Infilled Frame Buildings Research Articles

Effect of prevalent irregular configuration of infills on the seismic collapse of Indian RC buildings

Rapid urbanization and land scarcity obligated the urban population for multi-use of Reinforced Concrete (RC) buildings to meet both residential and commercial purposes together. Un-Reinforced Masonry (URM) infills are often placed irregularly in plan and or elevation of the buildings in some floor(s), particularly in the ground floor to suit the need of occupational requirements accompanied by the inherent irregularities due to openings for doors and windows to meet functional requirements for residence. Seismic performance of infilled frame highly depends upon degree of infill-frame interaction, and it is of utmost importance to classify infilled frame buildings in various Model Building Types (MBTs) based on the type of irregular placement of infills in addition to the parameters affecting seismic performance. Based on field pilot surveys carried out in Indian cities, URM infilled buildings have been classified into 14 different MBTs. Seismic performance of the prevalent categories of MBTs have been evaluated through Incremental Dynamic Analysis (IDA). It has been observed that irregular placement of infills increases the seismic collapse risk significantly, and reduces collapse capacity to approximately 50% as compared to ideal uniformly infilled building. Global collapse occurred due to failure of structural members in the vicinity of irregularity created due to infills.

Seismic Reliability Maps of Code-Compliant Italian Reinforced-Concrete Bare and Infilled Frame Buildings

The present study illustrates the main results of an extensive campaign of numerical simulations aimed at quantifying the seismic reliability of reinforced concrete (RC) bare and masonry-infilled frames compliant with the current Italian Building Code. For this purpose, a set of different residential-use archetype structures are considered, and a prototype seismic design-assessment tool is created to quantify their performance with respect to the relevant limit states, deriving fragility curves via the execution of several non-linear time-history analyses (NLTHAs). The fragilities are subsequently combined with the hazard curves derived for each of the over 8000 Italian municipalities based on the national seismic hazard model currently in force to obtain the respective seismic mean failure rates across Italy. The seismic reliability maps obtained for the investigated code-compliant designs highlight how the current Italian Building Code fails to provide uniform seismic safety across Italy, showing—on the contrary—a strong hazard-dependency. The results are finally used to calibrate regression laws able to correlate the seismic mean failure rates with an intensity measure representative of the seismic hazard.

Behaviour of Masonry-Infilled RC Frames Strengthened Using Textile Reinforced Mortar: An Experimental and Numerical Studies Overview

ABSTRACT A large part of the existing building stock was not designed according to the current codes in seismic prone regions. The poor performance of some reinforced concrete structures was related to the presence of the masonry infill walls. Although the infill walls can increase the lateral resistance of frames in many cases, it is widely recognized that there is a high vulnerability of the masonry infill walls subjected to loadings along and perpendicular to their plane. Several collapses were observed after past earthquakes in infilled frame buildings. For this reason, different retrofitting design approaches have been proposed and used during the last years; however, many of them do not fit with the building’s owners’ economic demands or technical knowledge of the workmanship. Over the years, significant research has been conducted for masonry wall elements retrofitted with textile-reinforced mortar (TRM). However, much less has been carried for masonry-infilled frame RC frames. Thus, this manuscript aims to provide a literature review about research on assessing the effectiveness of using TRM technique to reduce masonry-infilled RC frames’ seismic vulnerability. Experimental findings will be deeply analysed to provide full insight concerning the TRM’s efficiency under in-plane and/or out-of-plane demands of infilled frames and some variables such as anchorage of the TRM to the structure. Numerical modelling approaches to simulate the complex behaviour of infilled frames with TRM are also presented to stress their benefits or limits. Covering completely all aspects of this manuscript is essential to briefly describe the studies conducted so far to examine either numerically or experimentally the effectiveness of using TRM for retrofitting masonry wall elements.

Studi Penggunaan Balok Lintel Pada Bangunan Gedung Infilled Frame 2 Lantai Menggunakan SAP2000

The two stories building construction or which is commonly called the two stories building these days is very popular in Indonesia. The type of multistories building technology that develop in the world of construction is very diverse, this development is can not be separated from the anticipation of the various of loading conditions.
 Based on that facts, the research of the use of lintel beams in 2 stories infilled frame buildings is conducted. The analysis can be done by using SAP2000 software. The structure model analyzed by comparing the structure responses between the building that use the lintel beams system and the other one is the building that don’t use that system, where as the idealized loading is same.
 The result of the analysis obtained by using the lintel beams system the value of maximum x and y axis base shear respectively are 344,088 KN and 363,001 KN, the maximum column moment is occurred in column 84 with the value is 99,58 kNm, and the maximum x axis lateral drift is occurred in joint 128 with the value is 0.000401 m, while the y axis is occurred in joint 105, 128 with the value is 0,000533 m. The analysis result that obtained for the building that don’t use the lintel beam system, the x and y axis maximum base shear value respectively is 336,425 KN and 354,539 KN, the maximum column moment occurs in column 84 is 98,98 kNm, and the x axis maximum drift lateral occurs in joint 128 with value is 0,000406, while the y axis maximum lateral drift occurs in joint 105, 128 with value is 0,000532. So we obtained the percentage comparison on base shear value between 2 stories infilled frame building that use lintel beams system and the building that doesn’t use the lintel beams system for x axis is 1,45% and y axis is 1,13% , and for the percentage comparison on maximum column moment value is 0,30% , while the percentage comparison on drift lateral value for x axis is 0,62% and y axis is 0,09%

Towards the vulnerability assessment of low-code RC frame buildings at precarious slopes subjected to rainfall induced landslide hazard

The presence of capillary pressure in unsaturated soils may, under certain circumstances, significantly affect the stability of a slope and the safety of a structure standing in the vicinity of its crest. More specifically, the change in saturation induced by a rainfall event may directly influence the value of apparent soil cohesion potentially resulting in excessive permanent slope displacements and subsequent structural damages for the structure standing on it. Under these considerations, this study aims at the vulnerability assessment of typical reinforced concrete (RC) buildings on precarious slopes subjected to rainfall induced landslide hazard. The proposed methodology is based on a two-step numerical analysis procedure. First, the permanent absolute and differential ground displacement time histories at the assumed building location within the landslide zone are evaluated performing coupled mechanical-flow analysis of a generic initially unsaturated natural slope configuration considering the employment of different rainfall events of increased intensity at the surface of the slope model. Different soil properties of the surface layer are considered to represent silty and soft clayey soil material. Appropriate analytical relationships between the rainfall intensity and its duration and the computed permanent displacements are extracted. Then, a series of nonlinear static time history analyses are performed for reference low and mid-rise, low-code RC bare and infilled frame buildings located next to the slope's crest to assess their fragility. The buildings’ response assessed using appropriate engineering demand parameters (EDPs) to account for both the global flexural and local shear demand are statistically correlated with predefined damage limit states to construct the fragility functions. To facilitate the applicability of the proposed methodology within a quantitative landslide risk assessment framework, vulnerability curves are finally developed to quantify the expected direct losses in normalised cost terms.

Characterization of local and global capacity criteria for collapse assessment of code-conforming RC buildings

The paper investigates both local and global capacity criteria for collapse assessment of RC frame buildings. Both literature and regulations criteria are considered, also including the formulation recommended in the draft of the new Eurocode 8 (part 3) and other collapse criteria never investigated. The case studies consist of low-rise bare and infilled frame buildings, which are designed according to the Italian code provisions considering low-to-high seismicity sites in Italy. The seismic demand is estimated by performing multiple-stripe analysis based on inelastic modeling, also including the presence of the infills. The capacity assessment and the performance evaluation associated with the (building) collapse are carried out according to the latest approaches and methodologies of performance-based earthquake engineering. The investigated capacity criteria are characterized as a result of the collapse assessment in terms of (a) collapse demand to capacity ratios, (b) collapse fragility curves, (c) collapse margin ratios and probabilities, and (d) inter-capacity margin ratios. The findings provide novel information and technical insights into the influence of the collapse capacity criteria selection on the collapse features of the investigated buildings. In particular, the capacity criteria are quantitatively correlated to the building collapse performance, also outlining safety and economic considerations.

A probabilistic simplified Seismic Model from Ambient Vibrations (SMAV) of existing reinforced concrete buildings

SMAV (Seismic Model from Ambient Vibrations) is a mathematical model for predicting the seismic response of an existing building subjected to earthquake that produces no severe damage. The model is based on the identification of the building experimental modal parameters from ambient vibration together with few information about its geometry and constructive typology. The dynamic response of the structure is obtained by a modal superposition where all the inertial properties are concentrated in the center of gravity of the floors or floor sections. The non-linear behavior, which typically occurs during even nondestructive earthquakes, is considered by assigning appropriate laws of variation to the natural frequencies as the deformation increases.This paper presents the development of SMAV to reinforced concrete frame buildings with infill walls and the application to real cases. Specific Frequency Shift Curves (FSCs), that relates the vibration amplitude to the variations of the natural frequencies, have been developed. Such FSCs are a fundamental feature of SMAV, because they allow the seismic nonlinear behavior to be simulated through an equivalent iterative linear analysis. Therefore, in order to comply with the declared aim, in this work the attention is focused on the definition of a suitable simplified model for the generation of FSCs, valid for reinforced concrete frame buildings with infill walls. In the adopted model the global behavior of the infilled frame is simulated by considering the two components of the system, i.e the bare frame and the infill masonry panel, as working in parallel. The mutual interaction between them is modeled by suitably modifying the collapsing mechanism of the masonry panel. The stochastic approach for modeling the seismic response of infilled RC buildings, considering different kinds of infills and taking account of the nonlinearity which arises during a seismic event, is illustrated in detail. The validation of the FSCs has been performed by using the experimental seismic response of buildings as recorded by permanent accelerometric monitoring systems. Finally, two case studies related to the seismic response recorded on a regular and an irregular building, respectively, are presented by comparing the computed end experimental seismic dynamic responses, in order to prove the SMAV ability in reproducing the behavior of RC infilled frame buildings subjected to nondestructive earthquakes.

Numerička analiza armiranobetonskih okvirnih zgrada sa izolovanom zidanom ispunom

Reinforced concrete (RC) buildings with masonry infill walls are widely used in many countries all over the world. Although infills are considered as non-structural elements, they significantly change dynamic characteristics of RC frame structures during earthquake excitation. Recently, significant effort was spent on studying decoupled infills, which are isolated from the surrounding frame usually by adding a gap between frame and infill. In this case, the frame deformation does not activate infill wall, thus infills are not influencing the behaviour of the frame. This paper presents the results of the investigation of the behaviour of RC frame buildings with the INODIS system that decouples masonry infills from the surrounding frame. Effect of masonry infill decoupling was investigated first on the one-bay one-storey frame. This was used as a base for parametric study on the frames with more bays and storeys, as well as on the building level. Change of stiffness and dynamic characteristics was analysed as well as response under earthquake loading. Comparison with the bare frame and traditionally infilled frame was performed. The results show that behaviour of the decoupled infilled frames is similar to the bare frame, whereas behaviour of frames with traditional infills is significantly different and demands complex numerical models. This means that if adequate decoupling is applied, design of infilled frame buildings can be significantly simplified.

Development of Seismic Fragility Curves of RC Infilled Frame Buildings in Jordan

This article examines the seismic fragility of low- and mid-rise RC infilled frame buildings in Jordan comprising stone-concrete infill panels. Three dimensional models of 2, 4 and 6 story regular and irregular representative buildings were developed. Pushover analyses were performed to construct capacity curves of the model buildings. Four damage states were considered: slight, moderate, extensive and complete and damage state thresholds were assigned, using expert opinion, based on yield and ultimate spectral displacements of the capacity spectra. Sets of preliminary fragility curves were developed to quantify earthquake damage probabilities in terms of spectral displacements.

Energy and Seismic Upgrading of R.C. Masonry Infilled Frame Buildings: A General Perspective

Energy and Seismic Upgrading of R.C. Masonry Infilled Frame Buildings: A General Perspective

Seismic Performance of 3-D Infilled and Bare Frame RC Building Models using Average Spectral Acceleration

This study compares the performance of the bare and infilled frames of RC buildings based on incremental dynamic analysis (IDA) and fragility analysis in the Performance Based Earthquake Engineering framework. Inter story drift ratio (IDR), maximum inter-story drift ratio (MIDR) and absolute peak floor acceleration (PFA) are chosen as engineering demand parameters (EDPs). Comparing the response of such different frames is always problematic because of their very different dynamic characteristics, a feature that to ensure efficiency imposes selecting different sets of accelerograms for response assessment. To bypass this problem as common intensity measure for both types of frames we used here the spectral acceleration averaged in a period range (AvgSA) that include the first mode periods of both frames. We further derived fragility curves for six case study buildings of regular 4-, 5-, 6-, 8- and irregular 6-, and gravity designed 6-story buildings. Except for the gravity designed 6-story building, we observed that the infilled frame buildings have slightly better performance at less severe limit states. For the gravity designed building performance, however, ignoring URM infill walls resulted in un-conservative collapse capacity estimates. Finally, exploring the comparison of the PFA response of the bare and infilled frames for the 6 case study buildings confirms that significantly higher demands are to be expected for the latter, suggesting the necessity of accounting for the infills when performing detailed building-specific loss estimation analysis or designing acceleration sensitive equipment. Hence, it is recommended to account for the infill elements in both design and assessment procedure to ensure the safety of structural and nonstructural elements.

Behaviour of Reinforced Concerete Infilled Frames Under Seismic Loads

A significant portion of the buildings constructed in Algeria is structural frames with infill panels which are usually considered as non structural components and are neglected in the analysis. However, these masonry panels tend to influence the structural response. Thus, these structures can be regarded as seismic risk buildings, although in the Algerian seismic code there is little guidance on the seismic evaluation of infilled frame buildings. In this study, three RC frames with 2, 4 and 8 storey and subjected to three recorded Algerian accelerograms are studied. The diagonal strut approach is adopted for modeling the infill panels and a fiber model is used to model RC members. This paper reports on the seismic evaluation of RC frames with brick infill panels. The results obtained show that the masonry panels enhance the load lateral capacity of the buildings and the infill panel configuration influences the response of the structures.