Eray Baran

Damage in Reinforced-Concrete Buildings during the 2011 Van, Turkey, Earthquakes

AbstractTwo major earthquakes with magnitudes Mw=7.2 (ML=6.7) and ML=5.6 occurred in eastern Turkey on October 23 and November 19, 2011. The maximum measured peak ground accelerations for the two ground motions were 0.18g and 0.25g, respectively. The earthquakes resulted in various levels of damage to RC moment-resisting frame buildings ranging from minor cracking in brick partition walls to total collapse. This paper summarizes the field observations of the Atilim University Reconnaissance Team carried out in the region a few days after the two main shocks with an emphasis on the performance of RC buildings. A summary of the evolution of the Turkish seismic design code during the last 35 years is given, followed by an explanation of the behavior of RC buildings during the October 23 and November 9 earthquakes. The deformation types that were commonly observed in the heavily damaged or collapsed RC buildings include plastic hinging in columns attributable to stiffer beams, localization of damage in ground...

Flexural Strength Design Criteria for Concrete Beams Reinforced with High-Strength Steel Strands

This paper summarizes the result of a study investigating the flexural behavior of concrete beams reinforced with high-strength prestressing strands. Thirteen concrete beams reinforced with either conventional reinforcing bars or high-strength strands were fabricated and load tested in the experimental part of the study. No distinct difference was detected between the experimentally obtained cracking patterns of the two groups of beams. For the same reinforcement amount, beams reinforced with high-strength strands exhibited slightly smaller service stiffness than those reinforced with conventional reinforcing bars. A comparison of the measured and numerically predicted response of beam specimens indicated that the cracking load, peak load, and the deformation capacity of concrete beams can be accurately determined by a sectional analysis procedure for both types of reinforcement. The level of ductility present in concrete beams reinforced with high-strength strands is evaluated using the parameter called “displacement deformability ratio.” Using the numerically determined maximum reinforcement limits for concrete beams reinforced with high-strength strands, an expression was proposed to be used at the design stage.

Experimental Determination of Resistance Characteristics of Support Details Used in Prestressed Concrete Bridge Girders

Static load tests were performed on support details used at the ends of prestressed concrete pedestrian bridge girders to determine the resistance characteristics of girder supports in the direction perpendicular to the longitudinal axis of the girders. The specimens tested represent support details that have also been widely used in prestressed concrete highway bridges in Minnesota and in other states. Two specimens, one representing the free-end detail and one representing the restrained-end detail were subjected to a combination of vertical and lateral loads. The applied loading was intended to simulate the loading conditions to which the girder ends would be subjected in the event of an over-height vehicle collision with the bridge. The tests revealed two types of lateral load resisting mechanisms depending on the type of support detail. The specimen with the free-end detail resisted the lateral loading through sliding friction between the components of the support assembly. Deformation of this specimen was a combination of shear deformation of the bearing pad and sliding of various support components. The restrained-end detail exhibited larger lateral load capacity than the free-end detail due to the resistance provided by the anchor rods that were intended to prevent the lateral movement of the girder ends. Failure of the specimen with restrained-end detail was due to the concrete breakout and bending of the anchor rods.

Performance of a Prestressed Concrete Pedestrian Bridge System under Equivalent Static Lateral Impact Loads

The resistance of prestressed concrete through-girder (PCTG) pedestrian bridges to lateral loads was studied in response to the increasing number of vehicular impacts in the United States. This research was motivated by the lack of reported studies analyzing the behavior of such bridges to lateral impact loads, as well as their potential vulnerability in comparison with bridges that are better able to redistribute and transfer locally applied impact loads through alternate load paths. Pedestrian bridges are of lighter construction than highway bridges and they do not have the high degree of redundancy, making them more vulnerable to collapse in the event of vehicular impact. Results from static lateral load analyses using three-dimensional, geometrically nonlinear, full-scale finite element (FE) models of a typical bridge system and bridge subassemblages were used to evaluate the characteristics of the system. The FE models were calibrated with experimental test data on typical subassemblages and connection details for PCTG bridges. Results of the experimental part of the program have already been published elsewhere. This paper summarizes the observations obtained from nonlinear static FE analyses of a PCTG pedestrian bridge system subjected to lateral impact loads. The analyses indicated that the location of impact, the type of connector, and the flexibility of the end support details affected bridge performance. Improved connection details are suggested for enhanced PCTG pedestrian bridge performance.