2.1 General
Seismic evaluation and retrofitting strategies are mainly focused in this thesis. However, there are many good references that can be used as a starting point for research such as ATC40 manual for seismic evaluation and retrofitting of concrete buildings. This chapter focuses on recent contributions related to seismic evaluation and various retrofitting schemes and past efforts most closely related to the needs of the present work. For, the purpose of the present investigation, the literature is break down into following areas:
a) Seismic evaluation.
b) Retrofitting strategies.
2.2 Seismic Evaluation
This section describes previous contributions made in the field of seismic evaluation of buildings. Also, highlights various research
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1 and 21 highlights the nonlinear static pushover analysis. It is an efficient method for the performance evaluation of a structure subjected to seismic loads. Also ATC40 covers step by step procedures for pushover analysis to determine the capacity curve, capacity spectrum method and displacement coefficient method were briefly elaborated. By using these procedures this report is detailed with modeling aspects of the hinge behavior, acceptance criteria and locate the performance point. Hence, ATC40 serves as guideline for the starting of seismic evaluation process.
Federal Emergency Management Agency document 356 (FEMA356)2 contains simplified nonlinear analysis procedure (pushover analysis) to determine the displacements demand imposed on the building expected to inelastically and the conversion of the results to the capacity diagram are based only on the fundamental vibration mode of the elastic
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Model unit frames constructed for experimental investigations were 1:3 scaled models of a typical 3 m x 3 m unit ductile frame. The full size unit frame was selected from a typical 4 storied, 3-bay portal frame of a building. The seismic loading on the frame was determined using an equivalent static method. The RC frame was then analyzed for the combined effects of gravity and seismic loading and was designed and detailed according to the ACI code provisions for ductile RC frames. Pushover tests were conducted on scaled models of ductile unit frames, directly braced by X and Knee steel braces. To design the X bracing and knee-bracing systems, the excess seismic load on each frame, due to the increased elastic stiffness of the combined RC frame and bracing system, was determined and the relevant braces were designed for these excess loads. Test outcomes indicate that the yield capacity and the strength capacity of a ductile RC frame could be increased and its global displacements could be decreased to the desired levels by directly adding either an X bracing or a knee-bracing system to the frame. Steel X bracing could provide a stiffer bracing system but reduces the ductility of the ductile frame. Knee bracing could be employed to provide the desired ductility level for a ductile design. It was concluded that both X-bracing and knee-bracing systems might be used to design or retrofit for a
The earthquakes that have been considered are 1152, those for which a location was found in the catalogues: for 956 of them it was possible to calculate also, as additional information, the equivalent WA magnitude (MLBB). Indeed, since October 22, 2004 a Guralp 40-T BB seismometer with a period extended to 60 s was placed very close to the WA one. In addition, for 134 events recorded in the period 2010-2013 the equivalent ML was estimated both by the BB instruments placed at on the surface (MLBB) and at the bottom (MLTRI) of the cave (see Introduction). To compute the equivalent ML we have first deconvolved the BB instrument transfer function to obtain a ground displacement record and then we have convolved the signal with the WA transfer function.
Modulus: 1X Earth Science Name: Leroy (CHAN CHUNG YIU) Staff member in charge: Tim Dempster ID:2183820C Title: The April 1906 San Francisco Earthquake Introduction On April 18th, 1906, one of the worst natural disasters happened in the US history. This first major disaster which is recorded in human history with photography, has a 7.8 magnitude(USGS,2013).A subduction of the Pacific plates pulled into the San Andreas plates with the north-west direction, causing a 400 km(ECSC) rupture line. Huge energy is radiated out of the epicenter which was just 2 miles of west San Francisco, the intensity of the shaking nearly wiped out most of the buildings and structures with a duration of 110s(ECSC), affected around 370,000 square meters(NZH,1906).
How the Science of earthquakes was started in North America after the California Earthquake of 1906 The California earthquake of April 18, 1906 is one of the most significant earth quakes of all time. The 7.9 magnitude earthquake ruptured the northernmost 477 kilometers of the San Andreas Fault from the northwest of San Juan Bautista to the triple Junction of Cape Mendocino. The earthquake caused severe damage with reports indicating that it caused more than 3,000 deaths and destroyed more than 28,000 buildings (Borcherdt, & Gibbs, 1976).
A cloud of dust was visible from the rubble of the collapsed buildings. The only light in the city was the fire burning in the Marina district. Sirens blared from every direction. The shock was responsible for 63 deaths, 3,757 injuries and left 3,000-12,000 people homeless.
Arches are in most cases supported by wooden frame during the process of construction. Upon completing the construction process, the wooden frame is removed and both sides of the arch eventually press against the keystone which supports the arch.
Although the San Francisco Earthquake of 1906 and the Great Chicago Fire of 1871 were both horrific events that created huge destruction on the United States, they took a big toll in people’s lives in many different ways and encouraged them to take charge and rebuild back their hometowns that they loved. The San Francisco Earthquake commenced at five thirteen o’clock in the morning, with the epicenter offshore of San Francisco. The city carried more than 400,000 people during this event (Earthquake of 1906, 1). Most of the citizens who were present during the earthquake were all in bed asleep, but the early morning risers were able to witness the start of everything (The Great 1906, 5).
Not too long ago an 8.0 magnitude earthquake hit northern Chile. That earthquake caused tsunamis and landslides. A tsunami is a long high sea waves caused by an earthquake, submarine landslide, or other disturbances. A landslide is a sliding down of a mass of earth or rock from a mountain or cliff. It caused millions of coastal residents to evacuate their homes.
Disaster can strike at any moment. That is simply what we have come to expect from living in our unexpected world. In the fictional novel, The Fifth Season by N.K. Jemisin, The Stillness is a world where seismic activity is exceptionally common on a single supercontinent, caused by the increased shifting of tectonic plates and the existence of orogenes, humans who possess a unique genetic ability to control the energy from the earth. It is speculated that nature itself is punishing humanity with calamitous disasters in this world for a reason unknown to the reader. However, the effects of seismic events goes far beyond just physical destruction, both in the fictional world of the novel as well as in our real world.
The selection of ASTM A706 reinforcement bars were based on the recommendations of ACI 318-11 Code Section 21.1.5.2. The longitudinal mild steel reinforcement bars were extended in the entire column height (i.e., 104 in.). The longitudinal mild steel reinforcement bars
When was the first earthquake in North Carolina recorded? The first recorded earthquake was on March 8th, 1735 near Beth. Another one on February 21st, 1774 this one was quite noticeable speaking there were some reports from Winston Salem through Virginia. How do tsunamis form?
Assignment 2 CVE80006 Infrastructure Deterioration Modelling Concrete Crack Diagnosis Assignment The phenomenon of cracking in concrete may depend on several factors such as the amount of loading, rate of bleeding, amount of stress and strain generated in concrete, the composition of concrete and method of fabrication. The cracking of concrete has become severe due to advance construction process which demands high strength structure requiring an increase in stress, strain, and deflection resistance. The cracks in concrete are mainly classified as structural crack and non-structural crack.
I had first formal exposure to civil engineering in course “Architecture 1”. This course provided me the fundamental concepts of civil architectural principles such as designing procedure, architectural component’s layouts, functional spaces as well as environmental impacts. To strengthen my concepts I pursued the courses “Strength of Materials”, “Structural Mechanics” which gave me essential knowledge about the external and internal forces occuring in simple structural elements under action of various types of loading as well as fundamental concepts in structural analysis such as modellisation, classification of structures. I gained valuable exposure to the analysis of simple structures submitted to compound loadings by the application of the principle of superposition for such cases as: unsymmetric bending, combined bending and tension or compression, combined bending and torsion, general compound loading. Futhermore, I was fascinated by the force method and displacement method for analysis of statically and kinetically indeterminate structures.
During the early morning of the 27th of February 2010, Chile experienced the second largest earthquake in its history, and according to the US Geological Survey the fifth largest in recent history. A magnitude 8.8 on the Richter struck Chile. The earthquake lasted about two minutes and affected 75% of the total population, which are approximately 12 million people out of the total 17 million. The epicentre was about 325 southwest of the capital the Santiago, 33 kilometres below the Pacific Ocean.
Cracks are expected at intervals in this slab (Usually .90 to 1.2m) and are held together with structural steel. Appropriate spacing between cracks must be determined in order for this method to work. Continuously reinforced roads can sometimes be more expensive than the other two methods due to the higher quality of steel used in its construction, however this can be lowered by the reduced amount of cement used in the concrete mixture due to the thinner layer of concrete in comparison with the other two methods. With proper management, this method can be similar to the other two in terms of durability and cost
“Earthquakes are unique challenges for schools. Unlike other natural or man-made hazards, they occur with no warning. Schools cannot be closed in advance, nor evacuated. However, with proper training and planning in advance, everyone in your school community can be prepared to react appropriately during and after an earthquake, with appropriate supplies on hand. This lesson provides an overview of school earthquake preparedness and provides resources for use in incorporating earthquakes into your overall emergency plans (Benthien, n.d.).