General Perspectives on Seismic Retrofitting of Historical Masonry Structures

This chapter focuses on retrofitting of historical masonry structures from the point of seismic resistance based on failure analysis. In historical structures, restoration applications have become necessary because their life cycle of structural and nonstructural members is completed due to natural result of material structure, environmental conditions, and/or user errors. One of the most important intervention decisions in restoration stages carried out in historical buildings is known as retrofitted of the structure. The choice techniques of retrofitting of the structural members are becoming a very important issue in the scope of restoration of historical masonry structures belonging to the cultural heritage. Additionally, it should be decided to optimally preserve such buildings’ original forms and to make interventions to increase the building’s service life; in this regard, it is important to preserve the structures’ historical identity and constructional value. Therefore, retrofitting applications have become essential to prevent the damage level and to have adequate level of structural strength in order to resist dynamic effects such as earthquakes. In this chapter, it is aimed to determine the main principles by using conventional and modern techniques within the scope of laboratory tests and numerical approaches in recovering the historical structures

Structural damage caused to RC buildings by tunnelling work

Nagli pomaci u tlu mogu dovesti do oštećenja armiranobetonskih građevina. Takvi pomaci mogu između ostalog biti uzrokovani gradnjom tunela, pa se utjecaj takve gradnje treba uzeti u obzir u postupku projektiranja građevina. U ovom se radu na primjeru postojeće bolničke zgrade analiziraju konstrukcijska oštećenja armiranobetonske građevine uslijed naglih pomaka tla. Kako bi se dobili što točniji podaci za potrebe analiza, primijenjen je multidisciplinarni pristup radi povezivanja raznih inženjerskih disciplina koje su sudjelovale u ovom istraživanju.Structural damages to RC (Reinforced concrete) buildings occasionally occur as a consequence of sudden ground movements. One of these is effect of tunnel excavation on the structures and the design process should be carried out by taking the effect into account. In this study, the structural damages caused by the impact of sudden movement emanating at the ground were investigated for a selected hospital building. Within the scope of this study, it was aimed to obtain the most accurate data by combining different engineering disciplines through a comprehensive approach

Seismic load tests on exterior beam-column connections of existing RC structures

U radu su izneseni prijedlozi za poboljšanje svojstava spojeva greda-stup postojećih AB konstrukcija uslijed potresnog djelovanja. Analizirana je uporaba betona niske čvrstoće, glatkog armaturnog čelika bez spona u spojevima te je ispitano ponašanje spojeva u uvjetima pod cikličnim opterećenjem. U okviru eksperimentalnog istraživanja proizvedeno je i ispitano pet uzoraka s različitim rasporedom armature. Na temelju rezultata zaključeno je da su kritični parametri koji određuju svojstva postojećih konstrukcija, raspored spona u spojevima i upotreba kuka za sidrenje uzdužne armature koje su savijene pod kutom od najmanje 90°.Suggestions for improving seismic performance of beam-column connections of the existing RC structures are presented in this paper. The use of low-strength concrete with plain bars without stirrups in joints is analysed, and behaviour of joints in the aforementioned conditions under cyclic load is investigated. Five specimens with different reinforcement configurations were produced and tested in the experimental process. Based on results, it was concluded that critical parameters for the performance of existing structures are: stirrup arrangement in joints, and the use of at least 90-degree hooks in longitudinal reinforcement of beams

The conservation and repair of historical masonry ruins based on laboratory analyses

Historical masonry structures that remained under the ground due to settlement have to be revealed and preserved because of their historical values. The study focuses on assessment of wall ruin from early Byzantine period and the arched vault ruin from Ottoman period. In this study, the properties and problems of the materials as mortars and woods were analyzed, which were gathered from the ruin structure wall, vault, brick pipe and bonding wood. The study consists of the on-site examination, laboratory analyses and application proposals about the wall ruin from early Byzantine era and arched vault ruin from Ottoman era which were unearthed during the re-construction of education building. In the first stage of study, representative samples taken from different locations of the masonry ruin were exposed to chemical- and mineralogical-analyses, and the content of samples were determined. In the second stage, the data of analysis were assessed, then the conservation and repair proposals were submitted for implementing on the masonry ruin. By proposed materials for the conservation, it will not be occurred mechanical stresses due to the original and new repair mortar- and wood-materials have the similar physical and mechanical properties. Thus, this will lead to long and healthy life to the original materials of the ruin structure. (C) 2016 Elsevier Ltd. All rights reserved

Damage Assessment of RC Flat Slabs Partially Collapsed Due to Punching Shear

The aim of this study is to determine the causes of brittle collapse of existing reinforced concrete (RC) flat slab supported by columns under vertical loading. This paper focuses on the assessment of RC flat slab structures from the point of punching shear resistance. The entire process is illustrated using a case study from a parking structure. In the examined structure, the second storey slab was collapsed to the first storey slab without any earthquake and impact effects. A partially collapsed RC flat slab structure is examined within the scope of a field survey, lab studies, and numerical analyses. The first stage of the study examines the existing state of the collapsed structure and its compliance with architectural and structural drawings. Second, mechanical tests are conducted on samples gathered from the structure, based on observational research and lab environment. At the final stage, the structure's three-dimensional finite element model is prepared and the causes of the collapse of the structure are determined. The analysis shows that the lack of shear reinforcement, unforeseen loadings, and design errors are remarkably harmful to the slab-column connection resulting in punching shear resistance

Characterization of ground slag and borax waste and their effects on the compressive strength of briquettes

The usage of briquettes is preferred in the construction industry for many years. The quality of briquettes is directly related with characteristic features of raw materials and their compositions, production procedure, firing method, temperature and duration. There are waste materials such as borax waste having been used for briquette production, however it is not available to combined of both borax and ground slag used in briquette production. In the study, both borax and ground slag were used together as an additive in order to observe effects on the material characteristics of briquette samples. In this scope, compressive strength and bulk density of the samples produced using borax and ground slag were defined. Moreover, SEM-EDS, XRD and DTA/TG analyses of the materials were carried out and discussed. The overall results have concluded that not only higher compressive strength results were obtained using these wastes, but also the usage of waste up to 22% ratio was provided for this study. Consequently, it is determined to be possible using borax waste and ground slag in briquette production. (C) 2016 Elsevier Ltd. All rights reserved

Structural damage caused to RC buildings by tunnelling work

Nagli pomaci u tlu mogu dovesti do oštećenja armiranobetonskih građevina. Takvi pomaci mogu između ostalog biti uzrokovani gradnjom tunela, pa se utjecaj takve gradnje treba uzeti u obzir u postupku projektiranja građevina. U ovom se radu na primjeru postojeće bolničke zgrade analiziraju konstrukcijska oštećenja armiranobetonske građevine uslijed naglih pomaka tla. Kako bi se dobili što točniji podaci za potrebe analiza, primijenjen je multidisciplinarni pristup radi povezivanja raznih inženjerskih disciplina koje su sudjelovale u ovom istraživanju.Structural damages to RC (Reinforced concrete) buildings occasionally occur as a consequence of sudden ground movements. One of these is effect of tunnel excavation on the structures and the design process should be carried out by taking the effect into account. In this study, the structural damages caused by the impact of sudden movement emanating at the ground were investigated for a selected hospital building. Within the scope of this study, it was aimed to obtain the most accurate data by combining different engineering disciplines through a comprehensive approach

Seismic retrofitting of the historical masonry structures using numerical approach

In historical buildings, because of the deterioration on structural members including slab and walls that complete their life cycle in time, due to environmental conditions; restoration applications have become necessary to increase the material durability level and to have adequate level of structural strength in order to resist dynamic effects such as earthquakes. This paper focuses on assessment of historical masonry structures from the point of seismic resistance. The entire process is illustrated using case study from a historical masonry structure. In this study conducted in this respect, a historical building is restored within the scope of laboratory studies and numerical analyses. The first stage of the study includes plaster analyses and mechanical tests conducted on the samples taken from the said building. In the second stage, i.e. numerical analysis, the building's existing 3D computer model was prepared and materials, members that are inadequate in terms of strength were determined. The third stage includes restoration applications by using laboratory and numerical analysis results. Within the scope of restoration applications, structural cracks on the walls were repaired using the injection method; volta slab (brick floor arches), exterior facade walls, interior walls and door/window gaps using different techniques were strengthened. In this study, it was aimed to increase material durability and structural strength by using conventional and modern techniques within the scope of laboratory tests and numerical approaches in recovering the historical buildings. (C) 2016 Elsevier Ltd. All rights reserved