High Lateral Loads Research Articles

Effect of Connection Detailing on Reverse Cyclic Behaviour of Precast Beam to Column Grouted Cementitious Billet Connections

In reinforced concrete framed structures exposed to high lateral loads, the performance of the beam to column joints has been acknowledged to have a significant impact on the overall behaviour of the structures. The present study conducted an experimental investigation on four 1/3rd scale Precast Concrete (PC) beam-to-column grouted cementitious billet connections subjected to reverse cyclic loading. Their performance was compared with a reference monolithic connection. The various precast connections studied are Billet with Dowel (BD) connection, Billet with Dowel-cleat Angle (BD-CL) connection, and Extended Billet with Dowel-cleat Angle (EBD-CL) connection. The ultimate load-carrying capacity, ductility factor, hysteretic behaviour, load ratio, energy dissipation, and stiffness degradation of the monolithic (MO) and precast (PC) specimens were studied, and a comparison of their performances was made. The results show that the EBD-CL connection has comparable ductility and strength.

Lubrication Modeling of the Reciprocating Piston with High Lateral Load and Various Conditions in a Swash Plate-Type Piston Pump

Most asymmetrical lateral forces occur in the reciprocating piston mechanism, which is widely applied as a major component of power equipment. When this lateral force greatly acts on the piston, it comes into contact with the cylinder. To prevent this negative phenomenon, lubrication characteristic evaluation and control technology are necessary. In this study, a boundary lubrication model considering the elastic deformation of the contact surface was adopted to perform a lubrication analysis of a piston hydraulic pump widely used in the aviation and plant industries. The piston/cylinder mechanism was analyzed in terms of contact force, characteristic thickness, and power loss while varying various design and operating parameters (friction coefficient, clearance, profiling shape, operating speed, and pressure). In the overall bearing capacity to withstand the tilt of the piston, the bearing capacity ratio due to contact at the interface increased more steeply than the bearing capacity ratio in the fluid lubrication area. Profiling of the piston head played a positive role in reducing power loss but also increased piston tilt. This trend appeared more clearly as the head profiling degree of processing Increased. Lastly, the effects of variable operating speed and pressure were examined. High operating speed caused low contact force, and high operating pressure caused high contact force. Through this study, it was possible to predict the lubrication performance and power loss of reciprocating piston pumps used in the field more realistically through appropriate boundary lubrication modeling.

Assessment of Bullet Impact and Failure Mechanism of Concrete Containing Polythene Aggregates

The time from the initial stage of existence on Earth, the war continued. In this concern, India’s DRDO (Defence Research and Development Organization) and OFB (Ordnance Factory Board) worked appreciatively to develop new protective gear against assault weapons. The main focus of bullet or blast proof structures is to safeguard the life of soldiers, their accessories and gears, along with confidential and classified acquittance, firearm and ammunition, and sensitive systems. Defence structures like bunkers and tranches were designed in such discipline to keep them active round-the-clock with heavy armoury and made functional near to Line of Control (LOC) and Line of Actual Control (LAC) which oppose the effect of highly intensive blast waves. In such a manner, field testing with different Indian assault rifles i.e. INSAS (Indian Small Arms System), SIG 716i (US origin), and INSAS LMG (Indian Small Arms System-Light Machine Gun) was made from different ranges starting from 50mts to 300 mts extreme. Such structures were designed to protect the safety of soldiers from the bump of bullet effect. Structures designed are very strong and durable with opposition to high lateral load and visible surfacing. Construction material used for building plays a foremost role. The investigation is based on unique and advanced ideas in designing the defence structures. The investigation elaborates on the difference between conventional designing and the special designing of defence structures, as the advanced concept of polythene aggregates performs better than ordinary concrete.

Centrifuge testing of improved monopile foundation for offshore wind turbines

Large fixed vertical offshore wind turbine (OWT) tower structures are typically used to transfer complex loads to the foundations from a combination of wind, waves, and self-weight. These loads must be accommodated within a very small rotation envelope and natural frequency bands to allow the turbines to operate effectively. These challenging loading conditions and strict operational requirements can lead to extremely costly foundation designs. Several foundation options are available to support these turbines, with monopiles currently accounting for 80% of the installed capacity with routinely used diameters of 5–8 m and depths of penetration of 30–80 m. To limit monopile diameters and penetration depths, an improved monopile design: the ‘hybrid foundation’ comprising a plate and centrally located pile, is proposed as an alternative to monopiles. A series of scaled physical model centrifuge tests were conducted to investigate the benefits of the hybrid foundation system and compare its behavior with the typically used monopiles. This type of foundation system can enhance the performance of an OWT since the turbines are subjected to high lateral loads and overturning moments. Centrifuge modeling has been used to investigate the lateral capacity and stiffness of the foundations under lateral monotonic and cyclic loading conditions. Two models were tested: a standard monopile (MP) and a hybrid foundation (HF). Lateral loads were applied with eccentricity for both models to replicate prototype (field) conditions. Models were tested at 50g in over-consolidated clay beds. These soil samples were prepared using inflight consolidation and subjected to a sand surcharge, to increase the shear strength in the zone of influence of the model foundations. Monotonic lateral loading results indicated that the addition of a plate improves the relative lateral ultimate capacity, whilst enabling a reduction of monopile penetration depth and diameter for similar capacities. Specifically, similar capacity/stiffness was realized for the HF system compared to the MP. One-way cyclic lateral loading indicated both the HF and the MP had a shakedown response under fatigue loading of up to 10000 cycles, which indicates the potential use of this novel system for future developments.

Lateral behavior of monopiles under the simultaneous effect of vertical-lateral loads and change of embedment depth due to 1D local scouring

Offshore wind turbine foundations are subjected to high lateral loads but insignificant vertical forces of the superstructure. A decrease in the embedment depth due to scouring can also alter the effect of vertical loads on the soil-structure interaction. Current design methods consider the vertical and lateral forces in design separately. This area also lacks studies featuring physical modeling that produce consistent conclusions. The present study employed centrifugal physical modeling to investigate the lateral behavior of offshore wind turbine monopiles under the simultaneous effects of vertical and lateral loads with a change in embedment depth caused by 1D local scour (D = diameter of pipe) in calcareous sand. The results showed that the vertical load of the superstructure increased the lateral strength of the monopile in the no-scour and local scour cases by about 3.5% and 6%, respectively. Improvements in the p-y curves along the embedment depth were noted at depths of less than twice the monopile diameter. Stress intensification was more significant under the scoured conditions because of the reduced embedment depth of the monopile. Overall, the vertical superstructure loads had little effect on the lateral performance of the monopiles.

A Review on Effect of the Positioning of Shear Wall for Earthquake Resistance Multi-Story Building

Earthquake is one of the major natural disasters in the world. It considered that. The damage caused due to the collapse of buildings during the earthquake is huge. The main reason for this calamity is the extirpation of manmade structures. The structure’s lack of lateral rigidity is the first reason for its destruction during an earthquake. multi-story buildings need a seismic motion for their stability. Some endeavors have been done for finding the best method to make multi-story buildings strong and stable against earthquake forces. Provision of shear wall is one of the main options to provide diaphragm, which provides lateral strength for high-rise and multi-story structures. Shear walls have proper characteristics such as stiffness and strength, which can support building to resist high lateral and vertical loads. This paper aimed to find out the optimum positioning of the shear wall in a multi-story building on the sloped ground. A reinforced concrete (RC) framed building of (G+5) story on sloping area subjected to earthquake loading in zone V is considered. The analyses and design comparison is carried out using STAAD Pro structural design software. Different cases of the shear wall at various locations of the considered building have been analyzed.

Dynamic Soil Structure Interaction of a High-Rise Building Resting over a Finned Pile Mat

High-rise building safety is generally supported by pile-mat systems. They must be sturdy enough to withstand potential lateral loads brought on by earthquakes, wind, dredging, and machine vibrations, in addition to increased axial loads. An innovative piled-mat foundation system is required to deal with these impacts because standard pile foundation systems only have lateral capacities that are 10% of their axial capacities. This study aims to reduce the damage caused by seismic impacts on high-rise buildings using shear walls supported by piled mats, thereby minimizing vibrations within the structure. Compared with conventional pile systems, the finned-pile foundation is a proven method that can withstand a 65% to 80% higher lateral load; hence, a series of SSI analyses were performed on a 25-story high-rise building, with the shear wall resting on a finned-pile mat (FP-Mat), under a far-field earthquake excitation, using ABAQUS software. The seismic responses were studied by performing a time–history analysis on the FP-Mat, with varying fin-lengths (Lf) of 0.2Lp, 0.4Lp, 0.6Lp, and 0.8Lp, which was compared with an analysis of a conventional piled-mat (RP-Mat). The seismic responses for RP-Mat and FP-Mats were studied with peak-acceleration, maximum horizontal displacement, and inter-story drifts acting as the damage parameters. The provision of FP-Mats significantly reduced the vibrations and seismic effects on the building, and as the fin-length increased, the vibrations and seismic effects reduced further. The drifting bound was also reduced as the fin-length increased. The optimum fin-length for FP-Mats is suggested to be 0.6Lp in terms of seismic performance and construction efficiency. This study helps one understand the seismic behaviors of high-rise buildings resting on finned pile mats.

Experimental and Numerical Investigation of the Cross-Sectional Mechanical Behavior of a Steel–Concrete Immersed Tube Tunnel

This paper presents a proposed static test and numerical study on the mechanical properties of steel-shell–concrete-structure-immersed tunnel nodes, which is used to investigate the seismic performance and damage mechanism of steel-shell–concrete-structure-immersed tunnel nodes. The test is based on the immersed tube tunnel project in the deep China channel, and the nodes representing the outermost and innermost vertical walls of the immersed tube tunnel, i.e., L-shaped and T-shaped node specimens, were designed and fabricated at a scale of 1:5, and the specimens were mainly subjected to the combined effect of vertical axial compression and lateral displacement loads. The test results show that the L-shaped node will exhibit brittle damage characteristics with high lateral load carrying capacity and energy dissipation capacity during the ultimate load phase, while the T-shaped node exhibits bending damage with better ductility, so the outermost vertical wall should be locally reinforced to ensure the necessary ductility of the structure in the actual project. In addition, by comparing the numerical calculation and experimental results, it is found that there is good agreement in terms of load–displacement curves and crack distribution, which shows that the modeling method proposed in this paper can accurately simulate the mechanical properties of immersed tunnel nodes and can guide the section design of immersed tunnels with steel shell–concrete structures.

Diagrid Based Multistorey Building Design and Durability Forecasting

Abstract: The taller and higher structures results in the effects of lateral loading, lateral loads dominates when the height of building increases, lateral loads such as earthquake, wind causes the building larger displacement, to avoid larger displacement in high rise buildings lateral load resisting systems are deployed. Apart from other structural system, the diagrid and hexagrid system are adopted to improve structural performance of tall buildings. The various types of structural system in tall buildings have become obsolete and the new structural skeletons such as hexagrid and diagrid are being used

Performance of high-rise pile group adjacent slope

For the consideration of required elevation, pile shafts are partially buried in the soil stratum and partially exposed above the ground surface, known as high-rise pile group (HRPG). The HRPG is extensively used in the construction of infrastructures and is usually adjacent the slope. It is frequently subjected to high lateral loads from the superstructure, leading to considerable displacement and bending moment. To alleviate the deformation and internal force of HRPG, a batter pile is employed, forming the high-rise batter pile group (HRBPG). A numerical simulation is conducted to observe the response of HRPG foundation subjected to downwards lateral load adjacent slope. The effects of slope angle, cap elevation, and lateral loading magnitude are determined. Results of HRBPG are compared with traditional high-rise vertical pile group (HRVPG). Conclusions can be drawn as follows. (1) The slope has significant effect on the displacement and bending moment of HRPG, so it should be considered in the design process. The displacement and bending moment of pile shaft increase gradually with the slope angle (0°–30°) and then they have a sharp growth (45°–60°). (2) With the rise of cap elevation, the displacement increases dramatically, whereas the bending moment rises and then falls. The displacement is highly sensitive under lateral loading with a high cap elevation; the higher the elevation is, the greater the displacement will be. Special attention should be paid when a high pile cap is adopted under large lateral loading. The displacement and bending moment of HRBPG are considerably smaller than those of HRVPG at a high pile cap elevation. (3) The displacement and bending moment are relatively small when a diminutive lateral loading is performed; however, they have a sharp growth under large lateral loading. The larger the load is, the greater the bending moment and displacement will be. (4) The displacement of the leading pile is slightly larger than that of the trailing pile, whereas the bending moment of the rear pile is larger than that of the leading pile. The pile shaft displacement above the ground surface is considerably larger than that below. The maximum bending moment occurs at the pile head, and the pile toe has minuscule bending moment. (5) The use of batter pile is beneficial for reducing the displacement and bending moment, whereas the slope and lateral loading are detrimental.

A Comparative Study of Vertical and Batter Piles under Lateral Loading Conditions: A Review

Laterally loaded piles are generally used where high lateral load acts on the structures. Vertical piles along with batter piles are used in structures such as chimneys, towers, dock and harbor structures, and high-rise buildings. Various techniques have been used in literature to solve the laterally loaded pile problems. Among them p-y method is preferred over all other methods. Various researchers have provided analytical solutions for vertical and batter pile problems and are discussed in this paper. Experimental investigations were also carried out by various researchers on vertical and batter piles, indicating that the negative batter piles offer large resistance to lateral loads when compared with the vertical piles. The deflection values obtained from the analytical solutions were also compared with the model tests and were found to be in a good agreement. Numerical modeling conducted by various researchers on vertical and batter pile foundation by various researchers is also discussed in this paper.

Effect of Bay Spacing on Design Parameters of RC Structures Subjected to Lateral Loads

Structural configuration is one of the important parameters to control the performance of multi-storeyed structures subjected to lateral loads. On other hand, also the economy of multi-storeyed structures depends on the spacing of columns. The present investigation is aiming to find the effect of bay spacing on the performance of medium to high rise RC structures subjected to lateral loads. In this regard, a computer- based analysis is carried out for 10, 15, 20, 25 and 30 storied bare frame structures. Each structure performance under lateral loads is investigated for 4 types of bay spacing i.e. 5m, 6m, 7.2m and 8.64m, with an increment of 20% bay space each time. For each structural model, the behaviour of the structure is examined in terms of storey displacement, storey drift and base shear. The quantitative parametric comparison is done between all the models mentioned and has identified the optimal size of the bay spacing to suit the aspect ratio of the structure is proposed.

Seismic behavior of high-strength concrete-filled square steel tube columns reinforced with ultrahigh-strength reinforcing bars

This paper investigated the seismic behavior of high-strength concrete-filled square steel tube columns reinforced with ultrahigh-strength reinforcing bars. Three full-scale specimens with different amounts of ultrahigh-strength longitudinal reinforcing bars under a high axial load ratio and cyclic lateral load were tested. The test results demonstrate that the existence of ultrahigh-strength longitudinal reinforcing bars had a significant influence on the seismic behavior of high-strength concrete-filled steel tube columns. Compared with conventional concrete-filled steel tube (CFT) columns, the deformation capacity, bearing capacity and cumulative energy dissipation of these innovative CFT columns are greatly improved, and the cumulative damage and plastic deformation of the specimens decreased with the introduction of steel bars. A calculation model based on AISC360-16 using the superposition method was proposed and verified to evaluate the compressive-flexural strength of the specimen.

P-y Curves of laterally loaded barrettes

Rectangular shaped piles (barrettes) are extensively used in construction projects to resist relatively high lateral loads in different onshore and offshore facilities. The need to analyze barrettes subjected to lateral loads is one of the challenges in the field of deep foundations. P-y curves and finite element method are widely trusted approaches to depict the behavior of such embedded concrete elements under the effect of lateral loads. In this paper, the authors aim to introduce a comprehensive approach to use validated numerical models to create the P-y curves that can be easily used to design laterally loaded barrettes. The performed analysis in this study focuses on developing P-y curves for cohesionless soil formations. The developed P-y curves from the analyses are compared to the P-y curves generated using the formulae of Reese, 1974, and API, 1993 for cohesionless soils. International standards and codes of reinforced concrete structural elements recommend considering the concrete cracking effect in the numerical analysis by reducing the flexural stiffness by an average value of 50% of that of the intact elements. Laterally loaded barrettes with different dimensions are analyzed in this study, using the finite element method to generate the corresponding P-y curves. Comparison between the P-y curves of laterally loaded barrettes of different dimensions and their corresponding piles of equivalent perimeters and areas, as well as piles of a diameter equal to the corresponding barrettes’ width, is performed through this paper. Results of the performed analyses show that P-y curves of rectangular barrettes under lateral loads are relatively similar to that of piles with an equivalent perimeter.

Seismic behaviour of concrete bridge piers with various types of transverse reinforcement

Past bridge failures due to earthquakes have been found to be due to inadequate seismic design of the bridge piers. It is thus essential to investigate the effect of lateral confinement on the seismic behaviour of bridge piers. The aim of this study was to evaluate, experimentally and numerically, the seismic performance of reinforced concrete bridge piers with various types of transverse reinforcement. For this purpose, three scaled-down (1 : 4) circular bridge pier specimens were tested under constant axial and quasi-static cyclic loading (QSCL). A control specimen was made with spiral lateral reinforcement, while the other two specimens were made with stirrups with cross-ties and strips with cross-ties. The hysteresis loops, envelope curves, energy dissipation and stiffness degradation of all three specimens were determined in order to evaluate their seismic behaviour. Compared with the control specimen, the specimen with strips and cross-ties showed increased lateral load capacity, cumulative energy dissipation and higher initial stiffness due to the effect of increased confinement. The results of finite-element analysis showed good agreement with the experimental results. The findings of this study indicate that strips with cross-ties can be used in bridge piers when a high lateral load carrying capacity and energy dissipation are required.

Seismic performance of reinforced concrete interior beam-column joints with novel reinforcement detail

Horizontal stirrups are normally required in reinforced concrete (RC) beam-column joints (BCJs) for resisting shear forces in seismic design. For RC moment-resisting frames subjected to a high lateral load, a large number of stirrups are needed in joint cores. This may cause reinforcement congestion, leading to construction difficulty and insufficient concrete compaction, which can result in poor seismic performance. In this study, a novel reinforcement detail in the form of unbonded diagonal bars mechanically anchored at beam ends is proposed for RC interior BCJs. The detail alleviates the reinforcement congestion through partially replacing horizontal stirrups, and improves the seismic performance of BCJs by plastic hinge relocation and input shear force reduction mechanisms. Four 2/3-scale RC interior BCJ specimens were prepared and tested under quasi-static cyclic load, including one specimen designed with the current code and three specimens adopting the proposed reinforcement detail. Test results show that the proposed reinforcement detail is able to relocate the plastic hinges away from beam-joint interfaces as well as improve the loading capacity, energy dissipation capacity, stiffness, and bonding condition of beam reinforcements within the cores of BCJs. The combined use of stirrups and the proposed reinforcement detail significantly enhances the cracking resistance and reduces joint distortion, while additional amount of stirrups results in a marginal improvement. Moreover, an analytical model considering plastic hinge relocation and input joint shear force reduction is proposed for BCJs with the novel reinforcement detail. The model can adequately predict the failure mode and loading capacity of BCJ specimens.

Seismic strengthening of improperly repaired reinforced concrete columns using CFRP confinement

In this study, lack of strength, stiffness, energy dissipation and ductility characteristics of the improperly repaired RC square columns were examined and the recoverability of seismic performance with the external Carbon Fiber Reinforced Polymer (CFRP) confinement was investigated. A total of six RC columns were tested for three times with different test stages; as-built, improperly repaired with Normal Strength Concrete (NSC) and retrofitted with CFRP confinement. In the first tests, relatively high axial load (0.40Acfc) and cyclic lateral load up to 15% lateral strength loss were applied to expose heavy damage on test columns. After that, the damaged columns repaired by using NSC and retested under the same loading conditions. In the first two test stages, the drift ratio at the end of tests was approximately 5%. The lateral strength, stiffness, ductility and energy dissipation characteristics of the improperly repaired columns dramatically decreased. At the last stage tests, the stiffness of strengthened columns was considerably reduced due to the damage that occurred in the concrete core after the two pre-damage phases. The lateral strengths of the CFRP retrofitted columns did not change much compared to the as-built columns because of the quality of the repairing concrete (26 MPa and 54 MPa) and the strain hardening behavior of steel reinforcement. Compared to the as-built columns, the cumulative energy dissipation capacities of columns were significantly increased, however, ductility increase was not achieved for all specimens because of the dramatic loss of stiffness.

Shear Wall Design within the Light of Prominent Standards

Reinforced concrete (RC) structures have their own weight, earthquake, wind, dead loads, live loads, creep, etc. throughout their service life. They are exposed to internal and external load effects. In order to meet the horizontal forces such as earthquake and wind from these loads affecting the structure, shear wall structures with high lateral rigidity are needed. Therefore, shear walls are one of the most important structural elements that can resist earthquake forces due to their high lateral rigidity and load bearing capacities. Most of the buildings today are designed according to the old regulations. Therefore, the shear wall was sized and reinforced according to these old regulations. However, to date, standards have been renewed in certain periods. Despite this, shear walls designed according to the old regulations continue to resist seismic forces. In this study, the design and behavioral differences of the reinforced concrete shear walls between the Turkish Regulation that came into force in 2019, and the old regulation were compared. In addition, RC shear walls were evaluated according to ACI-318-19 and EuroCode-2 regulations.

Experimental behaviour and failure of beam-column joints with plain bars, low-strength concrete and different anchorage details

In framed structures, both steel and reinforced concrete, beam-column joints play a very crucial role in terms of seismic resistance. Under the effects of high lateral seismic loads, beam-column joints are subjected to high forces and moments and their behaviour have a significant influence on the response of the structure. Poor seismic performance of inadequately detailed joints can lead to the total or partial collapse of reinforced concrete frame structures. The use of low strength concrete, plain reinforcing bars, problematic anchorage details and inadequate transverse reinforcement in beam-column joints are the factors increasing the failure risk of the structures during severe earthquakes. In this paper, an experimental study on the cyclic behaviour of reinforced concrete exterior beam-column joints is presented. The study aims at investigating the effects of the longitudinal beam reinforcement anchorage detail on the joint performance and quantifying the level of contribution of retrofitting the joints by fiber reinforced polymer sheets (FRP). Three different details were considered in the test program including the longitudinal reinforcement of the beam being anchored within the joint with 90-degree hooks, 180-degree hooks and straight bar (no hook). All of the test specimens were produced using low strength concrete and plain bars to represent the conditions of joints of existing deficient reinforced concrete building structures. In the first series of tests, four 2/3 scale reinforced concrete beam-column joint specimens were tested by adopting a displacement controlled and quasi-static load application method to assess the performance of joints with the above-mentioned anchorage details. The load was applied in a reversed cyclic fashion. The second series of tests were carried out on two additional specimens with the same details as described above but strengthened using FRP sheets. The response of the specimens were evaluated and compared in terms of load-drift, displacement hysteretic behaviour. It was found out that the problematic anchorage details have a very significant adverse effect on the seismic performance of the joints. On the other hand, FRP retrofitting has resulted in a significant increase in peak loads and sustained ductility particularly for the specimens for which reinforcement slippage was not a governing mode of failure.

Seismic behavior of large-scale FRP-recycled aggregate concrete-steel columns with shear connectors

The application of fiber-reinforced polymer (FRP) composites for the development of high-performance composite structural systems has received significant recent research attention. A composite of FRP-recycled aggregate concrete (RAC)-steel column (FRSC), consisting of an outer FRP tube, an inner steel tube and annular RAC filled between two tubes, is proposed herein to facilitate green disposal of demolished concrete and to improve the ductility of concrete columns for earthquake resistance. To better understand the seismic behavior of FRSCs, quasi-static tests of large-scale basalt FRSCs with shear connectors were conducted. The influence of the recycled coarse aggregate (RCA) replacement percentage, shear connectors and axial loading method on the lateral load and deformation capacity, energy dissipation and cumulative damage were analyzed to evaluate the seismic behavior of FRSCs. The test results show that FRSCs have good seismic behavior, which was evidenced by high lateral loads, excellent ductility and energy dissipation capacity, indicating RAC is applicable in FRSCs. Shear connectors can significantly postpone the steel buckling and increase the lateral loads of FRSCs, but weaken the deformation capacity and energy dissipation performance.