Article

Analytical and experimental studies on infilled RC frames

Department of Civil Engineering, Kirikkale University, 71450, Yahsihan, Kirikkale, Turkey
International Journal of the Physical Sciences 11/2010; 5:1981-1998.

ABSTRACT Although hollow brick infills, widely used as partition walls, are considered as non-structural members, experimental studies revealed that hollow brick infills have favourable effects on strength and stiffness of structures. In this work, analytical studies were conducted to investigate the hollow brick infill behaviour, in which infills were modeled by diagonal compression struts. Results were compared with experimental ones obtained from tests of one-bay, one or two story reinforced concrete (RC) frames, tested under both vertical and reversed-cyclic lateral loads simulating earthquake. Test frames have intentionally been constructed poorly to reflect the most common deficiencies encountered in Turkey such as strong beam-weak column connections, insufficient confinement, low-grade concrete, poor workmanship and insufficient lap-splice length. Experimental studies shows that hollow brick infills increased both strength and stiffness of RC frames. Analytical studies conducted, shows that hollow brick infills could adequately be modeled by diagonal compression struts.

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    • "Since the focus of this paper is on modelling, only a few, major tests on one-bay one storey and multi-bay multi-storey structures are reviewed. Three main test types are listed as: quasi-static (Mosalam et al. 1997, Amato et al. 2008, Kakaletsis and Karayannis 2008, Personeni et al. 2008, Baran and Sevil 2010), pseudo-dynamic (Negro and Verzelletti 1996, Mosalam et al. 1998, Dolsek and Fajfar 2002) and full dynamic testing (Fardis et al. 1999, Albanesi et al. 2008, Liu et al. 2011). For monotonic tests on a one-bay single-storey masonry infilled RC frame designed to have infill rather frame failure, it is experimentally observed that as the lateral load increases and the deformation demand becomes large, diffuse cracking evolves starting from the middle of the panel and progresses along the tensile stress principal directions. "
    Earthquakes and Structures 03/2015; 8(3):733-759. DOI:10.12989/eas.2015.8.3.733 · 1.14 Impact Factor
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    • "Those studies have, in turn, led to the development of rational design models based on the strut and tie approach for the design of membrane elements (Rogowsky and Macgregor, 1986; Rogowsky, 1997; Zhang and Tan, 2007; Bakir and Boduroglu, 2005). The strut and tie model has been used in analysis and design of disturbed regions, beam strengthened with FRP and infill frames and walls in masonry and reinforced concrete structures (Kuo et al., 2010; He and Liu, 2010; Shah et al., 2011; Colotti and Swamy, 2011; Seim and Pfeiffer, 2011; Baran and Sevil, 2010; Güney and Kurusçu, 2011). Despite of the large amount of research carried out on reinforced concrete membrane structures, there is no agreed rational procedure to predict the strength of these structures. "
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    ABSTRACT: In this study, a nonlinear finite element (FE) model is proposed to investigate the behaviour and failure mechanism of reinforced concrete membrane structures. Proven accurate stress-strain relation is incorporated in the model to describe the stress-strain behaviour of the concrete under compression for uniaxial and biaxial stress system. The nonlinearity behaviour of the materials in the compressive stress field is considered for the concrete in the orthogonal directions. The effect of micro cracking confinement and softening on the stress-strain relationship under biaxial stresses are included by employing the equivalent uniaxial strain concept. Tension stiffening effect by concrete in tension is modelled in the ascending and descending parts. The model allows for the progressive local failure of the reinforced concrete materials. The applicability of the proposed FE model is investigated by demonstrating the nonlinear structural response and failure mechanism of a simple deep beam and validated with published experimental work. Good agreement is achieved between the developed FE model and the experimental test results which gives confidence that the approach is fundamentally correct.
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    ABSTRACT: The influence of masonry infills on the in-plane behaviour of RC framed structures is a central topic in the seismic evaluation and retrofitting of existing buildings. Many models in the literature use an equivalent strut member in order to represent the infill but, among the parameters influencing the equivalent strut behaviour, the effect of vertical loads acting on the frames is recognized but not quantified. Nevertheless a vertical load causes a non-negligible variation in the in-plane behaviour of infilled frames by influencing the effective volume of the infill. This results in a change in the stiffness and strength of the system. This paper presents an equivalent diagonal pin-jointed strut model taking into account the stiffening effect of vertical loads on the infill in the initial state. The in-plane stiffness of a range of infilled frames was evaluated using a finite element model of the frame-infill system and the cross-section of the strut equivalent to the infill was obtained for different levels of vertical loading by imposing the equivalence between the frame containing the infill and the frame containing the diagonal strut. In this way a law for identifying the equivalent strut width depending on the geometrical and mechanical characteristics of the infilled frame was generalized to consider the influence of vertical loads for use in the practical applications. The strategy presented, limited to the initial stiffness of infilled frames, is preparatory to the definition of complete non-linear cyclic laws for the equivalent strut.
    Bulletin of Earthquake Engineering 12/2014; 13(8). DOI:10.1007/s10518-014-9714-x · 1.37 Impact Factor
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