Effect Of Lateral Loads Research Articles

Analytical Study on Effect of Geometry of Tall Buildings on Diagrid Structural Systems Subjected to Lateral Loads

Structural design of high rise buildings is governed by lateral loads due to wind or earthquake. As the height of building increases, the lateral load resisting system becomes more important than the structural system that resists the gravitational loads. Recently, diagrid structural system are widely used for tall buildings due to its structural efficiency and flexibility in architectural planning. Diagrid structural system is made around the perimeter of building in the form of a triangulated truss system by intersecting the diagonal and horizontal members. Diagonal members in diagrid structural systems can carry gravity loads as well as lateral loads. Lateral loads are resisted by axial action of the diagonals compared to bending of vertical columns in framed tube structure. The structural efficiency of diagrid system also helps in avoiding interior and corner columns, thereby allowing significant flexibility with the floor plan. In this paper, effect of lateral loads on steel diagrid buildings are studied. Square and rectangular buildings of same plan area with diagrid structural system is considered for the study. Diagrid modules extending upto 2,4,6,8 and 12 storeys are evaluated. Static analysis for the gravity loads, wind and earthquake and response spectrum analysis are carried out for these different combinations of plan shape and diagrid modules and performance of all these diagrid models i.e., storey displacement, storey drift and modal time period are evaluated and compared in this study.

Structural behavior of strengthening masonry in-filled frames subjected to lateral load using bonded and un-bonded CFRP

Lateral loads annually destroy many reinforced concrete structures in different countries. However, there is a necessary need to retrofit masonry infill walls to utilize them as lateral load resisting elements. For this purpose, an experimental program has been carried out on half scale specimens to characterize the behavior of single story brick masonry in-filled frames under the effect of lateral loads. The effectiveness of different strengthening techniques is investigated using Carbon–fiber Reinforcement Polymer (CFRP). The steel reinforcement at the beam-columns joints of all specimens was detailed as hinged connection. FRP sheets and FRP strips were used as strengthening agents for the tested specimens. They were utilized in two different cases, bonded or unbonded to the masonry wall. In addition, the FRP anchor technique was used to increase the efficiency of bonding the strengthening agents with the frames and the walls. The load–displacement behavior, FRP strain, crack pattern, steel strain, and mode of failure of the tested specimens were investigated. The results showed that the used strengthening methods are effective, with high increase in strength and ductility. In addition, an analytical model was presented and solved. Based on this model, simplified empirical equation to design the required amount of FRP needed to resist lateral loads was proposed. The equation showed a good agreement with both the experimental result and finite element output.

Influence of interface on the behavior of infilled frame subjected to lateral load using linear analysis

Two dimensional numerical investigations were carried out to study the influence of interface thickness and their pattern on the behavior of reinforced concrete frames subjected to in-plane lateral loads using commercial finite element tool SAP 2000. The linear elastic analysis was carried out on one and two bay structural systems as well as the influence of number of stories was studied by varying the number of stories as single, three and five. The cement mortar was used as interface material and their effect was studied by varying thicknesses as 6, 8, 10, 14 and 20 mm. The interface was recognized as one sided, two sided, three sided and four sided and their effect was studied by removing the interface material between the reinforced concrete frame and masonry infill. The effect of lateral loads on infill masonry wall was also studied by varying assumed loads as 10, 20, 30, 40, 50 and 60 kN. The behavior of infilled frames studied has revealed that there is a maximum influence of interface thickness and interface pattern corresponding to 10 mm thickness. In general, the lateral displacement of frame is increased linearly with increase in lateral loads.

Comparative Study on Wind Analysis of Multi-story RCC and Composite Structure for Different Plan Configuration

The multi story high rise RCC structures are more bulky and less ductile in nature as compare to composite structures. This study investigates the comparison between RCC and composite structure under the effect of wind, additional to it composite structure also includes different plan configurations. In this study total fifteen number of building model are prepared and analysis for wind load by using ETABS 2015. The wind analysis is performed for different heights such 20m, 50m and 80m. In addition, the comparative study concludes that the composite structure are larger ductile in nature and more susceptible as compare to RCC structure and the composite option is better than RCC for multi story buildings. In addition, the comparison of different plan configuration shows that the response of parameter such as story displacement, story stiffness, base reaction and time period under effect of wind. The purpose of this analysis is to determine the most effective shape of structure in prone zone. The reinforced concrete structures are mostly used from many decades because of its stiffness, most convenience, high durability and ease to construct. The RCC structures are more suitable for low rise structure but for medium to high rise structures it is no longer economical because of large dead load, less susceptible, span restriction and complex formwork. So that, Structural designer is facing the problem of less susceptibility to lateral loads and also the problem of economy. The population of India is increasing day by day and they required land for living, for that multi story structures are best option for construction in metropolis cities where less land is available. Because multi story structure provides large floor area in small land area. Therefore, it is essential to construct high rise buildings. If high rise buildings are constructed than many structural problems arise, such as lateral load effect, lateral displacement and stiffness etc. Generally for high rise structure wind and earth quake load effects are dominant. Therefore for high rise buildings it is essential to have knowledge of various loads and its effect on buildings. The effect of lateral load is very important to consider such as earthquake and wind loads. In some cases the wind load is dominant than earthquake load which depends on area and zone factor defined by codes. Defining wind there are two aspects first one is beneficial which is to generate power and gives relief in hot and humid atmosphere and second one is parasitic which comes out to be factor consider for engineers. This wind effect will cause and produce wind induced motion in the structure. As high rise buildings push the envelope to greater heights, the structural designers are not only faced with problem to choosing a structural elements to carry the lateral load such as wind load and earthquake load but also insuring the design criteria that meets stability and serviceability requirement under complex wind environment. In addition, the high rise structures should meet more stiffness under lateral loads. Wind load act as lateral load on buildings which is act as along and across wind. In IS Code 875(Part 3)-1987, the basic wind speed are given in map and categorized by zones. The shape of buildings is very important in wind analysis, because the wind pressure is mainly depends on the exposed area of building against wind.

HEALTH MONITORING ANAYLSES OF CRACKED PLATES BASED ON FORCED VIBRATION

This research presents a SHM (Structural Health Monitoring) techniques that are based on harmonic and transient analyses of cracked plate structure. Finite element models for the different cracked steel plate have been created by considering the length and the orientations of the crack, and a cantilever supported plates (parallel to the crack) are used. The cracked structures are examined under harmonic concentrated lateral load. The frequency responses show that the lateral deflections of the crack plate decrease when increasing the crack length, whereas, the lateral deflections increase when increasing orientation angle until 90°. The models are also examined under the effect of transient concentrated lateral load. The time history responses show that the lateral deflections of the crack increase when increasing the crack length. Finally, SHM analysis is applied in order to predict the early behaviour of the plates in accordance with the results above. The extrapolation for certain symbols of the results is performed to derive numerical formulas of the lateral deflections .The lateral deflection’s formula is used as a function for the half-crack length, however, there is a formula for each orientation angle.

3D finite element modeling of bond-controlled behavior of steel and basalt FRP-reinforced concrete square bridge columns under lateral loading

Bond between reinforcing bars and concrete plays an important role in controlling the structural performance of reinforced concrete (RC) structures. The main objective of this study was to create and execute a detailed three dimensional (3D) finite element (FE) model evaluating the structural performance of fiber reinforced polymer (FRP)-steel RC (FSRC) bridge columns and considering the effect of several bond conditions between FRP bars and concrete. Hence, bond behavior of basalt FRP (BFRP) bars with different surface conditions was firstly discussed in comparison with ribbed steel bars. After that, results of the created 3D FE models for FSRC columns reinforced with BFRP bars having different bond conditions were validated in the light of results of four columns experimentally tested under the combined effect of constant axial load and cyclic lateral loading. Ultimately, a parametric study was conducted to find out the effect of different bond conditions of FRP bars on the structural performance of FSRC columns. The numerical results showed that response of FSRC columns to lateral loading is dependent on bond conditions between FRP bars and the surrounding concrete: characteristics of bond–slip relationship of FRP bars could be adopted as design parameters controlling the behavior of FSRC columns. Failure mode, lateral strength, post-yield stiffness ratio, ductility at the peak lateral strength and at failure are all depend on the bond parameters of FRP bars. However, FRP bond parameters did not show a pronounced impact on the column elastic stiffness.

Numerical Simulation to Study the Effect of Combination Vertical Load and Lateral Load on Pile Performance in Cohesionless Soil

Pile foundation is widely subjected to both vertical and lateral loads. The available design procedure assumes that the effect of these two loads is independent of each other and hence the pile design is carried out separately for vertical and lateral loads. The traditional methods for analysis of piles according to sub-grade reaction methods also do not consider the effect of interaction between the different load directions. The effect of combination vertical loads and lateral on pile performance that installed in cohesionlesssoils is considered in this paper through three-dimensional finite element analyses. In the numerical model, the pile was treated as a linear elastic material and the soil was idealized using the Mohr-Coloumb constitutive model. The results from the analysis of single piles under combined vertical and lateral loads are studied in this paper. The influences of related parameters such as shear strength (angle of internal friction and dilatation angle) of soil in term of loose and dense sands and pile/soil interface friction coefficient have also been studied in this work.The results have shown that the combination vertical load and lateral has a significant effect on the pile performance that installed in cohesionless soil.

EFFECT OF THE GRAIN SLIDING ON THE SEISMIC BEHAVIOR OF CIRCULAR SILOS: A THEORETICAL FORMULATION

Earthquakes frequently cause damage or collapse in silos, provoking significant financial loss and even loss of life. The effect of lateral seismic loads can damage the upper portion of the silo if the material contained can oscillate inside the silo during the ground motion. The contribution of the grain sliding in terms of wall stresses is not explicitly accounted neither in current design codes nor in scientific literature. In the present paper, the effect of the horizontal sliding of the grain layers is accounted in terms of additional overpressures, wall shear and bending moment during dynamic excitation and compared with theoretical formulations, code provisions and experimental evidence. Shaking table tests suggest that the grain sliding may be relevant in the evaluation of the wall base bending moment and that ACI 313-97 and Eurocode 8 provisions appear overly conservative. Finally, a design recommendation is drawn for reducing the effect of the seismic actions on the silo wall.

Retrofitting of vulnerable RC structures by base isolation technique

The scale and nature of the recent earthquakes in the world and the related earthquake disaster index coerce the concerned community to become anxious about it. Therefore, it is crucial that seismic lateral load effect will be appropriately considered in structural design. Application of seismic isolation system stands as a consistent alternative against this hazard. The objective of the study is to evaluate the structural and economic feasibility of reinforced concrete (RC) buildings with base isolation located in medium risk seismic region. Linear and nonlinear dynamic analyses as well as linear static analysis under site-specific bi-directional seismic excitation have been carried out for both fixed based (FB) and base isolated (BI) buildings in the present study. The superstructure and base of buildings are modeled in a 3D finite element model by consistent mass approach having six degrees of freedom at each node. The floor slabs are simulated as rigid diaphragms. Lead rubber bearing (LRB) and High damping rubber bearing (HDRB) are used as isolation device. Change of structural behaviors and savings in construction costing are evaluated. The study shows that for low to medium rise buildings, isolators can reduce muscular amount of base shears, base moments and floor accelerations for building at soft to medium stiff soil. Allowable higher horizontal displacement induces structural flexibility. Though incorporating isolator increases the outlay, overall structural cost may be reduced. The application of base isolation system confirms a potential to be used as a viable solution in economic building design.

Pushover analysis of gabled frames with semi-rigid connections

The nonlinear static analysis of structure, which is under the effect of lateral loads and provides the capacity curve of the structure, is defined as a push-over analysis. Ordinarily, by using base shear and the lateral displacement of target point, the capacity curve is obtained. The speed and ease of results interpretation in this method is more than that of the NRHA responses. In this study, the nonlinear static analysis is applied on the semi-rigid steel gabled frames. It should be noted that the members of this structure are analyzed as a prismatic beam-column element in two states of semi-rigid connections and supports. The gabled frame is modeled in the OpenSees software and analyzed based on the displacement control at the target point. The lateral displacement results, calculated in the top level of columns, are reported. Furthermore, responses of the structure are obtained for various support conditions and the rigidity of nodal connections. Ultimately, the effect of semi-rigid connections and supports on the capacity and the performance point of the structure are presented in separated graphs.

健全時および損傷後の船体縦曲げ最終強度に関する一研究

In order to examine the effect of initial imperfections and lateral loads on the hull girder ultimate strength of intact and damaged hull structures, a series of nonlinear calculation is performed using finite element (FE) analysis code, LS-DYNA. In addition, the hull girder ultimate strength of intact and damaged hull structures is calculated utilizing the simplified calculation program, which is developed by the authors and based on the Smith’s method, and the reduction ratio of hull girder ultimate strength is also investigated. Furthermore, to examine the accuracy of this simplified calculation program, calculation results are compared with results obtained by FE analyses.

Finite Element Assessment of Methods for Incorporating Axial Load Effects into Blast Design SDOF Analyses of Precast Wall Panels

AbstractInnovations in the U.S. construction and precast concrete manufacturing industries have resulted in efficient methods of constructing multistory buildings that are entirely supported by precast concrete walls (i.e., no structural frame). Simultaneously, the U.S. government has mandated overarching requirements and incentives that promote energy efficiency in all government buildings and facilities. The combination of construction efficiencies and relatively recent requirements for improving energy efficiency makes total precast construction an attractive option for constructing government, diplomatic and U.S. Department of Defense (DoD) buildings and facilities. However, to design load bearing wall panels for DoD blast response criteria, engineers need a relatively simple method for analyzing dynamic response under combined lateral and axial load effects. This paper presents methods for incorporating the P-delta and P-M interaction effects into the single-degree-of-freedom (SDOF) framework that is...

ANALYSIS AND CONNECTION DESIGNS OF PRECAST LOAD BEARING WALL

Lateral load on a multistory building is most critical one to consider for the design. In order to observe the seismic effect and wind effect on multi-story building, a study on precast load bearing wall of G+11 has been carried out. Four different seismic zones and all wind zones are considered for analysis using ETABS. The structural response due to lateral loads with load combination is extracted. Effect of lateral load on out-of-plane moments, axial forces, shear force, base shear, maximum storey drift and tensile forces on shear wall are plotted. Finally the effect of seismic zone and wind zone is tabulated.

SEISMIC PERFORMANCE OF FRICTION PENDULUM BEARING BY CONSIDERING STOREY DRIFT AND LATERAL DISPLACEMENT

Base Isolation technique is used to decouple the base from its superstructure during the ground motions caused by earthquake. The present study is done on a G+4 storey building, considering three models where the first model indicates the bare frame structure, second model indicates the with infill structure which is modelled as equivalent diagonal strut and the third model indicates the base isolated structure using friction pendulum bearing. The main objective is to study the dynamic response of with infill and without infill structure and carrying design of FPS for the maximum response of structure such as lateral displacement and storey drift. The dynamic analysis of with infill and without infill structure indicated that the structure is stiffer with infill effect and structural response also get reduces. The base isolated structure reduces the inter storey drift and lateral load effects on the structure.

Lateral Pile Analysis Frozen Soil Strength Criteria

This paper presents a design approach to analyze the effects of lateral loads on piles embedded in a layered frozen soil profile. This design approach makes use of a commercially available computer program that uses p-y curves to model lateral pile loading and soil interaction. Shear strength and strain criteria for both fine-grained and coarse-grained frozen soil are presented for use in constructing p-y curves. These strength criteria are parameterized based on frozen soil temperature and load duration. Inuvik lateral pile load test measurements and deflections calculated using the strength criteria are compared. This comparison indicates that reducing shear strengths by a safety factor of 1.22 will ameliorate most unaccounted-for variations in soil profile. Deflections and moments are also calculated using the strength criteria for two Prudhoe Bay, Alaska, lateral pile load cases.

Load Path Effects in Circular Steel Columns under Bidirectional Lateral Cyclic Loading

AbstractRigorous numerical analyses are conducted to study the effects of bidirectional lateral cyclic loading on the hysteretic response of stocky circular thin-walled steel columns. Four unidirectional and eight bidirectional lateral displacement controlled load paths are considered; different performance indices obtained from the lateral load paths under consideration are compared. The results obtained from these comprehensive numerical analyses indicate that bidirectional lateral cyclic loading has a very limited effect on the ultimate strength of stocky circular thin-walled steel columns, but significantly decreases the ductility when compared with unidirectional lateral loading.

Numerical Analysis of Pile–Soil Interaction under Axial and Lateral Loads

In this paper, the analysis of a numerical study of pile–soil interaction subjected to axial and lateral loads is presented. An analysis of the composite pile–soil system was performed using the finite difference (FD) software LPILE. Two three dimensional, finite element (FE) models of pile–soil interaction have been developed using Abaqus/Cae and SAP2000 to study the effect of lateral loading on pile embedded in clay. A lateral displacement of 2 cm was applied to the top of the pile, which is embedded into the concrete pile cap, while maintaining a zero slope in a guided fixation. A comparison between the bending moments and lateral displacements along the depth of the pile obtained from the FD solutions and FE was performed. A parametric study was conducted to study the effect of crucial design parameters such as the soil’s modulus of elasticity, radius of the soil surrounding the pile in Abaqus/Cae, and the number of springs in SAP2000. A close correlation is found between the results obtained by the FE models and the FD solution. The results indicated that increasing the amount of clay surrounding the piles reduces the induced bending moments and lateral displacements in the piles and hence increases its capacity to resist lateral loading.

Design of RC frames for pre-selected collapse mechanism and target displacement using energy–balance

In earthquake-prone countries, structures may be exposed to several seismic loads in any stage of building’s life. It is expected that the structures designed by engineers will show ductile behaviour under the effect of vertical and lateral loads and remain stable without making a sudden collapse. In consequence of nonlinear behaviour, plastic hinges are expected to form in structural members which are under the effect of external loads. Earthquake input energy is dissipated in plastic hinges, so, structures behave ductile. In this study, total energy of RC frames is calculated and the energy-based base shear force is determined by equating the total internal energy to the work done by external lateral design forces for pre-selected target displacement and collapse mechanism. Sections of RC frames are controlled if they can resist the calculated design lateral loads or not. If the capacity of the sections cannot withstand the external design loads, the design is rearranged and new sections are chosen. Beam and column sections that can resist the design loads securely are accepted as final sections of the energy-based design methodology. Pre-selected target displacement for desired performance level is checked using the results of nonlinear analyses. The results of the presented design methodology in this study are compatible with the results of nonlinear analyses.

Effect of lateral static load on immediately restored implants: histologic and radiographic evaluation in dogs

The aim of this study was to evaluate the effect of lateral static load in immediately restored implants in the canine mandible. In 7 mongrel dogs, all premolars and the first molars were extracted bilaterally in the mandible. Two months after the extractions, 6 implants with sandblasted acid-etched surfaces were placed in each animal, 3 on each side. Randomly, two implants per side were immediately restored with an orthodontic expansion device that promoted lateral excessive static load (test group) or load (control) while the third implant of each side, remained submerged (unloaded group). These loaded devices were cleaned daily with chlorhexidine 0.12%, during the 4 months of study, when the animals were sacrificed and biopsies removed for histometric study. Intra-oral periapicals were made using positioners at the beginning and at the end of the study. Five implants from test group were lost in 3 dogs. Radiographically, there was a marginal bone loss of 3.68 ± 0.74 mm for the test group, 1.63 ± 0.2 mm for the control group and 0.45 ± 0.5 mm for the unloaded group. Histometrically, the percentage of bone-to-implant contact (BIC%) was 35.52 ± 7.32%, for the test group, 63.16 ± 5.16% for the control group and 42.33 ± 2.14% for the unloaded group. In conclusion, the excessive lateral static load negatively affected the behavior of peri-implant bone around immediate restored implants.

Control of Building Sway and Force Flows Using Ultralightweight Slabs

AbstractDesign analyses are presented to demonstrate the technical advantages of substituting ultralightweight slab materials like cross-laminated-timber (CLT) for reinforced concrete (RC) floors and roofs of low-rise and high-rise hybrid building superstructures. Such substitution reduces the gravitational masses of slab by at least two-thirds without reducing functionality as bending or diaphragm slabs. Specific illustrations of design impacts of using CLT are given for hybrid building superstructures where steel or RC frameworks are the primary means of resisting effects of gravity forces associated with occupied built spaces. Results shown apply to two-story buildings in which effects of lateral forces associated with wind or seismic loads are resisted entirely by a steel moment framework, and six- and twenty four–story buildings in which RC shear walls within building cores primarily resist effects of such lateral loads. Consideration is also given to how fire engineering design decisions can impact ...