implant component migration exceeded 3mm or endplate fracture was observed, and migrations less than 0.3mm were defined as clinically stable. <h3>RESULTS</h3> No statistical difference was found between the combined (flexion plus extension) sagittal plane range of motion or the combined (left plus right) axial motion. All but one of the specimen migration values were below 0.3mm. Upper prosthesis component migration ranged between 0.02mm and 0.08mm and between 0.01mm and 0.04mm for the lower components. No significant differences occurred between the upper components or the lower prosthesis components of any implant type. <h3>CONCLUSIONS</h3> Three different low profile endplate fixation designs for a cervical disc were found to provide comparable immediate holding strength to an existing FDA-approved central-based keel design. <h3>FDA DEVICE/DRUG STATUS</h3> Prodisc C (Approved for this indication), Prodisc C Vivo (Investigational/Not approved), Prodisc C Nova (Investigational/Not approved), Prodisc C SK (Investigational/Not approved).

Three-dimensional shear-flexure interaction model for analysis of non-planar reinforced concrete walls

This paper presents theoretical formulation and results of experimental validation studies of a novel three-dimensional macroscopic nonlinear model that captures the interaction between axial-flexural and shear behavior in reinforced concrete (RC) walls. The original Shear-Flexure-Interaction Multiple-Vertical-Line-Element-Model (SFI-MVLEM) developed previously by the authors, which is essentially a two-dimensional line element for rectangular walls subjected to in-plane loading, is extended in this study to a three-dimensional model formulation (SFI-MVLEM-3D) by applying geometric transformation of the element degrees of freedom that convert it into a four-node element, as well as by incorporating linear elastic out-of-plane behavior based on Kirchhoff plate theory. The proposed three-dimensional, four-node model element is implemented in the official version of open-source analysis software OpenSees and validated against experimental data obtained for four well-instrumented U-shaped wall specimens tested under complex multidirectional loading protocols. Comprehensive and detailed comparisons were conducted between various experimentally-measured and analytically-predicted wall responses including the load-displacement behavior of the wall specimens in various loading directions, contributions of nonlinear flexural and shear deformations to wall displacements, vertical and horizontal profiles of flexural strains, and crack patterns. Results presented demonstrate that the proposed analytical model captures, with good accuracy, most of the experimentally-measured responses of non-rectangular walls subjected to multidirectional loading. Model predictions of the wall lateral load capacity and local responses (strains) are, although reasonable, relatively less accurate when the walls are subjected to diagonal loading conditions, due to the plane-sections-remain-plane assumption implemented in the proposed model formulation that disregards the experimentally-observed shear lag effect.

Finite Element Modeling of Reinforced Concrete Walls Under Uni- and Multi-Directional Loading Using Opensees

ABSTRACT A new three-dimensional finite element modeling methodology for nonlinear analysis of reinforced concrete walls is developed and implemented in OpenSees software. The model is validated against broad experimental data obtained for nine planar (unidirectional loading) and two U-shaped (multidirectional loading) specimens. Results of the detailed validation studies presented indicate that the proposed model can accurately capture a wide range of measured global (e.g., load-deformation) and local (e.g., strains) wall responses. However, the model fails to capture the loss of wall lateral load capacity observed in experiments due to various complex failure mechanisms that are not incorporated in presented model formulation.