Zdrs toplotne izolacije pod temeljno ploščo v primeru potresne obtežbe : diplomska naloga

Mikec, Janez (author), Isaković, Tatjana (mentor), Bokan-Bosiljkov, Violeta (comentor)

Glavni cilj diplomske naloge je bila študija obnašanja toplotne izolacije ekstrudiranega polistirena pod temeljno ploščo ter določitev in predvidevanje morebitnega nivoja zdrsa konstrukcijskega sklopa pri potresni obremenitvi. V laboratoriju fakultete je bila izvedena raziskava različnih konstrukcijskih sklopov toplotne izolacije: a) sedem različnih sklopov z gladko površino in b) trije sklopi z utori na zgornji strani. Utori zagotavljajo boljšo sprijemnost med temeljno ploščo ter XPS izolacijo. Na ta način lahko preprečimo morebiten zdrs in poškodbe vertikalnih inštalacij, ki potekajo skozi toplotno izolacijo. Z eksperimenti smo določili koeficiente lepenja in jih primerjali s koeficientom zdrsa ter tako ugotovili v kakšnih primerih pride do zdrsa, ko je konstrukcija obremenjena s potresno obtežbo. Koeficient zdrsa smo definirali kot razmerje strižnih in normalnih napetosti na stiku konstrukcije (temeljne plošče) in toplotne izolacije. Izpeljali smo dve enačbi za primer pritličnih stavb, s katerimi ocenimo koeficienta zdrsa, in sicer: a) za konstrukcije, katerih nihajni časi so zelo kratki in jih lahko zaradi velike togosti v primerjavi s togostjo toplotne izolacije obravnavamo kot neskončno toge ter b) bolj podajne konstrukcije, katerih nihajni časi so v resonančnem območju spektra. V obeh primerih je predpostavljeno, da na odziv ocene vpliva le ena nihajna oblika. Ugotovili smo, da se zdrs toplotne izolacije lahko pojavi še posebej v primeru stavb, katerih nihajni časi so v resonančnem območju spektra pospeškov in katerih odziv je pri potresni obtežbi pretežno elastičen. Prikazali smo tudi trend dodatnih poenostavitev enačbe za zelo (neskončno) toge konstrukcije v resonančnem območju. Končna enačba za izračun koeficienta zdrsa predstavlja hitro in enostavno orodje za projektante, ki želijo preveriti možnost morebitnega zdrsa konstrukcijskega sklopa v primeru potresne obtežbe. Za oba tipa konstrukcij smo izbrali po en značilen primer stavbe, ki smo ga projektirali v skladu z Evrokod 8 standardom ter hkrati preverili možnost zdrsa. Potresni odziv stenaste konstrukcije smo ocenili tudi s pomočjo nelinearne N2 metode. Nelinearno obnašanje se pojavi le pri izvedbi konstrukcijskega sklopa z gladko površino toplotne izolacije. Za ta primer smo izračunali ciljna pomika.

• Language: Slovenian
• Keywords: gradbeništvo, diplomska naloga, UNI, zdrs, toplotna izolacija, temeljna plošča, koeficient zdrsa, koeficient lepenja potres, inštalacijski vodi
• Work type: Undergraduate thesis
• Typology: 2.11 - Undergraduate Thesis
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [J. Mikec]
• Year: 2014
• Number of pages: XVIII, 95 str.
• PID: 20.500.12556/RUL-32487
• UDC: 699.86(043.2)
• COBISS.SI-ID: 6849377
• Publication date in RUL: 10.07.2015

Secondary language

• Language: English
• Title: Slippage of Thermal Insulation Under Foundation Slab Subjected to Seismic Load

Abstract

The main goal of the study was to determine and predict the possibility of the slippage of thermal insulation when subjected to the seismic load. The research was focused on the behaviour of insulation under the foundation slab. The experimental study of the coefficient of friction between different layers was performed at the Faculty of Civil and Geodetic Engineering. Two types of insulation were studied: a) the insulations with smooth surface, and b) with grooves on the upper side, which provided better connection between the foundation slab and insulation. We also evaluated the design formula for coefficient of slippage, which was defined for one-storey buildings and compared with the friction coefficient defined by an experimental study. The base-shear stresses were compared with the available friction stresses. It was found that the slippage of thermal insulation could occur especially when a structure has a fundamental period of vibration, which is in the resonant area of the acceleration spectrum, and the building responds essentially elastic to an earthquake load. The formula was evaluated for two examples: a) a RC wall structure, which can be considered as an infinity rigid, and b) a frame structure, whose fundamental period is in the resonant area. The simplified method is based only on the first mode of vibration. For the most common structures (wall structural systems – infinity rigid), the results, especially in a resonant area, can also be generalised and shown in a simple table, which makes them easier to use. The final equation to evaluate the coefficient of slippage represents a quick and simple tool, useful for designers in order to check a possible slippage of thermal insulation subjected to the seismic load. At the end we designed two typical construction systems (wall and frame system) by the Eurocode 8 standard. With the pushover analysis in SAP2000 and N2 method we evaluated target displacements for the insulation system with smooth upper surface. By using insulation system with grooves, total base shear of the structure does not even reach nonlinear behaviour.

• Keywords: graduation thesis, civil engineering, slippage, thermal insulation, foundation slab, coefficient of slippage, seismic load, service channels