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Performance of infill walls in reinforced concrete (RC) frames is generally questionable under the combined action of in-plane and out-of-plane seismic demands. Despite the vast number of tests investigating the behavior of brick masonry infill walls in RC frames, past research is limited for infill walls made of Autoclaved Aerated Concrete (AAC) blocks. In the first part of the study, six single-bay single-story half-scaled RC frames were tested under the action of in-plane cyclic displacement excursions and/or out-of-plane pressure. It was found that the presence of out-of-plane pressure can significantly reduce the deformation capacity of RC framed AAC infill walls. Afterwards, a new innovative system is proposed to protect the infill walls from in-plane induced forces while providing out-of-plane support. Sliding connectors placed inside the AAC blocks were used to isolate the infill wall from earthquake-induced frame deformations, while providing out-of-plane support. In order to test the beneficial effect of the proposed system, three additional tests were conducted. The proposed system managed to reach in-plane deformation demand of 2% without cracking and preserving its out-of-plane stability.

Reinforced Autoclaved Aerated Concrete (AAC) wall panels are more commonly used to construct load-bearing walls in low-rise prefabricated buildings located in seismic zones. In the scope of this study, the seismic response of buildings constructed with reinforced AAC wall panels was investigated. To this end, an in situ test was conducted on a two-story test building under reversed cyclic displacement excursions. It was determined that the test building could carry a lateral load of 60% more than its weight and has a global displacement ductility of about 3.5. The first story of the building was observed to be critical and the failure of the building was due to overturning response of the whole system. In addition, the proposed numerical models for simulating the behavior of the AAC wall panels were validated. These calibrated numerical models were utilized to conduct nonlinear static analysis of the test building and a reasonably good agreement was observed between the test results and simulations. The results of the incremental dynamic analyses demonstrated that i) the two-story test building could resist strong ground motions with PGA values up to 0.6 g without undergoing significant plastic deformations and ii) a reserve of ductility and over strength is available for the AAC panel building to survive earthquakes with PGAs reaching nearly 0.6 g. Based on these numerical results, reinforced AAC wall panel buildings appear to be good alternatives for low-rise construction in seismic regions.

Historic structures form a very important part of our cultural heritage and are supposed to be preserved properly. Therefore, full comprehension of the structural behavior of historic structures is of prior importance. In this study, a damaged single domed mosque of 16th century classical Ottoman Architecture has been investigated. Serious damage was recorded at various locations and structural elements including the dome and the structural masonry walls, as a result of which the structure was recently closed to worshippers and visitors. The mosque was constructed in the 16th century on silty–clay soil. Due to local drought conditions in the last couple of decades, the water table has changed excessively, causing soil displacements that have especially affected the masonry structure. The main objective of the present study is to explore the reasons for the structural damage and to propose a rehabilitation method suitable for the amelioration of the observed damage. The results of the structural analyses conducted have been compared with the observed damage and some rehabilitation methods have been proposed accordingly. These methods include mini-pile application proceeding as far as the firm soil (rock) in order to prevent the soil displacement. Furthermore, as the cracks on the masonry walls would be repaired using materials that would be in conformity with the structure's historical texture, it has been proposed that a steel ring be fitted suitably around the damaged dome's base in order to contain further propagation of cracks.

Summary Inspired from the simplified single degree of freedom modeling approach used in the preliminary design of concrete gravity dams, a pseudo-dynamic testing method was devised for the seismic testing of a concrete gravity dam section. The test specimen was a 1/75 scaled section of the 120-m-high monolith of the Melen Dam, one of the highest concrete gravity dams to be built in Turkey. The single degree of freedom idealization of the dam section was validated in the first stage of the study using numerical simulations including the dam–reservoir interaction. Afterwards, pseudo-dynamic testing was conducted on the specimen using three ground motions corresponding to different hazard levels. Lateral displacement and base shear demands were measured. The crack propagation at the base of the dam was monitored with the measurement of the crack widths and the base sliding displacements. After the pseudo-dynamic loading, a static pushover test was conducted to determine the reserve capacity of the test specimen. Despite major cracking at the base of the monolith, neither significant sliding nor a stability problem that might jeopardize the stability of the dam was observed. Copyright © 2015 John Wiley & Sons, Ltd.

In addition to high seismicity, poor construction quality, incorrect detailing and structural mistakes in Turkey have caused enormous loss of life and property. Therefore, seismic rehabilitation has been a major topic for civil engineers in Turkey. The object of this research is to develop a simple method that will provide strengthening of buildings without evacuating the inhabitants. This study is based on application of steel-fibre-reinforced mortar on masonry infill walls with the aim of converting nonstructural partition walls into load-carrying walls. The specimens were one-third scale, two-storey, single-bay reinforced concrete frames with hollow brick masonry infills. The main variables were the ratio of fibre (0% and 2%), fibre reinforced mortar thickness (0, 10 and 20 mm), existence of anchorage (non-anchored or anchored) and type of fibres (steel fibre, polypropylene fibre or hybrid fibre). Strengthening by the application of steel-fibre-reinforced mortar on infill walls of frames retarded the early out of plane failure of the walls and converted the existing non-structural walls into load-carrying walls, so that the strength, stiffness and energy dissipation capacity of the frame increased significantly.

Canbay, Erdem/0000-0001-6798-0144; Baran, Mehmet/0000-0001-6674-7308 WOS: 000313559600005 Strengthening the existing hollow brick infill walls by bonding high-strength precast concrete panels or applying steel fibre reinforced mortar was found to be an occupant-friendly seismic retrofitting technique for the buildings in use with deficient reinforced concrete structural systems. Both techniques convert the existing non-structural hollow brick infill walls into load-carrying structural members. To verify the effectiveness of the techniques, 20 reinforced concrete frames with hollow brick infill walls were tested under reversed cyclic lateral loading simulating earthquake. In the present study, hollow brick infill walls strengthened by these techniques were modelled by means of two equivalent diagonal struts in the analytical studies. Analytical results matched well with the experimental results. A performance-based rehabilitation case study of an existing building showed that both techniques offer a sound and practical solution for rehabilitation studies.

Six real-size beams were tested in order to examine the reliability of tension lap splices for the minimum requirements of clear cover, spacing between bars and transverse reinforcement. The beams were prepared in accordance with the minimum provisions of the American Concrete Institute building code requirements for structural concrete (ACI 318–08) and the Turkish standards on requirements for design and construction of reinforced concrete structures (TS 500). Results showed that all beams prepared in accordance with ACI 318–08 showed satisfactory behaviour. Since the specimen prepared according to TS 500 with 26 mm diameter bars failed due to bond, it can be concluded that the TS 500 clear cover is insufficient for spliced bars equal to or greater than 26 mm in diameter. In order to evaluate the ACI Committee 408 new proposal and Eurocode 2 provision for tension lap splices, a case study was also conducted. According to the results of the case study, while the ACI 318–08 requires unnecessarily longer splice lengths for bars of greater than 19 mm diameter, Eurocode 2 always gives the smallest lap splice length which leads to safety concerns.

There is an excessive demand for the rehabilitation of frame-type RC buildings which do not satisfy current seismic code provisions. Therefore, it is imperative to develop user-friendly strengthening methodologies which do not necessitate the evacuation of the building during rehabilitation period. The aim of this study was to strengthen the masonry infill walls by means of diagonal carbon fiber-reinforced polymer fabrics and to integrate them with the existing structural frame in order to form a new lateral load resisting system. This study investigated the possible effects of height-to-width ratio of the infills on the overall behavior attained by the previously developed rehabilitation methodology. In the first part of the study, eight 1/3 scaled, one-bay, two-story RC frames with two different aspect ratios were tested. The experimental results in terms of lateral stiffness, strength, drift, and energy dissipation characteristics of the specimens were discussed. In the second part, a numerical study of the frames was conducted to estimate the non-linear behavior of the specimens.

In this study, seismic retrofitting of undamaged and moderately damaged RC columns with CFRP was investigated. The experimental program was conducted on five RC columns with inadequate tie spacing, 90-degree hooks at tie ends, and plain (undeformed) reinforcing bars. Columns were tested under a constant axial load of 27% of axial capacity and under reversed lateral cyclic loading. The primary objective of this study was to investigate the influence of sustained axial load during repairing, damage, and corner-rounding radius of CFRP wraps on the seismic performance of RC columns. Improved performance in terms of ductility, dissipated energy, and secant-stiffness degradation was observed for the CFRP strengthened columns. Reducing the corner-rounding radius deteriorated the seismic behavior of the columns, while the stiffness degradation response remained unaffected. The sustained axial load during repairing had only minor effect on column behavior. After CFRP repairing, the increase in yield drift ratio and curvature was observed to be in proportion with the corresponding consumed ductility values during damage cycles. A drift-based design equation for FRP repaired columns was proposed that considers the damage amount and axial load level as the major parameters as consistent with the experimental results.

The code provisions on lap splices are critically assessed in the light of 203 beams without transverse reinforcement and 278 beams with transverse reinforcement. For comparison, the provisions given in the ACI 318, Eurocode 2, and TS 500 Codes are considered. The ACI Committee 408 recommended provision and a new proposal are also taken into account throughout the assessment. The comparison with real beam tests where the splice region was subjected to constant moment indicates that current provisions in the Codes do not agree acceptably with test results. The steel stress prediction graphs calculated by means of the Code provisions show high scatter and remain unsafe especially for test data without transverse reinforcement. Both the recent recommended provision by ACI Committee 408 and a new design expression proposed by the author have much less scatter with fewer unsafe predictions. The simplified design provision proposed by ACI Committee 408 does not yield similar results to that of the advanced design provision proposed by the same committee and therefore it could conveniently be replaced with the simpler equation proposed by the author.

The behavior of high strength concrete tied columns was investigated. A total of 11 columns were tested under monotonic loading having two different eccentricities. The main variables investigated were: (1) the mechanical ratio, (2) the spacing, and (3) the configuration of transverse reinforcement. Test results indicate that, under monotonically increasing axial load, the cross ties with a 135 degrees hook at one end and 90 degrees bent at the other end provide ductility comparable to ties supporting the intermediate longitudinal bars. Also the use of four different equivalent rectangular stress blocks (ERSBs) in predicting the ultimate strength of members made of high strength concrete was evaluated. It is concluded that calculations made using the ACI 318-02 stress block always gives an upper bound, whereas a lower bound is obtained by the CSA A23.3-94 approach. Capacities calculated using the ERSB proposed by Bae and Bayrak, and Ozbakkaloglu and Saatcioglu also agree quite well with the test results.

The design, manufacture and calibration of two special force transducers, capable of measuring the axial force, shear, and bending moment at the base of a structural column are presented. The special force transducers were fabricated to measure the reactions at the base of the exterior columns of a reinforced concrete three-bay, two-story test specimen. The force transducers had the following capacities: 35 kN for axial load, 4 kN for shear, and 3 kN m for bending moment. These values include a safety factor of 2.0. Each force transducer was composed of six independent load cells. Four of these load cells were placed vertically and the other two diagonally. In total, eight calibration tests were conducted on each of the two transducers to form a calibration matrix for converting the six load cell readings into three reaction components. The results of the calibration procedure were very successful with the differences between the applied and calculated values generally less than 2%. The two force transducers were subsequently used in a frame test and they provided an excellent way to measure the internal forces without significantly affecting the overall behavior of the structure.

In the last decade, a new strengthening methodology has been developed for reinforced concrete (RC) frames with hollow clay tile (HCT) infill walls by means of diagonally applied carbon fiber–reinforced polymer (CFRP) fabrics. In the experimental part of a study conducted by the authors, this user-friendly methodology was experimentally investigated considering different aspect (height/width) ratios of the infill walls. In this study, first a numerical model of the FRP strengthened infill walls strengthened with the proposed methodology is developed. Afterwards, the numerical simulation results are validated by use of experimental response curves and finally, a parametric study, which further investigates the effect of aspect ratio of HCT infill walls is presented.