Lateral Load Behavior Research Articles

Experiment and analysis on seismic performance of a self-centering Y-eccentrically braced frames structure

Conventional eccentrically braced frames (EBFs) exhibit significant residual deformations following major earthquakes, necessitating costly repairs for the damaged structures. This study proposed a novel self-centering Y-eccentrically braced frames (SC-YEBFs) system to enhance the seismic resilience. A theoretical mechanical model which takes into account its components is formulated to predict the lateral load behavior of SC-YEBFs. The pseudo-static experiments were conducted on four specimens, and the resulting observations and analyses demonstrate that the shear links effectively function as ductile fuses, dissipating a significant portion of the input energy to safeguard the main frame from damage. Furthermore, the self-centering joint exhibits a hinge-like behavior with remarkable self-centering characteristics. The structural reparability of all specimens was found to be exceptional during major seismic events. By increasing the initial prestress and sectional area of steel strands, the self-centering performance can be further enhanced. The damaged shear links could be easily detached by loosening bolts, and the consideration of prestress loss is nonnegligible to ensure an exceptional self-centering performance. The proposed theoretical model predicted the mechanical properties of SC-YEBFs, including lateral stiffness, energy dissipation, and self-centering mechanism, through a comparison with experimental results. Moreover, the theoretical model was utilized to propose an equivalent simulation method for simulating self-centering joint and shear link using Connector function in ABAQUS software, while establishing a simplified frame finite element model for further analysis.

Macro-modelling of GFRG infilled RC frames incorporating pivot hysteretic model

GFRG (Glass Fibre Reinforced Gypsum) panels present a viable alternative to conventional masonry infills in masonry infilled RC frames. Based on the experimental study on the lateral load behaviour of GFRG infilled RC frames, it was understood that the GFRG panels enhance the structural performance of the RC framed structure. To delve further into this, numerical modelling of GFRG infilled RC frames with different fillings inside the cavities of the panel was performed using SAP2000. The GFRG panels were modelled using nonlinear layered shell elements, while the interface between the GFRG web and the infill material was represented using multilinear plastic link elements. The monotonic lateral load–deflection behaviour and the in-plane hysteresis response were simulated by performing monotonic and cyclic pushover analyses. The cyclic pushover analysis incorporated pivot hysteretic models for the materials, hinges and links. Validation of the proposed numerical models was carried out by comparing the results with those obtained from the experimental study. Key parameters such as peak load, initial stiffness, stiffness degradation, and energy dissipation were carefully compared to ensure the accuracy and reliability of the proposed model. It was observed that the proposed numerical model was able to capture the monotonic and cyclic load–deflection behaviour and other performance parameters. The numerical model accurately predicted the peak load in the positive direction but overestimated the corresponding value in the negative direction. Moreover, the overestimation observed in the cumulative energy dissipated for all the specimens is relatively minor and does not significantly affect the overall accuracy of the model.

Lateral Load Behavior Analysis of a Novel Self-Centering Y-Eccentrically Braced Frames with Slip Connection Shear Link

Lateral Load Behavior Analysis of a Novel Self-Centering Y-Eccentrically Braced Frames with Slip Connection Shear Link

Design of tie-columns in confined masonry structures for lateral loads

Confined masonry (CM) buildings are generally designed with an expectation that masonry walls withstand all possible loads imparted on the buildings. The reinforced concrete (RC) confining members, also known as tie-members, have the sole purpose of constraining the masonry and avoiding its outward spread during lateral earthquake loading. Reliable design rules for tie-columns are scarce in design codes of CM structures, often resulting in the nominal design of tie-elements without considering the influence of all the important parameters related to the material and geometric properties of CM wall. This often results in the construction of weaker tie-members, especially the tie-columns, that can lead to their direct failure and the failure of the entire wall during earthquakes. To address this issue, a methodology was developed for assessing the design shear forces for the tie-columns as well as masonry subjected to lateral loading by utilizing the past observations from systematic experimental and numerical studies. The efficacy of this methodology was evaluated in the present experimental study conducted on CM walls with varying aspect ratios. The test results demonstrated that the proposed methodology can result in a significant improvement in the lateral load behavior of CM walls, by delaying the shear failure of tie-columns without jeopardizing other functional requirements.

Lateral load behavior of shear connections between steel storage racks and the spine bracing with posts

High-rise steel storage racks are cold-formed thin-walled steel frames, which achieve their lateral strength and stiffness by the use of a spine bracing system in the down-aisle direction commonly located at a short horizontal distance away from the main rack frames. The shear connections between the main rack frame and the spine bracing system play a dominant role in the effectiveness of the spine bracing system. This paper experimentally investigates the behavior of the shear connections used in industrial practice between a steel storage rack and the spine bracing system with posts using four groups of three nominally identical connection specimens. By employing a digital image correlation (DIC) system, the tests generate comprehensive data and establish the real-time deformation fields of individual components of such shear connections. Based on the component-based approach, a linear-elastic analytical model is developed for the type of shear connections under consideration. The proposed analytical model explicitly captures the behavior of the individual connection components, including the three-dimensional flexural bending of endplates, as well as the distortions of the open sections of the upright and the bracing post. Based on the proposed model, this paper quantifies the contribution of each component towards the total deformation of the shear connections. The investigation establishes that the cross-sectional distortion of the bracing post and the out-of-plane bending of the upright web are the most flexible components of such shear connections. Recommendations associated with the shear connections under consideration are proposed for the rack designers and manufacturers.

A multi-strut model for the hysteresis behavior and strength assessment of masonry-infilled steel frames with openings under in-plane lateral loading

The analysis of masonry-infilled frames (MIFs) with openings is a complex problem in structural engineering. Previous studies have shown that when an infill panel has an opening, it behaves as four separate subpanels around the opening. Therefore, it can be conceived that a perforated masonry infill panel behaves as four inclined compression-only equivalent struts in each direction. This paper presents a multi-strut model (MSM) using the equivalent strut concept for the nonlinear analysis of masonry-infilled steel frames (MISFs) with openings. The MSM consists of two inelastic side pier struts connected to the surrounding frame joints using rigid trusses representing the subpanels above and below the opening. The model incorporates an envelope curve and a hysteretic law to define the initial stiffness, peak strength, and post-peak strength behavior of the inclined struts under reversal loads. The MSM was used to analyze the lateral load behavior of tested MISFs with openings found in the literature. It was shown that the proposed model is efficient and can predict the stiffness and capacity of MISFs with openings under both monotonic and cyclic lateral loadings.

Lateral Load Behavior of Self-centering Frame with Y-Eccentrically Braced Substructure: An Experiment and Numerical Analysis

A novel self-centering frame with Y-eccentrically braced structure (SC-YEBFs) has been proposed in this paper to solve the problem that the storey drift of structure may exceed the specified limit in standards when self-centering beam-column joints are applied in high-rise and larger spans buildings, and the SC-YEBFs not only has the self-centering performance of self-centering frame system, but also has the high lateral stiffness and energy dissipating capacity of Y-Eccentrically braced frame. To study the lateral load behavior and influencing factors of SC-YEBFs, cyclic loading tests of two scaled specimens of SC-YEBFs substructure (SCS) were conducted, and seven finite element models corrected by the experiment were established to perform parametric analysis. The experiment and finite element analysis results indicated that the shear link has greatly increased the lateral stiffness and energy dissipating capacity of the self-centering structure, at the same time, it has maintained a good self-centering performance and replace ability. With an increase in the cross-sectional area and initial prestress of post-tensioned steel strands, the lateral load capacity and self-centering performance can be improved. The self-centering performance can be effectively improved by reducing the friction coefficient at the rotation connections. SC-YEBFs further extending the application field of self-centering structural systems, and making it possible to be applied to high-rise and larger spans structures.

Experimental study on the lateral load behaviour of GFRG infilled RC frames

Glass fibre reinforced gypsum (GFRG) panels are light-weight, load bearing wall panels that can be used for the rapid construction of affordable and eco-friendly houses. Numerous studies conducted worldwide have demonstrated the suitability of GFRG panels for constructing walls and slabs. These panels can also be used as infills in multi-storeyed framed construction and the experimental study reported in this paper is perhaps the first of its kind on the lateral load behaviour of GFRG infilled RC frames. Quasi-static cyclic lateral load tests were performed on two full scale 3 m × 3 m GFRG infilled RC framed specimens to gain insights into their lateral load behaviour, crack pattern and other performance parameters. The results confirmed that the failure of the specimens under lateral load primarily occurred in the infill wall, with extensive crack formation observed prior to yielding of the frame members. The experimental study highlighted that infilling the GFRG panels inside the RC frames significantly enhances the strength, stiffness and other performance parameters of the RC framed structure.

Lateral Load Behavior of C-PSW/CFs Using Steel Members as Boundary Elements

Composite plate shear walls/concrete-filled (C-PSW/CFs), also known as SpeedCore systems, are a relatively new structural member in American codes and standards. Prior research has focused primarily on C-PSW/CF walls with either flange/closure plates or filled composite members as boundary elements. Walls without boundary elements have also been studied, but they are no longer permitted by the American Institute of Steel Construction (AISC 341-22). The reason is that composite walls without boundary elements do not provide adequate ductility for seismic design. This paper presents the results of experimental and numerical studies conducted to evaluate the cyclic lateral load behavior of C-PSW/CFs using hot-rolled structural steel members as boundary elements. The steel web plates of the C-PSW/CF specimens were connected to each other using threaded tie bars with double nut connections. Composite interaction between the steel and concrete infill was achieved using the tie bars and additional shear studs welded to the boundary elements. The composite walls were embedded and anchored to reinforced concrete foundation blocks using welded deformed bar anchors. The experimental investigations focused on the cyclic lateral load-drift responses including test observations and limit states, moment-rotation response of the plastic hinge and the section moment-curvature relationship, overall lateral stiffness, strength, and displacement ductility. The experimental results show that the specimens exceeded their nominal flexural capacities calculated using the plastic stress distribution method or fiber-based section modeling using measured material properties. The specimens had plastic hinge rotation capacity greater than 0.028 rad. and displacement ductility ratio greater than 5.2. Detailed 3D nonlinear inelastic finite element models and simpler fiber-based macro models of the tested specimens were developed and benchmarked using experimental results. The detailed 3D finite element models can reasonably simulate the global and local behavior of the specimens, and are recommended for conducting further parametric studies of composite wall design details. Simpler fiber-based macro models can efficiently simulate the cyclic lateral load behavior of the specimens, and are recommended for modeling C-PSW/CFs while simulating the behavior of multi-story building structures.

Behaviour of bio-inspired grouped battered minipiles under lateral loading in clay

The field of bio-inspired geotechnics has been growing in response to the demand for foundations that are sustainable and yet have improved load-bearing capacities. This study aims to address the gap in a specialised adaptation of root system architecture for designing resilient foundations. The lateral load behaviour of one such novel grouped battered minipile configuration is evaluated in this study based on full-scale field testing and numerical modelling to report the unknown increase of load capacity caused by shape modification. First, three single minipiles battered at 0° and 25° were subjected to static lateral loading in fine-grained soil. The strain profiles along the individual minipile shafts were obtained using optic fibre sensors. Consecutively, full-scale lateral load tests on two types of minipile groups were also performed; one group had a configuration of two 25° battered minipiles perpendicular to the direction of loading mimicking a tree-root system, and another conventional group had two positive and negative battered minipiles. A numerical model was developed to investigate the effect of pile spacing and obtain soil pressures, bending moments and axial forces of the battered minipile groups. Results show that increased bearing area and higher engagement of soil volume for the novel minipile group with two perpendicular battered minipiles were larger than the conventional minipile group; thus, the former offered higher lateral resistance. The deflection pattern, bending moment and p-y curves showed a shadowing effect in stiff clay for battered minipile groups at a pile head spacing of three times the minipile diameter.

Formulation of a generalized truss analogy for the analysis of shear behavior of short jacketed columns

Short columns in a story of a reinforced concrete building tend to fail in shear during an earthquake. They can be strengthened using concrete jacketing. A performance-based evaluation requires the modeling of nonlinear lateral load versus deformation behavior of such a column. While previous studies are available to analyze the behavior of a flexure-critical column, computationally simple method of analysis of the shear behavior of a short column is lacking in the literature.A generalized truss analogy is proposed to predict the shear behavior of short columns beyond diagonal cracking and till failure. Its formulation satisfies equilibrium of forces in the concrete strut and reinforcing bar ties, compatibility of strains in the concrete and ties of the web region of a column, and suitable constitutive relationships of the materials. First, the formulation and computation algorithm as applicable to an original column, are presented in this paper. Next, the method is extended to columns strengthened by concrete jacketing. Its application to a composite jacketed section is implemented using a sandwich model.The validation of the proposed method is presented, comparing the predictions with the lateral load versus deflection behavior curves obtained from the tests of five large-scale shear-critical column specimens (two original and three jacketed), tested as part of this research. The good correlation of the predicted and test results confirmed the application of the proposed method for the nonlinear analysis of shear for short columns.

Out-of-Plane behavior of clay brick masonry infills contained within RC frames using 3D-Digital image correlation technique

The present study investigated the out-of-plane (OOP) behavior of traditional solid clay brick masonry-infilled reinforced concrete frames for different slenderness ratios, bonding patterns, and connection details to assess the development of arching mechanism, infill-frame interaction, and failure mechanisms. Full-field strain and crack width analysis, failure progression, and out-of-plane deformation characteristics were evaluated using a non-contact 3D-DIC (digital image correlation) technique. The experimental investigation ascertained that full-brick thick lower slenderness ratio (13.4) specimens observed higher capacity (3.7 times), deformation ability (>1.2 times), and energy dissipation characteristics (>3.5 times) compared to half-brick thick slender (28.8) specimens. The presence of tie bars enhanced the stability of the wall against out-of-plane failure. However, it did not significantly modify the load and deformation behavior in the peak and post-peak stages. The OOP deformation profiles, arching mechanism, and the distributed damage in infill in lower slenderness ratio specimens, which led to higher OOP lateral load resistance, were precisely captured using the 3D-DIC technique. The increase in width of the cracks (1.6–2.9 times) in Flemish bond (lower slenderness ratio) specimens compared to their running bond counterparts was accurately appraised using the DIC. Based on the experimental results, a unified out-of-plane lateral load–deflection idealized model was proposed. The appropriateness of the proposed model was further verified by comparing it with previously developed models and experimental studies. The research study revealed that the out-of-plane lateral load behavior of infilled frames was significantly modified due to strong and stiffer solid clay masonry, considering different structural bonding patterns and slenderness ratios. The 3D-DIC technique was found to be a resourceful tool for comprehending the deformation and damage characteristics of infilled frames, especially under out-of-plane lateral loads.

Analysis of infilled steel frames subjected to lateral loading

In Recent days Earthquake resistant design of structure has earned a lot of scope as Earthquake has become more common. Lateral loading behaviour and energy absorption capacity of monolithic Steel framed structures is significantly affected by Presence of infill which adds to the bracing of the structure, Researchers developed new methods of seismic analysis to analyse the behaviour of structure during occurrence of an Earthquake. Performance based seismic design gives methodology for accessing the performance of structure occupancy, life safety or Collapse prevention level. A non-linear static pushover analysis can be used to analyse the inelastic response of structure to lateral load or displacement. In the present research a 3D model of G + 8 story steel framed building is considered for seismic design and performance evaluation. The model was analysed using ETABS software by response spectrum method for zone V according to IS 1893–2016. The performance is accessed by Capacity Spectrum Method using non-linear pushover analysis. The result of all models are analysed and compared in terms of base shear, story displacement, pushover curve, spectrum curve, performance point of the structure. Overall performance of the structure is found in safer limits.

Finite Element Modeling and Experimental Investigation for Wood/PVC Composites Log-Walls under In-Plane Lateral Load.

This work experimentally determines the in-plane lateral load behavior of a full-scale WPVC composite log-wall, with and without additional through-bolts. The results indicate that the WPVC composite log-wall panel with through-bolts produced higher hysteretic parameter values in terms of strength and energy dissipation than the log-wall without through bolts due to a reduction in wall uplift (48.2% for secant stiffness of cycle, 39.5% for hysteretic energy at the last displacement level). The WPVC composite log-wall panel with through-bolts presented better structural stability and was recommended for investigation. A finite element model (FEM) of a WPVC composite log-wall panel with through-bolts was created using beam elements as log-members and multilinear plastic links as connections, and was verified by the experimental results. The verified FEM was used for further parametric study of wall dimensions and first log-foundation locations. The parametric investigations indicated that increasing panel height and width unfavorably affected lateral load capacity, monotonic and cyclic stiffness, and energy dissipation. The cyclic stiffness decreased by 39% while energy dissipation increased by 78.8%, for the last displacement level when the wall height was increased from 2.350 m to 3.525 m. The cyclic stiffness and energy dissipation of a panel with a width of 6 m decreased 14% and 24.4% compared to a panel with a width of 3.5 m. Moreover, moving log-foundation connections from the original position to the edges of the panel improved performance under monotonic and cyclic horizontal loads; an increase in the number of log-foundation connections had an insignificant effect on panel behavior.

Experimental behaviour of unreinforced and confined rat-trap bond masonry

Rat-trap bond (RTB) masonry is a fast-growing building technique owing to its thermal insulation and cost saving. While cost and energy efficiency are important parameters, structural stability and performance are as important. The aim of this study is to experimentally investigate the behaviour of unreinforced and confined RTB masonry subjected to lateral load. The experimental work consists of in-plane quasi-static cyclic load tests of two full-scale specimens; an unreinforced wall and a confined masonry wall. Key parameters such as lateral strength, stiffness, damping, force-deformation behaviour and ductility modification factor of both specimens are determined to understand the lateral load behaviour of RTB masonry. The experimental results indicate that the addition of confining elements significantly improved the behaviour of RTB masonry by enhancing the lateral strength, stiffness and ductility ratio of RTB walls by 121%, 52.8% and 23.8%, respectively.

Influence of Masonry Infill Wall Position and Openings in the Seismic Response of Reinforced Concrete Frames

It is now widely recognized that the masonry infill frame used in reinforced concrete structures (RC) greatly enhances both the rigidity and strength of the surrounding frame. The lateral loading behavior of this RC frame is different from the frame without infill, although the structural contribution of infill walls is discarded in many countries, including Algeria. This paper aims to focus on the effect of openings and the effect of changing the distribution of masonry panels on the global behavior of buildings. For this, a pushover analysis is carried out to evaluate the seismic performance and assess the behavior of infilled RC, and to study the results related to capacity curve, inter-story drift and energy. The results obtained show that the effect of the openings and changing of the distribution of masonry panels can drastically change the overall behavior of the structures regarding enhancing strength capacities and energy absorption. Noticeable remarks in terms of distributing masonry panels within a frame are observed and several recommendations concerning the present practice might be important to be considered.

Empirical and numerical study of the static lateral response of socketed pile in Dubai, UAE

In geotechnical engineering practice, it is often a challenging task to select a suitable method for the calculation of the lateral load capacity of piles. In Dubai, UAE piles are predominantly rock socketed with top layers commonly medium dense to dense sand or Dubai sedimentary rock contributing to bearing lateral loads. In the present study, the results of two lateral load field tests on piles were selected and used for evaluating various methods adopted by local geotechnical engineers for evaluating lateral load capacity. For the selected piles, the top layers of the ground lithology consist of medium dense to dense sand, which is critical in the evaluation of the lateral capacity of piles. Generally, either the Broms method or p–y non-linear analysis is adopted by local geoengineers for lateral load analysis of piles due to the simple input requirements and quick calculations. With advancement in computing capabilities, geotechnical engineers also adopt numerical analyses. As part of this study, various methods adopted were evaluated in terms of their advantages, limitations and accuracy in predicting the lateral load behaviour of piles. Commonly adopted methodologies such as the Broms method were found to have limitations that underestimate pile capacities, resulting in overdesign of pile sizes leading to higher costs, whereas, comparatively, numerical approaches predict more accurately the lateral load behaviour of piles.

Lateral load behaviour of Glass Fibre Reinforced Gypsum walls supported on Reinforced Concrete frames

Glass Fibre Reinforced Gypsum (GFRG) panel is a light-weight load-bearing hollow building panel, used as structural elements (walls, slabs etc.) with Reinforced Concrete (RC) filled inside the cavities. In GFRG construction, usually all the load bearing walls start from the foundation itself. But the ever-growing issue of land scarcity compels the housing sector to have the provision of parking space at the ground storey of the building. This will require the GFRG walls to be supported on an RC frame structure with columns, beams and slabs. The columns of such a structure can potentially cause a brittle mode of failure under the action of seismic forces, owing to the development of plastic hinges resulting in storey mechanism. The behaviour of such structures under combined gravity and lateral loads (monotonic and cyclic) was evaluated in the present study through quasi-static testing of two full scale specimens. The failure of the specimen under lateral loading was characterised by the failure of wall panel, with extensive crack formation before the yielding of frame members. The test results demonstrated the feasibility of designing GFRG wall on RC frame system without leading to brittle collapse mechanisms.

SC Wall-to-RC Basemat Over-Strength Connection: Behavior and Design

This paper presents results from experimental and analytical investigations conducted to evaluate the lateral load behavior and capacity of steel-plate composite (SC) wall-to-reinforced concrete (RC) basemat connections. Two SC wall-to-reinforced concrete basemat connection specimens were tested. These SC wall specimens had a height-to-length ratio of 0.6 and did not include boundary elements. The experimental results include the lateral force-displacement (V-Δ) responses of the specimens and observations of local damage such as steel plate local buckling and concrete crushing. 3D finite element models were developed and benchmarked using the experimental results. The benchmarked models were used to conduct analytical parametric studies, expand the database, and gain additional insights into the behavior of SC wall-to-RC basemat connections. The parameters included in analytical investigations were the wall aspect ratio (h/lw), reinforcement ratio (ρ), and wall thickness (T).

Lateral loading behavior of the poplar LVL light wood shear wall

Poplar laminated veneer lumber (poplar LVL) is made of fast-growing poplar veneer and structural adhesive, which can well meet the developing requirement of the modern wood structures. This paper mainly focuses on the lateral loading behavior of the poplar LVL shear wall. For this purpose, six shear wall specimens with different opening types were fabricated and tested under the action of monotonic and cyclic loading. Performances were analyzed on the failure pattern, the load-displacement curve, the shear strength, the ultimate displacement, the elastic lateral stiffness, and the energy dissipation. To strengthen the corner joint, an innovative custom-designed hold-down was adopted, and the mechanical performance was also considered. The results showed that the failure of the specimen was mainly due to the yield of the nails and the separation between the stud and the base plate, while the hold-down can greatly improve the shear strength, the ultimate displacement, and the energy dissipation performance of the poplar LVL shear wall without openings. At last, the evaluation formula of the bearing capacity for the light wood shear wall is proposed so as to promote the theoretical basis for the application of poplar LVL in the light wood frame construction.