Ibrahim Erdem

Analytical Investigation of Lateral Strength of Masonry Infilled RC Frames Retrofitted with CFRP

In this study, two reinforced concrete frames with hollow clay tile masonry infill walls, retrofitted with diagonally applied carbon fiber-reinforced polymer (CFRP), which were tested previously, were analytically investigated. A simple material model for the masonry infill wall strengthened with CFRP is suggested. The lateral strength of each rehabilitated frame was obtained by pushover analysis of four different models using a commercially available finite-element program, and the results were compared with the test results. We also determined the lateral strength of the CFRP-applied masonry infill walls, and compared the results with the results obtained from existing analytical models. Drift capacity of the masonry infill walls strengthened with CFRP was also investigated, and the drift capacity of the masonry infill walls strengthened with diagonally applied CFRP was recommended. It is concluded that the strength of the masonry infilled frames strengthened with diagonally applied CFRP can be satisfactorily predicted with the suggested procedure. The ultimate drift capacity of the masonry infill walls strengthened with diagonally applied CFRP strips was conservatively predicted to be 1.0%.

Simulation of the behaviour of the L1 vertebra for different material properties and loading conditions

Three-dimensional finite element models of the thoracolumbar junction (T12–L2) and isolated L1 vertebra were developed to investigate the role of material properties and loading conditions on vertebral stresses and strains to predict fracture risk. The geometry of the vertebrae was obtained from computed tomography images. The isolated vertebra model included an L1 vertebra loaded through polymethylmethacrylate plates located at the top and bottom of the vertebra, and the segment model included T12 to L2 vertebrae and seven ligaments, fibrous intervertebral discs and facet joints. Each model was examined with both homogeneous and spatially varying bone tissue properties. Stresses and strains were compared for uniform compression and flexion. Including material heterogeneity remarkably reduced the stiffness of the isolated L1 vertebra and increased the magnitudes of the minimum principal strains and stresses in the mid-transverse section. The stress and strain distributions further changed when physiological loading was applied to the L1 vertebra. In the segment models, including heterogeneous material properties increased the magnitude of the minimum principal strain by 158% in the centre of the mid-transverse section. Overall, the inclusion of heterogeneity and physiological loading increased the magnitude of the strains up to 346% in flexion and 273% in compression.

A Comparative Study on the Strengthening of RC Frames

In order to improve the behavior of buildings and in order to prevent total collapse, necessary amount of strengthening must be provided. The frame of the test specimen (1/3 scaled, 2-story, 3-bay) is detailed such that it has the common deficiencies of existing buildings in Turkey. Two types of strengthening techniques, namely introducing an infill RC wall, and CFRP strengthened hollow clay tile wall, are investigated. The test specimens are subjected to reversed cyclic quasi-static loading. By means of special transducers, axial force, shear force and bending moment at the base of the exterior columns are measured. Strength, stiffness, and story drifts of the test specimen are determined.

Challenges in Renovation of Vintage Buildings

AbstractStructural engineers often encounter various unique design and construction challenges during renovations of vintage buildings. If such challenges are not properly addressed, they may result in major consequences. This paper provides a case study of a flawed structural renovation project and discusses the common challenges that engineers may face during renovation projects. The subject building is a six-story vintage residential building with a structure consisting of exterior load-bearing brick masonry walls, interior cast iron and wood columns, and wood floor framing. The renovation project mainly included the addition of a penthouse, addition of a freestanding fireplace and chimney, and converting a roof into a roof garden for the owner of the top story of the building. Due to several serious structural issues that were discovered during and after the renovation project, the penthouse, fireplace, and chimney had to be demolished, and usage of parts of the apartment was restricted to prevent str...

Survey of Stair Construction Codes in New York City

Forensic investigations of slip, trip, and fall incidents on stairs often involve the study of the applicable codes and standards that were in effect at the time of construction, at the time of subsequent renovation, and at the time of the incident. Similarly, the rehabilitation of existing stairs following a fire, flood, or collapse, as well as the change in building use, or change in occupancy, may prompt a similar study. Navigating the various editions of the codes and design parameters can be challenging. This paper aids in that effort. This paper surveys the Building Codes of the City of New York, its adopted reference standards, other related industry standards, and is a guide for navigating the historical editions and identifying the various provisions pertaining to the design parameters, such as illumination, signs, headroom, slip resistance, guards, handrails, doors, landings, and treads and risers, etc.

BEST PRACTICES FOR CONDUCTING PRE-CONSTRUCTION SURVEYS: LESSONS LEARNED FROM CONSTRUCTION CLAIMS

Demolition, excavation, and construction that are performed in close proximity to existing buildings and structures, and in particular those in an urban environment, may cause damage to the surrounding structures ranging from the loss of serviceability to complete collapse. In these instances, disputes often arise over the cause and the extent of the damage and also the roles and responsibilities of the contractors engaged in the work. A forensic investigation of the alleged damage, and in particular, the cause and the extent of the damage and a determination of new versus pre-existing damage after the construction has begun, or after it has been completed, can be challenging. One approach is to compare the alleged damage with those conditions, or the lack of conditions, identified in the pre-construction survey report. This paper surveys the industry literature on the code requirements for conducting pre-construction surveys, practices for conducting condition surveys used in the assessment and the rehabilitation of existing structures, and types of damage and the causes of that damage that are often alleged in construction claims arising from adjacent construction. This paper also compiles some of the best practices for conducting pre-construction surveys and for reporting the findings. These practices are taken from the lessons learned from actual construction claim disputes.