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The October 30, 2020 Earthquake caused unexpectedly significant damage in İzmir considering its distance to the city. This paper evaluates the recorded ground motions, summarizes the performance of structures affected from the earthquake with emphasis on the reasons of damage. A detailed damage assessment was carried out by the Earthquake Engineering Research Center of Middle East Technical University to compile data on the damage of RC and masonry buildings. It was observed that majority of the damage was concentrated in the Bayraklı district due to its peculiar soil properties where many 7-10 story mid-rise RC buildings suffered heavy damage and collapse. The level of amplified ground motions combined with deficiencies of apparently non-code compliant buildings exacerbated the damage. The main reasons of damage were mainly attributed to the presence of soft stories, lack of proper detailing, poor construction quality, presence of heavy overhangs, and hence significant lack of code-compliance in essence. The influence of infill walls on seismic performance of deficient and inadequate buildings was clearly seen in this earthquake. This paper also discusses seismic code requirements in effect and their influence on the observed building performance. The recorded ground motions were compared with the code spectra to evaluate the performance of the buildings. The code response spectra were found to be well above the recorded ground motion spectra at the sites where significant damage was observed.

Samos Earthquake caused the collapse of about fifty buildings in Izmir city center, resulting in over 120 fatalities. The response spectra of the ground motions at the soft soil sites in Izmir revealed that the spectral accelerations in the period range of 0.5-1.5 s are similar to the spectral accelerations defined by the response spectrum corresponding to the 72-year return period. Despite experiencing accelerations lower than those defined by the Turkish Code design spectrum (475-year return period), significant damage was observed due to the deficiencies of the building stock. Several factors such as soft story, lack of code-compliant transverse steel reinforcement, and low concrete strength have contributed to the devastating loss. Studies in the last two decades on deformation capacity estimation of RC columns showed that key parameters for collapse drift limits are the axial load ratio (i.e., axial force demand to capacity ratio) and transverse reinforcement amount. Most of the collapsed buildings in the past Turkish earthquakes had low concrete strength resulting in high column axial load ratios with limited drift capacity. In order to identify the collapse of vulnerable buildings, a simple procedure is proposed based on vertical and lateral pushover analysis results. The method relies on estimating the average axial load ratios of the most critical columns and their seismic drift demands. An axial load ratio-drift demand limit state model was developed to identify the buildings with high collapse risk. The model was validated with the damaged buildings in Izmir after the Samos earthquake to capture the buildings with poor performance even under service level earthquakes. The proposed model is practical as it only requires the floor plan and concrete compressive strength. It is found to be legitimately accurate to identify and prioritize the buildings prone to collapse.

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.

Fiber Reinforced Polymers (FRPs) have advantages such as lightness, high strength, and suppressing corrosion risk. There is a vast amount of research on the FRP strengthening of reinforced concrete elements. However, the behavior of FRP bonded Autoclaved Aerated Concrete (AAC) beams has not been extensively investigated in the past. In this study, several experiments were conducted to explore the performance of FRP bonded AAC beams. In this scope, unidirectional single layer carbon and glass fiber laminates with half or full of the beam width were bonded to the AAC. Test results were mainly evaluated by comparing the stiffness, strength, ductility, energy absorption capacity, and the cost of materials. Additionally, a numerical study (based on section analysis and finite element simulation) was conducted to estimate the load-deformation response of the specimens. Based on the analysis results, effective FRP strains were evaluated and compared with the recommendations given in the ACI 440.2R design guidelines for FRPs bonded to reinforced concrete. According to the limited test data, a 60% reduction appears to be appropriate while computing the effective FRP strains for FRP bonded AAC beams. (C) 2021 Elsevier Ltd. All rights reserved.

Autoclaved aerated concrete (AAC) walls are commonly used as infill walls in reinforced concrete frames. Thermal properties of infill walls in cold regions can be improved by bonding additional insulation panels. In this study, eight half-scale, one-bay, one-story reinforced concrete frames with insulated AAC infill walls were tested under cyclic increasing in-plane (IP) displacement excursions to simulate earthquake demands. Two different methods of insulation arrangements were studied by using mineral-based cementitious materials. In addition to in-plane loading, out-of-plane (OOP) and combined in-plane and out-of-plane (IP + OOP) tests were conducted under constant axial load and increasing cyclic displacement excursions. It was observed that insulated AAC infill walls had limited deformation capacity with premature failure of the insulation plates. The observed damage limits of the insulated AAC infills were compared with the codes' drift ratio limits. It was concluded that such walls should be classified as fragile components with limited drift capacity.

Infill walls in reinforced concrete frames are susceptible to failure owing to their brittle nature. Their interaction with boundary columns during earthquakes may also cause shear damage in the columns. It is crucial to employ effective seismic strengthening strategies in order to mitigate the seismic risk induced by the infill walls. In this study, a new strengthening technique, conducted by bonding engineered cementitious composite (ECC) precast panels onto infill walls, was investigated. Three reinforced concrete frames, termed bare frame, infilled frame and strengthened frame, were tested by using the pseudo-dynamic testing method. The test specimens were three-storey, three-bay, half-scaled frames with the central bay having hollow clay brick infill walls. The specimens were subjected to three consecutive ground motions scaled to represent earthquakes with return periods of 144, 475 and 2475 years. The experimental results were compared to observe the influence of the infill walls on the reinforced concrete frames, and to demonstrate the performance of the proposed strengthening technique. It was found that application of ECC panels significantly increased the frame strength and stiffness while allowing the system to have a displacement ductility of about four.

The seismic behavior of unreinforced masonry (URM) structures has usually been investigated by conducting laboratory tests. Such efforts, although useful in order to understand the response...

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.

Laboratory testing, although necessary to understand failure mechanisms of individual masonry walls, spandrels or small scale building models, cannot fully mimic the real system behavior of masonry structures. In order to observe the performance of an existing two story masonry structure, cyclic lateral load testing up to near collapse was conducted. The test building was sliced approximately in the middle through the reinforced concrete slabs of both stories and one side was strengthened with the objective of obtaining a strong reaction wall. The other side of the structure was taken as the test structure with a floor plan of approximately 10 m × 10 m. Hydraulic actuators attached at the slabs of both stories were employed to impose one way cyclic displacement excursions. Flexural and shear deformations on a number of walls were measured and crack propagations were monitored. The structure was tested up to a lateral strength drop of approximately 20 % from the ultimate load, which occurred at a drift ratio of about 0.60 %. The failure of the walls in the building, which were mostly failed in a diagonal tension mode, was concentrated on the first story. Results of this valuable test provide important data on the performance of an actual masonry building and were employed to assess the applicability of various stiffness and strength and simplified load-deformation models in the literature.

The diagonal application of Carbon Fiber-Reinforced Polymer fabrics on hollow clay tile infill walls has been qualified as an efficient rehabilitation method for deficient reinforced concrete frames. However, majority of the experimental studies were conducted on 1/3-scaled RC frames and the effect of specimen scaling has not been questioned. In the current study, the results of an experimental campaign on 1/2-scaled RC frames are presented. Test specimens are grouped in two series having two different aspect ratios. In each series, there are two RC frames having hollow clay tile infill walls with/without CFRP reinforcement. The results of 1/2-scaled specimens are compared with the experimental results obtained from 1/3-scaled frames. In addition, the numerical model which were developed by the authors for 1/3scaled frames are employed for modeling 1/2-scaled specimens and the results were assessed by comparing with the test results. BAP

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.

Seismic performance assessment of existing buildings requires the existing material’s properties to be determined as this has a significant influence on the seismic risk. As one of the most...

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.

The seismic behavior of a 1/2 scaled, three-story three-bay RC frame with masonry infill walls was studied experimentally and numerically. Pseudo-dynamic test results showed that despite following the column design provisions of modern seismic codes and neglecting the presence of infill walls, shear induced damage is unavoidable in the boundary columns. A finite element model was validated by using the results of available one-story one-bay frame tests in the literature. Simulations of the examined test frame demonstrated that boundary columns are subjected to shear demands in excess of their shear capacity. Seismic assessment of the test frame was conducted by using ASCE/SEI 41-06 (2006) guidelines and the obtained results were compared with the damage observed during experiment. ASCE/SEI 41-06 method for the assessment of boundary columns was found unsatisfactory in estimating the observed damage. Damage estimations were improved when the strain limits were used within the plastic hinge zone instead of column full height. TUBITAK TUBA-GEBIP program

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.

An earthquake of MW = 6.1 occurred in the Elazig region of eastern Turkey on 8 March 2010 at 02:32:34 UTC. The United States Geological Survey (USGS) reported the epicenter of the earthquake as 38.873°N-39.981°E with a focal depth of 12 km. Forty-two people lost their lives and 137 were injured during the event. The earthquake was reported to be on the left-lateral strike-slip east Anatolian fault (EAF), which is one of the two major active fault systems in Turkey. Teams from the Earthquake Engineering Research Center of the Middle East Technical University (EERC-METU) visited the earthquake area in the aftermath of the mainshock. Their reconnaissance observations were combined with interpretations of recorded ground motions for completeness. This article summarizes observations on building and ground damage in the area and provides a discussion of the recorded motions. No significant observations in terms of geotechnical engineering were made. The major tectonic structure in Turkey is the north Anatolian fault zone (NAFZ), with right-lateral faulting extending from Istanbul in the west to Karliova in the east. During the twentieth century this fault zone has produced several large earthquakes ( MS > 7) with surface rupturing with a westward migrating sequence as demonstrated in Figure 1 (Barka 1996; Utkucu et al. 2003). Around the Karliova region, NAFZ joins the southwest-trending east Anatolian fault zone (EAFZ). The EAFZ is predominantly left-lateral strike-slip in nature, but its faulting is less continuous and less localized than that of the NAFZ (Ambraseys 2009). The EAFZ has nucleated relatively small magnitude earthquakes in the twentieth century (Figure 1). Recent GPS data indicates that the slip rate in the EAFZ has an upper bound of 8±1 mm/year (Ambraseys 2009). The epicenter (by USGS) of the 8 March 2010 Elazig-Kovancilar earthquake is in the segmented fault region …

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.

To provide increased insight regarding the bond behavior of fiber-reinforced polymer (FRP) bars, 41 glass FRP, carbon FRP, and steel reinforced concrete beams with unconfined tension lap splices were tested. The test results are analyzed to evaluate the influence of splice length, surface deformation, modulus of elasticity, axial rigidity, and bar casting position on bond strength. Furthermore, the test results are compared with the current design expression recommended by ACI Committee 440 to evaluate its applicability. This comparison clearly indicates that the current design expression is inadequate, and that a new design equation is needed. More importantly, however, this research sheds light on the importance of the axial rigidity of the reinforcement on bond strength. Test results demonstrate that bond strength is linearly related to the axial rigidity of the reinforcement. This finding has future implications regarding the development of improved design expressions and allowing for an improved understanding of bond strength.

The use of mesh reinforcement with mortar on existing brick infill walls of reinforced concrete (RC) frames is a recommended seismic strengthening procedure in the Turkish Seismic Code (2007). The premise of the method lies in its ease of application and success in eliminating the out-of-plane failure of existing infill walls. The performance of the mesh reinforced mortar (MRM) application was investigated by pseudo-dynamic (PsD) and cyclic testing. A three-story-three-bay 1:2 scale RC frame with hollow clay tile (HCT) infills in the middle bay was first tested using a continuous pseudo-dynamic test method for three synthetic ground motions compatible with the Duzce city center response spectrum. The test specimen was code complaint. No significant structural damage besides some cracking in the boundary columns was observed but the infill walls almost collapsed. After removing the infill walls of the central bay, a new HCT wall strengthened with MRM was built and the rehabilitated frame was retested under a second series of PsD and reversed cyclic loading schemes. This Chapter reports the findings of the experimental study by placing special emphasis on the seismic response of the code compliant test frame.

Pseudodynamic testing was employed to observe the seismic performance of two retrofit methods on two-story, three-bay frame structures. The test frames had hollow clay tile (HCT) infill in the central bay and incorporated the seismic deficiencies of Turkish con- struction practice, such as use of plain reinforcing bars, low-strength concrete, and insufficient confining steel. Two noninvasive and occupant-friendly retrofit schemes suggested in the Turkish Earthquake Code, namely, use of fiber-reinforced polymers (FRPs) and precast concrete panels integrated on the HCT infill, were employed. The specimens were subjected to three different scale levels of ground motion from the 1999 Duzce earthquake. The control specimen experienced severe damage at the 100% scale level and reached the collapse stage due to the loss of integrity of the infill wall and significant damage on the boundary columns. The retrofitted test structures were able to survive the highest level 140% Duzce ground motion. Test results confirmed the success of the two previously developed retrofit methods for simulated earthquake loads. DOI: 10.1061/(ASCE)ST.1943-541X.0000434. © 2012 American Society of Civil Engineers. CE Database subject headings: Pseudodynamic method; Seismic effects; Rehabilitation. Author keywords: Pseudodynamic method; Seismic effects; Rehabilitation.

A two-story, three-bay RC frame with code incompliant seismic design and detailing is tested using continuous pseudodynamic test method for three scale levels of Duzce ground motion. The ground motion produced minimum, signifi- cant, and severe damage states on the test structure. Diagonal cracking of the infill wall, column damage in the form of cover spalling and rebar buckling, and complete disintegration of the infill wall were the important observed damage events for the three scale levels, respectively. Nonlinear time history analyses were able to estimate the story displacement response with reasonable accuracy. The importance of element removal for near collapse damage state is unfolded. Tracing the local engineering demand parameters such as strains and curvature was found to be extremely difficult. (DOI: 10.1193/1.3609876)

Bilir, Turhan/0000-0003-0317-026X; Canbay, Erdem/0000-0001-6798-0144; Baran, Mehmet/0000-0001-6674-7308 WOS: 000285893300060 The objective of this research was to develop an economical, structurally effective, and practically applicable steel fiber reinforced mortar (SFRM) which could be applied onto the hollow brick infills of a reinforced concrete (RC) structure. Masonry walls were almost converted into strong and rigid infills with the application of SFRM. Two different mix proportions were produced with the composition of Portland cement, fine aggregate, water, and plasticizer or bonding agent as the chemical admixture. Tests were carried out to determine the optimum steel fiber content (1%, 2%, or 4% by volume) and to clarify the use of plasticizer or bonding agent in the mortar in the context of sticking ability, flexural, compressive, and adhesion strengths. As a result, mortar with plasticizer and 2% steel fiber (by volume) came out to be the optimum mortar mixture as strengthening material. The performance of RC frame strengthened with SFRM containing plasticizer and 2% steel fiber by volume was compared to those of the hollow brick infilled RC frame without strengthened mortar and the hollow brick infilled RC frame with reference mortar. It was observed that the specimen strengthened with the optimum mortar mix satisfied the target objectives of this study. (C) 2010 Elsevier Ltd. All rights reserved.

The accuracy of estimating the performance levels of a deficient RC frame using linear elastic and nonlinear dynamic analysis is evaluated in this study. This was achieved by comparing the response of a structure tested with pseudo-dynamic testing and estimated by the linear elastic assessment procedures along with nonlinear dynamic analysis. The test structure (three bay-two storey planar frame) is a ½ scale reinforced concrete frame having masonry infill walls in the central span. The test frame contains a number of structural deficiencies such as low concrete compressive strength (7MPa), lack of transverse reinforcement detailing at potential plastic hinge regions and beam-column joints. Tests were conducted for the NS component of 7.14 magnitudes 1999 Duzce Earthquake for three different scale levels. Test results indicated that drift deformation demands estimated using nonlinear dynamic analysis were within 15% of those observed in the tests. On the other hand, damage estimations of TEC and FEMA 356 were found to be conservative resulting in retrofit decisions. It was also observed that although nonlinear dynamic analysis provided reasonable estimations for inter-storey displacements, local demand parameters such as column curvature demands were estimated with less accuracy.

While the estimation accuracy of the strength of lap splices has been improving, the complexity of design for reinforcement development has progressively increased. This research study investigates the development of a simple and reliable design expression. Equations on development and splices of reinforcement in ACI 318-05 along with other design proposals are critically assessed in light of 203 unconfined and 278 confined beam tests where the splice region was subjected to constant moment. A simple design provision is developed that is based on a physical model of tension cracking of concrete in the lap spliced region. This new expression is shown to be consistent with current design practice, applicable to existing test results, and simple in application.

The performance of reinforced concrete structures depends on adequate bond strength between concrete and reinforcing steel. This article reports on a study of the bond strength of lap-spliced bars. The authors note that calculation methods to evaluate the strength of tension lap splices are based primarily on nonlinear regression analysis of test results. However, the results from these analyses may not be generalizable to situations beyond the domain of the data. In this study, the authors developed an expression for the calculation of bond strength based on a physical model of tension cracking of concrete in the lap-spliced region. Two different types of failure modes are considered: horizontal splitting that develops at the level of the bars (side-splitting failure), and vertical splitting that develops along the bar on the face cover (face-splitting failure). The developed expression was verified using results from 203 unconfined and 278 confined beam tests where the splice region was subjected to constant moment. Results showed that the relation between splice strength and splice length is not linear. The use of the fourth root of the concrete strength provides an improved estimate regarding the behavior of lapped splices as compared with the square root. In addition, the effect of the thickness of the concrete cover surrounding the bar is not linear.