Monotonic Lateral Loading Research Articles

Shear force demand on headed stud for the design of composite steel plate shear wall

Composite steel plate shear wall (C-SPW) consisting of steel plate with reinforced concrete encasement on one or both sides of the steel plate using headed studs is an effective lateral load resisting system. Previous researches focus mainly on its seismic behavior, while few researchers pay attention to the shear force demand on headed stud, which is an important issue in the design of C-SPW. In this paper, an investigation on the shear force demand on headed stud for the design of C-SPW is carried out by finite element analysis. A novel finite element model incorporating an effective simulation of boundary frame as well as reasonable interaction behaviors of elements is established using ABAQUS and validated in comparison with available tests. The responses of structural elements in C-SPW under monotonic lateral load are investigated. The effects of headed stud diameter, infill steel plate thickness, concrete panel thickness, number of headed studs as well as aspect ratio of shear wall on the maximum stud shear force are analyzed. Based on the analysis results, an available formula for the demand on stud shear force in the design of C-SPW is proposed.

Inelastic behavior of circular concrete-filled steel tubes: monotonic versus cyclic response

In this paper, a computational procedure for determining the response of circular concrete-filled steel tube (CFT) columns to monotonic loading is developed. Firstly, the basis of the proposed method is established by creating accurate three-dimensional nonlinear finite element models of these columns, which are validated by comparing their response results with those of experimental tests that are available in the literature. Then, these models are used for an extensive parametric study that determines the response to monotonic lateral loads of 192 circular CFT specimens with fairly broad values of diameter-to-thickness ratios, yield stress of steel tube, compressive strength of concrete core and axial load levels. On the basis of this response databank, empirical expressions are developed to estimate the force–displacement behavior of circular CFT columns under monotonic loading with simple yet reliable manner. The validity of these empirical expressions is verified by comparing their results with those of experimental tests. It is found that the proposed expressions can effectively describe the force–displacement behavior and capacity of circular CFT columns under monotonic loading conditions. These expressions are also used in pushover analysis of a simple frame consisting of steel beams and CFT columns in order to demonstrate their applicability and usefulness in simple practical problems. Finally, the proposed method, of determining the response of composite structures to monotonic lateral loading is compared with nonlinear time-history response analysis of these structures and useful conclusions are provided.

An investigation of seismic parameters of low yield strength steel plate shear walls

Steel plate shear walls (SPSWs) are effective lateral systems which have high initial stiffness, appropriate ductility and energy dissipation capability. Recently, steel plate shear walls with low yield point strength (LYP), were introduced and they attracted the attention of designers. Structures with this new system, besides using less steel, are more stable. In the present study, the effects of plates with low yield strength on the seismic design parameters of steel frames with steel plate shear walls are investigated. For this purpose, a variety of this kind of structures with different heights including the 2, 5, 10, 14 and 18-story buildings are designed based on the AISC seismic provisions. The structures are modeled using ANSYS finite element software and subjected to monotonic lateral loading. Parameters such as ductility (µ), ductility reduction (Rµ), over-strength (

Seismic Capacity Evaluation of Exterior Shear Keys of Highway Bridges

Shear keys as sacrificial components are widely used in cap beams and abutments of highway bridges to limit the transverse displacement of superstructures and avoid damage of substructures. To investigate the seismic capacity of bridge exterior shear keys, six exterior shear key specimens were designed on the basis of current Chinese seismic design guidelines of highway bridges and subsequently tested under monotonic lateral loading. The influence of vertical and horizontal reinforcement ratios on the seismic capacity of the bridge shear keys was studied. Two typical failure modes of the exterior shear key specimens, diagonal tension failure and sliding shear failure, were observed during the tests. The reinforcement ratios of the shear key and cap beam have significant influence on the seismic capacity of exterior shear keys. Moreover, different analytical models corresponding to the two failure modes were developed to predict the seismic capacity of the shear key specimens in this paper. Compared with the experimental results, the two analytical models proposed in this study can better predict the load-carrying capacity of the shear key specimens than the classical analytical models.

Earth pressures on modified suction caisson in saturated sand under monotonic lateral loading

A modified suction caisson (MSC) can be used to support the offshore wind turbine. This paper presents an experimental study and a numerical simulation on the earth pressure distribution along the MSC embedded in saturated marine fine sand. Results show that the yield envelops for the MSC and the corresponding regular suction caisson in the H-M space can be represented by a linear relationship. It was also found that the Prasad and Chari method, which is popular in analyzing the earth pressure distribution along lateral loaded rigid plies, can well predict the maximum net earth pressure on the regular suction caisson. However, for the MSC, since the external skirt can resist a considerable portion of the lateral load, Prasad and Chari method overestimates the maximum net earth pressures acting on the internal compartmental shaft of the MSC. Numerical simulation results indicate that in the ultimate limit state the maximum net earth pressure acting on the external skirt wall in the loading direction is larger than that on the internal compartment wall. However, the maximum net earth pressure along the caisson embedded depth is obtained at the MSC base opposite the loading direction. In addition, the separation between the top lids of the internal compartment and external skirt occurs opposite the loading direction. The lateral load and the resulting overturning moment acting on the MSC are mainly carried by the passive earth pressure zones along the inner and outer shafts of the internal compartment and the external skirt both in the loading and opposite the loading directions and under the external skirt lid in the loading direction. The main reason of the suction caisson failure is that the sand in the lower passive earth pressure zone opposite the loading direction yields completely.

Cyclic lateral response of FRP-confined circular concrete-filled steel tubular columns

Concrete-filled steel tubular (CFT) columns are widely used as columns in many structural systems and a common failure mode of such tubular columns is inelastic outward local buckling near a column end. The use of fibre-reinforced polymer (FRP) jackets/wraps for the suppression of such local buckling has recently been proposed and has been proven to possess excellent potential in both retrofit/strengthening and new construction. This paper presents the results of an experimental study into the behaviour of large-scale FRP-confined CFT (CCFT) columns under combined axial compression and lateral loading. The test parameters included the stiffness of the FRP jacket and the loading scenario. The test results showed that the FRP jacket can effectively delay or even prevent outward local buckling at the end of a cantilevered CFT column, leading to significantly improved structural performance under combined constant axial compression and cyclic lateral loading. Compared to monotonic lateral loading, cyclic lateral loading was found to introduce more severe localized deformation near the column end and may lead to earlier FRP rupture within that region.

Discussion of “Performance of Hollow Bar Micropiles under Monotonic and Cyclic Lateral Loads” by Ahmed Yehia Abd Elaziz and M. Hesham El Naggar

Discussion of “Performance of Hollow Bar Micropiles under Monotonic and Cyclic Lateral Loads” by Ahmed Yehia Abd Elaziz and M. Hesham El Naggar

BEHAVIOUR OF REINFORCED CONCRETE INFILL PANELS UNDER LATERAL LOAD

Most multi-storey building construction consists of RC frames with UM infills. Traditionally, infills are made of the RCB; however, to reduce Dead Load on the building, RCB are being replaced by AAC and FAB. UM infill is vulnerable element during an earthquake, since it fails by Shear, Sliding and Out-of-plane bending. Behaviour of infill with RCB is well studied; however, studies on infill with AAC and FAB are limited. In the present study, behaviour of different RC infill panels is studied and compared with bare RC frame under monotoniclateral load. RC frame specimens comprising of two columns connected by horizontal beam at top and bottom are developed and tested. Parameters considered for the study are Lateral Displacement, Lateral Stiffness, Failure Load and Patterns. Lateral displacement of all types of RC infill panels are reduced substantially as compared to bare RC frame. RC frame infilled with AAC block shows maximum lateral displacement followed by RC frame infilled with FAB and RCB. RC frame infilled with RCB withstand maximum lateral load while RC frame infilled with FAB withstandthe least load. The failure patterns observed for RC frame with different infills are mostly stepped type and shear type.

Experimental investigation of laterally loaded double-shear-nail connections used in midply wood shear walls

Midply wood shear wall is regarded as a preferable lateral resistance system for timber frame structures. One of the most important reasons is attributed to the good lateral performance of double-shear-nail (DSN) connections. In this study, eight groups of specimens were tested under monotonic lateral loads to investigate the influence of different variables on the lateral performance of the DSN connections. Representative variables derived from practical midply wood shear walls were considered, including sheathing thickness, nail edge-distance and loading direction to the grain of framing. Test results indicate that the failure modes of the DSN connections depend on sheathing thickness and nail edge-distance. The increase of nail edge-distance and sheathing thickness can significantly improve the ultimate strength and the ductility, while it had little influence on the initial stiffness. Moreover, loading direction to the grain of spruce–pine–fir (SPF) framing had significant influences on the ultimate strength and initial stiffness of DSN connections. Finally, the testing data was idealized to translate the load–displacement behavior of the DSN connections through a typical exponential function model. This study can be used to develop baseline data for the finite-element DSN connection model to predict the performance of midply wood shear walls.

Stochastic Nonlinear Behavior of Reinforced Concrete Frames. I: Experimental Investigation

AbstractThis paper reports a systematic experimental investigation into the stochastic nonlinearities inherent in reinforced concrete (RC) frames. A series of specimen tests is conducted with a static monotonic lateral loading regime. Eight half-scale RC model frames with one story and two spans are designed and constructed in the same condition; specifically, the materials (both concrete and reinforcement bars) used in the frames are derived from the same batch, and the same testing program is performed during the experiments. A newly-designed force transducer is applied in the test to carry out comprehensive measurements of axial force, shear force, and bending moment at the bottom section of each column. Although the physical properties of the frames are apparently the same, test results indicate that the internal forces of the columns show inevitable fluctuations. A conspicuous coupling effect between nonlinearity and randomness, which are inherent in the structure, is exposed. Randomness of materials...

Field tests to investigate the cyclic response of monopiles in sand

Design models for offshore wind turbine monopiles tend to be based on those developed for flexible piles in the offshore oil and gas sectors. However, wind monopiles tend to be shorter and wider, resulting in a stiffer structure that rotates rather than bends when laterally loaded. New methods have been proposed to calculate the load–displacement response of piles to monotonic lateral loading. Those based on correlations with in situ tests such as the cone penetration test seem particularly promising. There is a dearth of experimental test data where monopiles have been subjected to extensive cyclic loading with which to extend such models to consider these effects. To address this, field tests were performed on two 340 mm diameter driven piles with an embedded length of 2·2 m, which were cyclically loaded with up to 5000 loading cycles. The piles had a slenderness ratio (embedded length over diameter) of 6·5, which is a typical value used in the offshore wind sector. The test results show that the accumulated pile head response primarily depends on the soil strength and stiffness, the previous loading history and loading characteristics. A cyclic loading design procedure consisting of cone penetration test based static design and Miner's rule based superposition is presented.

Shear behaviour of masonry walls strengthened by external bonded FRP and TRC

This experimental study focuses on the behaviour of hollow concrete brick masonry walls, especially walls reinforced with composite materials under in-plane loading conditions. This work is a step towards defining reliable seismic strengthening solutions. Indeed, in France, more stringent seismic design requirements for building structures have been considered with the replacement of old design codes. Thus, an experimental program has been performed at the laboratory scale. Six walls have been submitted for shear–compression tests – five walls are reinforced by (1) – fibre-reinforced polymer (FRP) strips using E-glass and carbon fabrics and/or (2) a textile-reinforced concrete (TRC), and the last wall acts as a reference. It is noted that the composite strips are mechanically anchored into the foundations of the walls to improve their efficiency. All of the walls share the same boundary and compressive loading conditions, which are representative of a seismic solicitation. Nevertheless, masonry wall performances and anchor efficiency are only evaluated under monotonic lateral loadings. A comparative study on global behaviour and on local mechanisms is performed and, in particular, highlights that the mechanical anchor systems play an important role in improving the behaviour of reinforced walls (by FRP and TRC) and that the solutions for strengthening by TRC permit the upgrade of the walls’ ductility with a lower strength compared with the solutions with FRP.

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.

Considering the size and strength of beam‐column joints in the design of RC frames

AbstractSome experimental research studies have reported that longitudinal reinforcement in beams and columns exhibits larger strains inside the joint than at the joint periphery (defined as the intersection of the outer surfaces of beam and column). This may explain why several technical specifications and state‐of‐the‐art programs recommend basing the design of beams and columns on internal force values larger than those at the joint periphery. These results and procedures are questionable and are investigated in this paper. The non‐linear finite element analysis presented here for reinforced concrete frames under gravity and quasi‐static monotonic lateral loads examines (i) the stress fields in reinforcement inside interior, exterior and roof exterior joints, and (ii) the load‐carrying capacity of representative sub‐frame models incorporating such joints. The results prove that it is actually safe, with respect to the joint load capacity, to base the design of longitudinal reinforcement in beams and columns on the internal force values at the joint periphery. This result also contributes to the recommendation to use real‐size beam‐column joint models in the analysis procedure.

Impact of CFRP partial bonding on the behaviour of short reinforced concrete wall under monotonic lateral loading

The present research work highlights the significance of partially bonding Carbon Fiber Reinforced Polymer to RC walls to attain reasonable strength and drift without deteriorating wall dissipation capacity. It is worth to mention that no strengthening was applied at the wall edges as in field the wall edges are unexposed as they are mostly connected to columns or walls. Two RC short walls were designed under-reinforced in term of shear and tested to failure under quasi static monotonic lateral loading. One out of these two was strengthened externally with Carbon Fiber Reinforced Polymers (CFRP). The strengthening arrangement consisted of partial bonding of CFRP strips to the wall panel and mesh anchors installation at the wall foundation joint. The reported test results clearly show that the adopted strengthening technique can improve wall performance in terms of strength and deformability with negligible variation in RC wall dissipation capacity. The test result analysis discussion includes cracking pattern, load displacement, deflected shapes, strain distribution in CFRP, and deformability index.

Damage analysis of multi-ribbed wall structures under monotonic lateral loads

Multi-ribbed Wall Structures (MRWS) have been developed in recent years and has been increasingly used in China. However, there is no effective way to quantitatively assess the damage of MRWS subjected to lateral load yet. In this paper, a macro-damage model of MRWS is developed based on the damage theory. First, two types of elements, including fiber rigid frame and bar elements, are introduced to take into account material damage, and local damage index (LDI) is proposed for each type of the elements. Unlike traditional frame element, the innovative fiber rigid frame element can be applied for both axial force and biaxial bending and provides more accurate results. Second, a global damage index (GDI) of structure is derived using the energy theory. Third, the model is implemented in an in-house damage analysis program named MRCS-D, which is further used to experimentally study a MRWS subjected to a combined lateral and vertical loading. There is a good correlation between the numerical and test results. It is shown that the GDI developed in this paper can be effectively used to quantitatively evaluate the damage state and describe the damage progress of the MRWS.

Laboratory testing and finite element simulation of the structural response of an adobe masonry building under horizontal loading

This paper is concerned with the calibration and validation of a numerical modelling approach for adobe masonry buildings under horizontal loading. The paper first reviews the state-of-the-art in experimental and computational research of adobe structures and then presents results obtained from monotonic lateral loading laboratory tests on a 1:2 scaled unreinforced adobe masonry building. Through the experimental investigation conducted, useful conclusions concerning the initiation and propagation of cracking failure are deduced. In addition, damage limit states at different levels of deformation are identified. Experimental results verify that the response of adobe structures to horizontal loads is critically affected by weak bonding between the masonry units and mortar joints and by lack of effective diaphragmatic function at roof level. Based on experimental material data, a 3D finite element (FE) continuum model is developed and calibrated to reproduce the test structure’s force–displacement response and mode of failure. An isotropic damaged plasticity constitutive law is adopted for the numerical simulation of adobe masonry and the use of appropriate modelling parameters is discussed. The FE analyses carried out reveal that the global structural behaviour is primarily influenced by the tensile response assigned to the homogenized masonry medium. Results show that, despite its generic limitations and simplifications, FE continuum macro-modelling can approximate the structural behaviour of horizontally loaded adobe masonry construction with sufficient accuracy. In order to enrich the available information on the seismic behaviour of adobe structures, the calibrated FE model is also subjected to time-history analysis using an accelerogram recorded during a real earthquake.

A Force-Based Equivalent Frame Element for Push-Over Analysis of Masonry Structures

A new macro-element based on the equivalent frame approach is presented to analyze the nonlinear structural response of masonry panels under monotonic lateral loadings. A nonlinear elastic response is assumed for the masonry material and the sectional response of the beam is derived performing analytical integration. A two-node equilibrated force-based (FB) beam finite element (FE) is formulated. The FE is composed of a central flexible part, characterized by a no-tension constitutive relationship, and a lumped nonlinear shear hinge arranged in series, in order to capture the main flexural and shear nonlinear mechanisms characterizing the masonry panel response. Some applications on experimental prototypes are presented, showing a very satisfactory agreement between the numerical results and the experimental outcomes.

Response of skirted suction caissons to monotonic lateral loading in saturated medium sand

Monotonic lateral load model tests were carried out on steel skirted suction caissons embedded in the saturated medium sand to study the bearing capacity. A three-dimensional continuum finite element model was developed with Z_SOIL software. The numerical model was calibrated against experimental results. Soil deformation and earth pressures on skirted caissons were investigated by using the finite element model to extend the model tests. It shows that the “skirted” structure can significantly increase the lateral capacity and limit the deflection, especially suitable for offshore wind turbines, compared with regular suction caissons without the “skirted” at the same load level. In addition, appropriate determination of rotation centers plays a crucial role in calculating the lateral capacity by using the analytical method. It was also found that the rotation center is related to dimensions of skirted suction caissons and loading process, i.e. the rotation center moves upwards with the increase of the “skirted” width and length; moreover, the rotation center moves downwards with the increase of loading and keeps constant when all the sand along the caisson’s wall yields. It is so complex that we cannot simply determine its position like the regular suction caisson commonly with a specified position to the length ratio of the caisson.

Cyclic Pushover Analysis procedure to estimate seismic demands for buildings

Conventional Pushover Analysis relies on the use of monotonic lateral load distribution. The seismic displacement demands based on this procedure are considered an approximate solution that has not taken into account the cyclic loading effects. Under earthquake loading, structural components experience stiffness degradation and strength deterioration, which are the important characteristics of reinforced concrete members under cyclic loading, causing a reduction of deformation capacity. The Cyclic Pushover Procedure is proposed to estimate seismic demands of buildings that take into account the cumulative damage under cyclic loading. The cyclic lateral force distribution is developed based on the mode shapes and the prescribed displacement history. The cyclic pushover curve is converted to the equivalent SDOF pseudo-acceleration and displacement relationship based on the first mode response of the structure. The seismic demands of a 9-story reinforced concrete building are evaluated by Cyclic Pushover Procedure. Four types of loading protocol, i.e., Laboratory, ATC-24, International Organization for Standardization (ISO), and Sequential Phased Displacement (SPD) protocols are employed to investigate the effects of displacement histories on seismic demands. The seismic demands include the peak roof displacement, the peak floor displacement and the peak inter-story drift ratio. The results are compared with the exact demands resulting from nonlinear time history analyses of MDOF structure subjected to 20 ground motions, as well as the demands estimated from the Modal Pushover Analysis. The results demonstrate that the Cyclic Pushover Analysis provides a reasonable and accurate estimate of seismic displacement demands.