RC Walls Research Articles

Experimental Evaluation of PC Non-Bearing Wall System for the Damage Control of RC Wall Type Apartments

Experimental Evaluation of PC Non-Bearing Wall System for the Damage Control of RC Wall Type Apartments

A proposal of Visual Rating method to set the priority of detailed evaluation for masonry infilled RC building

In developing countries, an enormous stock of vulnerable buildings is to be considered for seismic evaluation, which requires a rigorous analysis with much expertise, cost, and time. Identification of most vulnerable buildings beforehand would be helpful in prioritizing the detailed seismic evaluation. This study aims to develop a quick seismic evaluation method, designated as Visual Rating method, in order to set the priority of vulnerable building to be gone through detailed evaluation. The proposed method approximately estimates the seismic capacity of a building, in terms of Visual Rating Index, considering cross-sectional areas and shear strength of RC columns and walls. This is followed by a modification of seismic capacity to reflect the effect of different building attributes such as structural configuration, buildings deterioration, and year of construction etc. Applicability of the proposed Visual Rating method has been investigated using post-earthquake damage database of the 2016 Taiwan earthquake. The obtained results show that the lower Visual Rating Index corresponds to severely damaged buildings in the 2016 Taiwan earthquake and the proposed method could be applied for identifying the most vulnerable buildings.

Equivalent analytical modeling of adequate reinforcement noncontact lap splices under monotonic loads

AbstractLap splices constructional details are widely used for connecting prefabricated parts. They are usually located in regions where larger inelastic deformation capacity can be expected, such as the base of RC walls and beam‐column joints. An equivalent analytical model of adequate reinforcement noncontact lap splices is first proposed in this study. The noncontact lap spliced reinforcement is simplified as continuous reinforcement with variable diameter combined with the equivalent stress–strain law. The method allows for monotonic yield and degradation of tension and compression noncontact lap splices. Parametric analysis is further performed to investigate the influence of lap splices details on the bearing capacity and deformation capacity. Finally, five shear wall finite element models are established to verify the equivalent modeling method. The proposed method can more accurately reflect the deformation capacity and bearing capacity of the noncontact lap splices region.

Characterization and optimization of a steel beam to RC wall connection for use in innovative hybrid coupled wall systems

Steel-concrete hybrid solutions with replaceable fuses as coupling elements and appropriately detailed composite connections have shown their efficiency to design safe and easily repairable earthquake-resisting structures. In this general framework, the behavior of a possible steel to concrete composite connection to be used in a recently suggested Hybrid Coupled Wall (HCW) system, consisting of a reinforced concrete shear wall coupled with steel side columns via dissipative steel shear links, is studied in this paper. The steel shear links are bolted to a steel profile either partly embedded or passing through the RC wall. The connection zone is designed in such a way that the damage always occurs in the steel shear links (fuses) prior to any damage in the RC wall in general and in the connection zone in particular. The emphasis lies therefore on the characterization of a suitable “steel link + embedded composite connection within the RC wall” configuration and on the evaluation of an appropriate embedment length allowing the concentration of seismic damage to the replaceable steel links. To this purpose, two joint configurations are designed based on a capacity-based approach, namely “partly embedded” and “completely passing through” steel beam, and are examined through detailed FE analyses. A parametric study is carried out to provide sufficient insight into the system in terms of strength, stiffness and local bearing strength, in view of validating the proposed design procedure.

DEVELOPMENT OF INTERNAL THERMAL SYSTEM FOR RC WALL USING VACUUM INSULATION PANEL AND ITS EVALUATION OF THERMAL INSULATION PERFORMANCE

In order to upgrade internal thermal system for RC wall with less spatial loss, a new site-fabricable thermal system using quite thin vacuum insulation panel(VIP:5 mm and 8 mm) is developed here and compared with traditional XPS thermal system(45 mm) by Calibrated Hot box Method. In this new system, small pieces of plastic blocks in place of furring strips are arranged on lattice points of a square lattice on RC wall with VIPs in between them and with VIP joints covered by site spray foam. VIP system shown close score to Japanese Flat35 standards whereas XPS shown adequate score to it. For further upgrading of new system, improvement of joint heat bridge will be necessary.

Seismic performance analysis of multi-story RC frames strengthened with RC infill wall

Seismic performance of RC frame structures was investigated by creating 3-D models of the frame with additional solid RC infill wall along the height of Honolulu Building prescribed in FEMA design examples. Layered-shell element (LSE) was used to model the infill wall and gap element was introduced at the interface between the wall and the bounding frames. The modelling technique was validated against test results reported in the literature prior to its application on the 12 story building. The push over curves of all models were compared to obtain the most efficient model that conform to the strength and stiffness requirement of the seismic codes of Indonesia. The results showed that the non-linear behaviour of RC frame with RC infill wall can be modelled accurately using LSE and gap element. The RC wall addition improved the strength, stiffness and performance of the frame significantly. The most efficient model was that with infill wall up to the first 4 story levels in which, the performance of the structure improved from collapse prevention to immediate occupancy.

Cyclic behaviour of expanded polystyrene (Eps) sandwich concrete walls

Precast concrete walls become increasingly utilized due the rapid needs of inexpensive fabricated house especially as traditional construction cost continue to climb. Moreover, particularly at damaged area due to natural disaster when the requirement of a lot of fast-constructed and cost-efficient houses are paramount. However, the performance of precast walls under lateral load such as earthquake or strong wind is still not comprehensively understood due to various type of reinforcements and connections. Additionally, the massive and solid wall elements also increase the total weight of building and hence increase the earthquake base shear force significantly. Therefore, the precast polystyrene reinforced concrete walls which offers light weight and easy instalment became the focus of this investigation. The experimental test on two RC wall specimens using EPS (Expanded Polystyrene) panel and wire mesh reinforcement have been conducted. Quasi-static load in the form of displacement controlled cyclic tests were undertaken until reaching failure. At each discrete loading step, lateral load-deflection behavior, crack propagation and collapse mechanism were measured which then were compared with theoretical analysis. The findings showed that precast polystyrene reinforced concrete walls gave sufficient seismic performance reaching up to 1% drift at failure point against lateral.

Experimental investigation on the deformation capacity of lap splices under cyclic loading

Correct detailing and positioning of lap splices is essential in order to prevent premature failure of reinforced concrete structural members. Especially before the introduction of capacity design guidelines, lap splices were often placed in member regions that undergo inelastic deformations under earthquake loading. When assessing the seismic performance of such members, not only the lap splice strength, which was assessed in previous studies, but also information on the deformation capacity of lap splices is required. This paper analyses the results of a recently concluded experimental programme on spliced RC wall boundary elements tested under uniaxial tension–compression cyclic loading. The study aimed at investigating the influence of lap splice length, confining reinforcement and loading history on the deformation capacity of lap splices. The latter is defined as the average strain, at the onset of splice failure, ascribed to deformations originating from the lap splice zone. Analysis of the test results showed that the deformation capacity of lap splices: (1) increases with lap splice length; (2) increases with confining reinforcement but the effectiveness of the confining reinforcement is dependent on the lap splice length; (3) decreases with larger imposed compression levels; (4) is larger for bottom-casted with respect to top-casted lap splices. Finally, an empirical model is proposed to estimate the strain capacity of lap splices, which provides a good fit with the experimental results.

Assessment of a force–displacement based multiple-vertical-line element to simulate the non-linear axial–shear–flexure interaction behaviour of reinforced concrete walls

A comprehensive assessment of a new version of the macroscopic force–displacement based multiple-vertical-line element (SFI-MVLEM-FD), which can be used to simulate non-linear axial–shear–flexure interaction in RC walls, is presented. The element models the shear response taking into account all the basic physical mechanisms that transfer shear forces over cracks: (a) the dowel effect of vertical bars, (b) the axial resistance of horizontal/shear bars, and (c) the interlocking of aggregate particles in cracks. In order to provide a wide range of its use, and to enable the analysis of various types of buildings, the SFI-MVLEM-FD element was included in the local version of the OpenSees program system. The element was assessed with respect to already performed quasi-static cyclic experiments of various RC shear walls. In this paper, the results of numerical analyses of two representative rectangular walls, where the influence of shear on the overall response was of particularly significance, are presented and compared with those obtained in the experiments. In order to estimate the efficiency of the new element in more general cases, it was also assessed by means of a large-scale shake-table test of a typical non-planar lightly reinforced RC coupled wall. The test examples showed that the SFI-MVLEM-FD model can capture all the important mechanisms of the response, as well as being able to efficiently describe the axial–shear–flexure interaction in various types of RC walls: (a) rectangular and non-planar, (b) cantilever and coupled, and (c) subjected to different types of excitation, uni-axial or bi-axial. It was found that the model is capable of clearly identifying the three fundamental mechanisms, which contribute to shear resistance. This is one of the few models, which are able to describe the significant deterioration of the (shear) strength of RC walls that are near to collapse for different reasons: e.g. the buckling of their longitudinal bars, rupture of the horizontal reinforcement, and other significant degradation of different types of shear mechanism. This makes it suitable for the analysis of different types of RC walls, which are subjected to different levels of seismic excitations. It is even able to simulate the near collapse response influenced by very different collapse mechanisms.

A contribution to the seismic performance and loss assessment of old RC wall-frame buildings

This paper deals with the seismic performance and loss assessment of old RC wall-frame buildings in Lisbon, Portugal. These structures are characterised by non-ductile columns and RC walls made with smooth rebars and light transversal reinforcement. They were erected before the introduction of modern seismic codes in the 1980s and represent an important proportion of the city’s building stock. The research reported in this paper focuses on the seismic vulnerability assessment of this building typology. An analytical procedure is proposed to estimate the fragility functions of non-ductile reinforced concrete walls with smooth reinforcing bars and light transversal reinforcement, taking into account strength penetration effects. To illustrate the procedure, a case study building is considered. The approach used for the seismic performance assessment adopts component-based fragility and loss functions for the damage assessment of the structural and non-structural drift-sensitive elements, adapted to the Portuguese reality, and a storey-based approach for acceleration-sensitive non-structural elements. The results provide the economic loss of the building as a function of the ground motion intensity level. Finally, results are compared in terms of expected annual losses with other non-ductile RC building typologies.

Nonlinear cyclic Truss Model for analysis of reinforced concrete coupled structural walls

This paper discusses the Truss Model proposed by Panagiotou et al. (ACI Struct J 109(2):205–214, 2012) for modeling reinforced concrete coupled structural walls. The model is validated with the landmark seismic testing of two 1:4 scale seven-story test specimens reported in Santhakumar (The ductility of coupled shear walls. Dissertation, University of Canterbury 1974) and in Paulay and Santhakumar (J Struct Div 102(1):93–108, 1976). The first specimen, Wall A, incorporated conventionally reinforced coupling beams whereas the second specimen, Wall B, incorporated diagonally reinforced coupling beams. These two specimens attained roof drift ratios of at least 1.7% before initiation of lateral strength degradation. Coupling beams in specimen Wall A exhibited significant strength degradation due to sliding shear, whereas coupling beams in specimen Wall B maintained the capacity throughout. We compare key overall and local responses reported for the two specimens with those computed with the Truss Models, as well as responses that could be only computed. In the latter, we show that when the beams effectively coupled the walls, the shear force at the wall base was mainly resisted by the wall being compressed. Moreover, the analysis shows that the first level coupling beams develop greater shear forces than the other beams despite all beams were identically reinforced. This is caused by the restraint provided by the fixed-base walls and by the kinematics of the strongly coupled walls. The Truss Model captures these responses because it explicitly considers the axial-flexure-shear interaction of RC walls and beams.

Analytical Comparison of Structure with Reinforced Concrete Wall Against Lateral Load

Buildings are generally designed to withstand against gravity load for expected life and resist extent of lateral loads by satisfying the codal provision. Main objective of structural elements is to transfer the load safely to the ground, which depends on structural system adopted. Generally, structural system can be adopted depending on the demand of client/building needs/use of structure, environmental condition, performance optimization, economic condition etc. For high rise building moment resisting frame system, structural wall systems, dual system, flat slab-structural wall systems can be employed. A residential ground with ten upper floors high rise building situated in zone-III has been taken under reference, where MRF with RC structural wall system is used. Structural parameters are compared in the study for various location and orientation of RC wall. Linear static and dynamic analysis is performed on the structure based on the IS 1893 Part-I on ETABS software.

Response of RC Walls Subjected to Tsunami Debris Collision by Nonlinear Finite Element Analysis

Response of RC Walls Subjected to Tsunami Debris Collision by Nonlinear Finite Element Analysis

A parametric investigation on applicability of the curved shell finite element model to nonlinear response prediction of planar RC walls

This study investigates the ability of a finite element model based on curved shell element formulation in predicting nonlinear behavior of planar RC structural walls, identifying the strengths and limitations of this modeling approach. For this purpose, a parametric validation is conducted in addition to verification of the model simulation against experimental results of several wall specimens tested in literature. The effects of variations in total length, thickness, shear-span ratio, axial load ratio, confinement, as well as the horizontal and vertical reinforcement ratios are investigated at both global and local levels. For scrutinizing the global response, lateral load versus total, flexural and shear deformation predictions are used. For local response, sensitivity of the stress and strain distributions throughout the length and height of the wall models to the parameters noted above is evaluated. The capabilities and deficiencies of the modelling approach are discussed in detail in light of the numerical versus experimental as well as parametric verifications. The model is found to be able to predict most of the experimentally observed failure mechanisms of rectangular walls including global out-of-plane instability under in-plane loading, concrete crushing at the base, diagonal tension and diagonal compression as well as sliding shear. The model is not able to represent bar buckling, bar fracture and the potential subsequent secondary failure modes such as instability of the compression boundary zone due to progressive asymmetric concrete crushing at the base. The parametric study indicated sensitivity of the model response to the variation of the parameters known to be influential on the nonlinear response of planar RC walls.

Understanding the cyclic response of RC walls with setback discontinuities through a finite element model and a strut-and-tie model

Slender RC walls are often used in Chile and commonly, due to architectural constraint, the length of walls increases (setback) between floors designated for parking space and upper floors. These types of elements are commonly called flag walls. In this research, the behavior of slender reinforced concrete walls with a constant axial load and a cyclic lateral displacement is numerically studied, in order to compare the results obtained with previous tests. Two different model alternatives are considered: a finite element model and a strut-and-tie model. The selected models allow understanding local response, as well as, distribution of internal forces, which is also relevant information for wall design and detailing. The studied finite element model, based on quadrilateral elements with 3 degrees of freedom per node (2 translational and 1 rotation) and a model of smeared reinforced concrete material based on a rotating angle approach, is able to correctly capture the global response, showing the capacity, degradation and failure mode obtained in the tests. On the other hand, a parametric analysis is performed for models of walls with higher aspect ratio (tall buildings) with small discontinuities, showing a larger impact in deformation capacity due to the high concentration of damage at the discontinuity. These results indicate that in 25-floor high walls (or taller) a reduction of displacement capacity of 40% for discontinuities located at the first floor could be observed. In addition, by incorporating the effect of the slabs into the model, the results indicate that a pure flexure model is an adequate and sufficient tool for analysis. Finally, a strut-and-tie model is also proposed for each direction of the lateral load, whose results are compared with the estimated load calculated with the strains measured by photogrammetry. The considered strut-and-tie model for the case of lateral load with tension in the continuous wall boundary is similar to the wall without discontinuity, which is consistent with the measured strains. For both lateral loading directions, the estimated forces of the horizontally distributed bars and boundary reinforcements are consistent with photogrammetry in the lower zone of the wall, where cracking is relevant. The strut-and-tie model also adequately interprets the effect of the discontinuous bar on the discontinuous boundary of the wall. All these results can help designing and detailing flag walls.

Experimental Study on RC Walls with Opening Strengthened by Externally Bonded CFRP

AbstractRC walls with an opening under eccentric axial loads exhibit cracks around the opening leading to a reduction in the ultimate strength of the wall. These cracks are mainly due to changes in...

Blast Load Assessment: RC Wall Subjected to Blast Load

The evaluation of the pressure produced by blast load on the structure surface and selected location around with the aid of hydrocodes is studied in this paper. The existing knowledge of predicted blast pressure has been embraced in this paper for initial design in engineering application. The acquired blast parameters from numerical results are compared with blast test data and empirical methods. Besides the comparison, the effects of mesh distribution and air volume size on pressure are also studied. The numerical simulation initially conducted in 3D free air explosion and followed by the consideration of an obstruction structure on the blastwave propagation. The numerical peak incident overpressure indicated, the pressure of 0.51 MPa at 4.62 msec is approximates the overpressure recorded in the explosive test carried out at Fort Leonard Wood Army Base. It is revealed numerically, the overpressure at the bottom part on the wall surface experienced the higher overpressure.

Seismic response of dual structures comprised by Buckling-Restrained Braces (BRB) and RC walls

In order to reduce the residual drift of a structure in structural engineering field, a combined structural system (dual) consisting of steel buckling-restrained braced frame (BRBF) along with shear wall is proposed. In this paper, BRBFs are used with special reinforced concrete shear walls as combined systems. Some prototype models of the proposed combined systems as well as steel BRBF-only systems (without walls) are designed according to the code recommendations. Then, the nonlinear model of the systems is prepared using fiber elements for the reinforced concrete wall and appropriate elements for the BRBs. Seismic responses of the combined systems subjected to ground motions at maximum considered earthquake level are investigated and compared to those obtained from BRBFs. Results showed that the maximum residual inter-story drift from the combined systems is, on average, less than half of the corresponding value of the BRBFs. In this research, mean of absolute values of the maximum inter-story drift ratio demand obtained from combined systems is less than the 3% limitation, while this criterion has not been fulfilled by BRBF systems.

Evolution of Crack Control Method for RC Walls Based on Shrinkage Mechanism of Concrete

Evolution of Crack Control Method for RC Walls Based on Shrinkage Mechanism of Concrete

The length of plastic hinge area in the flanged reinforced concrete shear walls subjected to earthquake ground motions

Past earthquakes have shown that appropriately designed and detailed buildings with shear walls have great performance such a way that a considerable portion of inelastic energy dissipation occurs in these structural elements. A plastic hinge is fundamentally an energy diminishing means which decrease seismic input energy through the inelastic deformation. Plastic hinge development in a RC shear wall in the areas which have plastic behavior depends on the ground motions characteristics as well as shear wall details. One of the most generally used forms of structural walls is flanged RC wall. Because of the flanges, these types of shear walls have large in-plane and out-of-plane stiffness and develop high shear stresses. Hence, the purpose of this paper is to evaluate the main characteristics of these structural components and provide a more comprehensive expression of plastic hinge length in the application of performance-based seismic design method and promote the development of seismic design codes for shear walls. In this regard, the effects of axial load level, wall height, wall web and flange length, as well as various features of earthquakes, are examined numerically by finite element methods and the outcomes are compared with consistent experimental data. Based on the results, a new expression is developed which can be utilized to determine the length of plastic hinge area in the flanged RC shear walls.