Enter your email address to follow this blog and receive notifications of new posts by email. It is due to the water column resting on the upstream sloping side. Why response spectral matching should be done with target spectrum in time history analysis in ETABS? In order to calculate the Vz the following expression is used, k1 = Risk coefficient k2 = Coefficient based on terrain, height and structure size| k3 = Topography factor. Compressive strength test on Building materials, Quality check of building materials on site, Floors in houses, hospital wards, dormitories, Shops, educational buildings, assembly buildings, restaurants, office floors for storage, assembly floor space without seating, public rooms in hotels, dance halls, waiting halls, Stairs, landings, balconies and corridors for floors but not liable to overcrowding, Stairs, landings, balconies and corridors for floors liable to overcrowding. Law of Interaction C. Law of Acceleration D. Law of Gravitational Force 1 See answer xenxiayoung xenxiayoung Answer: D. Explanation: law of acceleration that forces act with equal magnitude and in opposite direction. II) Water pressure below the base of the dam or Uplift pressure. On an average, a value of 500 kN/sq.m may be taken under ordinary circumstances. As per NEHRP guidelines, design response spectrum is developed from the PSHA framework. Dynamic loads created due to earthquakes must be considered in the design of all major dams located in ‘high-risk’ seismic regions, and for dams situated in close proximity to potentially active geological fault complexes. Codes of practice started (before 1970) with only the horizontal component; assuming a fraction of the total wight as a horizontal force on the structure. Thank you. Where w is the specific weight of water. Quantity of Cement and Sand Calculation in Mortar, Types of Foundation for Buildings and their Uses [PDF], Tips to Avoid Reinforcement and Embedment Congestion in Concrete Members, Thumb Rules and Specifications for Design of Reinforced Concrete Beam. "Our measurements showed that the effect is much larger than could be expected based on prior studies and allowed us to improve the existing friction laws.". Water pressure may be subdivided into the following two categories: It is the pressure of water on the upstream face of the dam. Later on they have added the vertical components. Out of these forces, most common and important forces are water pressure and self weight of the dam. The accuracy in determination of PSA is very important in calculating the final shear load. The total design base shear in a given direction is to be determined from the following Eqn. Earthquake produces waves in every possible direction. Different types of forces acts on a dam structure such as water pressure, self weight, wave pressure etc. "While discrepancy between changes in normal stress and friction has been pointed out by prior studies, it has not been clear how significant this effect is for thrust earthquakes," adds Lapusta. If you write back where, then it is easier to answer, since there might be a context to such statement. VIP members get additional benefits. Never Miss an update Click on “Allow US” and make us allow or Click on Red notification bell at bottom right and allow notifications. This force acts linearly along the length of the dam and at the reservoir level. Firstly finding someone who can tell me exactly what the code says and secondly how to debunk it. This type of loading may come and go. = 2×9.81 h²w kn/m Get weekly and/or daily updates delivered to your inbox. Designing for Earthquakes A Manual for Architects. In two dimensional analysis of the gravity dam, unit length of the dam is considered. Inertia force acts in a direction opposite to the acceleration imparted by earthquake forces. As per USBR, the total horizontal force will be 1.8h² kn/m and vertical force will be 4.6h² kn/m. Therefore, it is essential to study the nature of uplift and also some methods will have to be devised to reduce the uplift pressure value. The structure should be strong enough with the heavy dead weights and anchored to the ground to resist this wind load. I am modelling a tunnel structure (rectangular) using Soil-Structure Interaction in SAP2000. Earthquake forces : An Earthquake produces waves which are capable of shaking the dam in every possible direction. Save our Whatsapp contact +919700078271 as Civilread and Send us a message “JOIN”. ( Log Out / However, you have doubled my problem. Sloping, since it can be thought of as a dam? in time domain and in frequency domain. When the fault-normal stress ebbs, the fault is clamped less tightly in place and becomes more likely to slip, causing a quake. and Terms of Use. Law of aceleration yan anya ba a taltalaga LAW OF INTERACTION wenno LAW … I think that is sufficient coefficient for horizontal and vertical accln differ zone to zone but 0.1 to 0.2 is sufficient. The pressure diagram is triangular and the total pressure is given by. After earthquake zone has been identified, the following steps are followed: Change ), You are commenting using your Facebook account. Earthquake forces are internal forces that developed on the structure because of ground movements. Civil Read Wishes you ALL the BEST for your future.. Which model is better for soil-structure interaction in SAP 2000 joint-springs or Link element? Please enter your email address. This site uses cookies to assist with navigation, analyse your use of our services, and provide content from third parties. Earthquake wave may move in any direction and for design purposes, it is resolved into the vertical and horizontal directions. "Indeed, many destructive earthquakes occur as thrust ruptures in subduction zones, sometimes causing devastating tsunamis such as during the 2011 magnitude 9.0 Tohoku earthquake. 0.1 when 0.1g is accounted for earthquake forces. γsub = submerged unit weight of silt material. ", "The history-dependent frictional law of the fault, which is very hard to determine, is any modeler's biggest assumption," Rosakis says. Hi! Soft silty clay, silty clay, silty sand, sandy silt, sand, clay, stiff silty clay. why should we match response with specific target spectrum ? The information you enter will appear in your e-mail message and is not retained by Phys.org in any form. The live load includes the weight of furniture, people occupying the floor, etc. The total pressure is in horizontal direction and acts on the upstream face at a height from the bottom. Where you can post your queries or answer the fellow engineer queries Know more ». What are the Different Types of Underground Water Sources? It well known that the deterministic (DSHA) and probabilistic (PSHA) seismic hazard maps provide prediction of peak ground acceleration and ground motions for a specific site. In this paper, the sequence of significant developments in the methods of analysis of dynamic earthquake interaction between structures and their foundation media is outlined. Apart from any fair dealing for the purpose of private study or research, no in ETABS there are two approaches for spectral matching i.e. (b) Hydrodynamic Pressure: Horizontal acceleration towards the reservoir causes a momentary increase in water pressure. Where is the uplift pressure, B is the base width of the dam and H is the height upto which water is stored. Click here to sign in with This vertical pressure is given by. Fig.3:water pressure at down stream of a dam structure. : submerged unit weight of silt material. Snow loads are calculated by the projections made by snow at different parts of the structure, The amount of snow load depends on the height of building, size & shape of the roof, the location of building whether it’s on the slope or not, the frequency of snow etc. According to ASCE, the seismic load effect, E, is split into two parts, a horizontal effect and a. Wave pressure depends upon wave height which is given by: : height of water from the top of crest to bottom of trough in meters. An Earthquake produces waves which are capable of shaking the dam in every possible direction. Fig.2: water pressure on the inclined upstream of a dam. The design seismic forces may be assumed to act non-concurrently in the direction of each principal axis of the structure. or, by Robert Perkins, California Institute of Technology. It can be computed using the following equation: The weight of dam and its foundation is a major resisting force. ( Log Out / You may refer to pages 38 and 39 of attached PDF to see the provisions of AISC. Picture This 2. Earthquake is the most dangerous natural phenomenon that generates sizable destruction in structures. Tank you for finding a code in respond to my request. A. The upward pressure is known as uplift which is the second largest external pressure. The factor 1.2 on gravity loads effectively represents a vertical acceleration of about 0.2 x 2.5 = 0.5 times the peak horizontal ground acceleration. Pw = 2.4 γw hw and acts at hw/2 meter above the silt water surface. What are the Methods of Interpolation of Contours. The effect of earthquake is equivalent to an acceleration to the foundation of the dam in the direction in which the wave is travelling at the moment. Lost your password? Become VIP Member. part may be reproduced without the written permission. Forces Acting on Gravity Dam and Their Magnitude and Line of Action. hw = 0.032 √vf + 0.763 – 0.271 f¾, for f<32. The ice which may be formed on the water surface of the reservoir in cold countries may sometimes melt and expand. Why is the vertical component of earthquake in buildings not considered while IS 1893-1984 given for retaining wall and bridges not for building? This vertical pressure is is calculated as follow: Pressure acts through the center of gravity of the water column resting on the sloping upstream face. Vertical acceleration reduces the unit weight of the dam material and that of water is to times the original unit weight, where is the value of g accounted against earthquake forces, i.e. Seismic forces are estimated according to the following equations: and: horizontal and vertical seismic coefficient. Forces Acting on a Dam Structure and Calculations, Types of Sulphate Attack in Concrete- Influences and Sources, Understanding the Transfer of Loads from Slab to Beams.