Design revisions of complex building structures: work experience in Lithuania, legislative, organizational and technical aspects

This paper presents an engineering survey based on experience of the authors during design and expertise of complex building structures in period of 2000–2014. Legal, organizational and technical aspects in a procedure of changes in structural design documentation are investigated. Separate actions for implementing changes according to legislative documents in Lithuania in technical and working structural projects are presented by a general algorithm. Actual questions about sequence in proceeding with local and global analytical calculations during designing of complex structures and peculiarities of processing revised structural drawings and text documents are described in this paper. Relevance of the subject is illustrated by an example of a successful decision in solving common construction and design problems of an office building in Vilnius. Finally, conclusions and recommendations are given. This paper is an investigation of the considered problem and is designated for science researchers in civil engineering, educational and public organizations working with refinement of the design procedures and project documentation handling, and for practicing engineers

Design of people evacuation from rooms and buildings

There is a fire hazard in many civil buildings or engineering structures. Analysis of people evacuation time from the room or building is an important part of the designing process. Nevertheless, analysis of human behaviour in fire conditions is very complicated. Various factors should be evaluated, physical and even psychical, influencing safe evacuation of people from buildings. The analytical and calculating methods created are intended for analysis of people evacuation in fire conditions. Unfortunately, use of complicated calculations for determination of people evacuation requires too many resources; therefore, their application is limited. The calculation method for people evacuation presented in this paper is based on dependencies of the physical characteristics of people stream (density, intensity, movement speed) on people movement manner. The time required to evacuate people from people gathering room and building is determined in the numerical illustration of the method application. The article presents the comparison of simple calculation method and modeling with FDS+Evac software results of time for safe evacuation of people from rooms and buildings. Santrauka Daugelyje civiliniu pastatu ar inžineriniu statiniu kyla gaisro rizikos pavojus. Žmoniu evakuacijos laiko iš patalpos ar statinio analize yra svarbi projektavimo dalis. Tačiau žmoniu elgsenos gaisro salygomis analize yra labai sudetinga. Ivairūs fizikiniai ir netgi psichologiniai veiksniai, darantys itaka saugiai žmoniu evakuacijai iš statiniu, turi būti ivertinti. Išrasti analitiniai ir skaičiuojamieji metodai, skirti žmoniu evakuacijai gaisro salygomis analizuoti. Deja, sudetingu skaičiavimu metodu taikymas žmoniu evakuacijai nustatyti reikalauja pernelyg daug ištekliu, todel ju taikymas yra ribotas. Šiame straipsnyje pateikiamas žmoniu evakuacijos skaičiavimo metodas, paremtas fizikinemis žmoniu srauto charakteristikomis (tankiu, intensyvumu, judejimo greičiu), priklausomai nuo žmoniu judejimo būdo. Palyginti aprašyto ir sudetingojo žmoniu evakuacijos skaičiavimo metodu, naudojant FDS+Evac programine iranga, rezultatai. Published Published Online: 24 Jun 2011 Reikšminiai žodžiai: žmoniu evakuacija, sauga, evakuacijos laikas, FDS+Eva

Design of Deep Foundations on Bored Piles

The paper describes the design of pile foundation on the site of the Elektrenai power plant, Lithuania. The foundation is aimed to support equipment of the power plant consisting of the gas turbine, the steam turbine and the generator. Besides high loads, the equipment had a strong dynamic impact on the foundation due to its working conditions and vibration. The pilling solution was adopted due to different reasons: i) the capacity of the soil to support great stresses over it; ii) the special requirements of the main equipment about settlements, movements and stresses. Pilling foundation was evaluated through immediate settlement analysis, which was carried out employing four most widely used methods. It included analysis of the soil data from cone and dynamic penetration tests, boreholes and laboratory tests. Soil properties were estimated from site investigation and soil exploration program according to Lithuanian standards. Pile settlement analysis showed that settlement value was 14 mm (pile toe settlement), and settlement value of elastic deformation of pile from vertical compressive loads was 3 mm. For such structure, foundation settlement should not be more than 16 mm (i.e., no more than 2 % of pile diameter). It was estimated that for pile of diameter 800 mm, pile length of 24 m was sufficient to endure overall loads

New European Union method for the design of reinforced concrete structures exposed to fire temperatures

The analysis of a method for the design of reinforced concrete structures exposed to fire temperatures is presented in the article. The main essential factors which must be evaluated in the design of structures and their parts to provide their adequate carrying capacity and ability to prevent fire spread are analyzed. In fire design it is necessary to take into account the behaviour of structural system exposed to fire temperatures, the possible effect of heat and positive effects of active and passive protection systems against fire and the consequences of collapse of the structure. The method is intended for buildings, fire load is associated with the building and its use. At the same time thermal and mechanical actions for structures exposed to fire are considered. Article in Lithuanian. Nauja Europos sąjungos gaisro temperatūrų veikiamų gelžbetoninių konstrukcijų projektavimo metodika Santrauka. Straipsnyje pateikta naujos gaisro temperatūrų veikiamu gelžbetoninių konstrukcijų projektavimo metodikos analizė. Išanalizuoti pagrindiniai esminiai veiksniai, kuriuos privalu įvertinti projektuojant konstrukcijas ir jų dalis taip, kad jos būtu pakankamos laikomosios galios ir reikiamai ribotų gaisro plitimą. Rengiant gaisrinius projektus, reikia įvertinti konstrukcinės sistemos elgseną veikiant gaisro temperatūroms, galimą šilumos poveikį ir teigiamus aktyviųjų ir pasyviųjų apsaugos prieš gaisrą sistemų efektus kartu su šių trijų savybių neapibrėžtumais ir konstrukcijos griuvimo pasekmėmis. Metodika skirta pastatams, gaisro apkrovą siejant su pastatu ir jo naudojimu. Kartu nagrinėjami gaisro veikiamų konstrukcijų šiluminiai ir mechaniniai poveikiai. Reikšminiai žodžiai: gaisro temperatūros, konstrukcijų projektavimas, šiluminiai ir mechaniniai poveikiai. First Published Online: 21 Oct 201

Effect of long‐term loading and fire temperatures on mechanical properties of concrete

During a fire, reinforced concrete structures are exposed to high temperatures and subjected to long‐term action of variable and permanent loads. This paper deals with analysis of influence of fire temperatures and long‐term action of loads on compression strength and deformability of normal weight concrete. Results of experimental investigations of compression strength and deformability of normal‐weight concrete subjected to long‐term load and exposed to high temperature are presented. Specimens in the shape of prisms of normal‐weight concrete were subjected to long‐term compression of intensity η(t) = σc/fc (τ) = 0,3. The long‐term compression was sustained for 400 days. Some of the specimens were heated (at 250 °C and 450 °C) before application of long‐term load; other specimens were heated after application of long‐term load. The paper presents coefficient of service conditions for concrete subjected to long‐term load and exposed to high temperature that gives opportunity to evaluate compression strength and deformation properties of concrete. Ilgalaikės apkrovos ir gaisro temperatūrų įtaka betono mechaninėms savybėms Santrauka Nagrinėjamas gaisro temperatūrų ir ilgalaikės apkrovos poveikis sunkiojo betono gniuždomajam stipriui ir deformacinėms savybėms. Pateikiami ilgalaike apkrova ir aukšta temperatūra paveikto sunkiojo betono stiprumo ir deformacijų tyrimo rezultatai. Sunkiojo betono bandiniai – prizmės, apkrautos ilgalaike gniuždančia apkrova, kurios intensyvumas η = σc/fc = 0,3. Ilgalaikių bandymų trukmė – 400 parų. Dalis bandinių kaitinti (temperatūra 250 °C ir 450 °C), prieš juos apkraunant ilgalaike apkrova, kiti bandiniai kaitinti po to, kai buvo apkrauti šia apkrova. Pateikiami ilgalaike apkrova ir aukšta temperatūra paveikto betono patikimumo koeficientai, leidžiantys įvertinti betono gniuždomąjį stiprį ir deformacines savybes. Reikšminiai žodžiai: betonas, ilgalaikė apkrova, gaisro temperatūros, gniuždomasis stipris, deformacijos. First Published Online: 14 Oct 201

Quality Problems of Lithuanian Civil Engineering Design Documentation

General situation in civil engineering design documentation is reviewed in this paper. Some characteristic mistakes in design are presented. Authors using their experience in engineering examination of real structural designs, discuss statistical data of the latest years. An attempt to improve engineering solutions using analysis of inaccuracies in design documentation and suggestion of new methods for its developmement, instead of creation of new theories and methods of structural analysis, is made. Such an approach in engineering is less popular as time and resourses for its implementation are required. Nevertheless, this method of solution for the problem of technical product quality and qualification of specilists is more correct. Finally, conclusions about quality as well as conditions for designers and recommendations for developent of national design codes are made

Using Reinforced Concrete Arches for Long Span Roof Constructions

Aptariamos statybos praktikoje naudojamos didelio tarpatramio denginių laikančiosios konstrukcijos, tokių konstrukcijų projektavimo pagal Euronormas ypatumai. Nagrinėjamas gelžbetoninės dviejų lankstų denginio arkos patikimumas, išskiriami rodikliai, darantys didžiausią įtaką konstrukcijos patikimumui, atliekama konstrukcijos parametrinė analizė. Formuluojamos praktinės išvados.Abstract in English. The article focuses on the use of long span load-bearing roof constructions in building practices as well as their design in accordance with European standards. Moreover, it also offers the analysis of the reliability of the reinforced concrete two-hinged roof arch and singles out the parameters that have the biggest influence on the reliability of the construction. The article analyses the construction parameters and, finally, presents the concluding remarks

Design revisions of complex building structures: work experience in Lithuania, legislative, organizational and technical aspects

This paper presents an engineering survey based on experience of the authors during design and expertise of complex building structures in period of 2000–2014. Legal, organizational and technical aspects in a procedure of changes in structural design documentation are investigated. Separate actions for implementing changes according to legislative documents in Lithuania in technical and working structural projects are presented by a general algorithm. Actual questions about sequence in proceeding with local and global analytical calculations during designing of complex structures and peculiarities of processing revised structural drawings and text documents are described in this paper. Relevance of the subject is illustrated by an example of a successful decision in solving common construction and design problems of an office building in Vilnius. Finally, conclusions and recommendations are given. This paper is an investigation of the considered problem and is designated for science researchers in civil engineering, educational and public organizations working with refinement of the design procedures and project documentation handling, and for practicing engineers

Assessment of different methods for designing bored piles / Skirtingų metodų vertinimas projektuojant gręžtinius pamatus

This work concerns the design of bored piles on the site of Elektrenai Power Plant in Lithuania. Equipment for supporting bored pile foundation in the power plant consists of a gas turbine, a steam turbine and a generator. The foundation not only endures high loads but also sustains a strong dynamic impact due to the vibration of equipment in the power plant under working conditions. A solution to the pilling problem was adopted for the following reasons: i) the insufficient capacity of soil to support acute stresses; ii) high requirements of slab settlements and bearing capacity with regard to the main equipment used in the power plant. The objective of this work is to assess the methods used for estimating immediate settlement and carrying capacity of the pile considering cone penetration tests conducted in Elektrenai power plant. For settlement estimation, four methods, including Bowles (Bowles 1997) and Schmertmann methods (Schmertmann 1978) as well as the methods described in EN 1997-2 and NEN 6743 (NEN 6743:1991/A1:1997) were employed. A carrying capacity of the pile was evaluated with the help of direct methods that utilize data on the cone penetration test (CPT). The following direct methods such as the Schmertmann method (Schmertmann 1978), the de Ruiter and Beringen method (de Ruiter, Beringen 1979), the Bustamante method (LCPC) (Bustamante, Gianeeselli 1982) and the methods described in EN 1997-2 and NEN 6743 (NEN 6743:1991/A1:1997) were applied. Pilling foundation was evaluated performing immediate settlement analysis and included the examination of soil data received from cone and dynamic penetration tests, boreholes and laboratory tests. Soil properties were estimated taking into account investigation into the site of Elektrenai power plant and a soil exploration program developed according to Lithuanian standards. Pile settlement analysis showed that settlement value made 13.6 mm (pile toe settlement) and the settlement value of an elastic deformation of the pile from vertical compressive loads was 2.3 mm, for the most conservative situation. For such structure, foundation settlement should not exceed 16 mm. Elektrenai power plant has high reliability requirements, and therefore the pile having the diameter of 800 mm with a pile length of 27 m was adopted to endure overall loads. Santrauka Straipsnyje nagrinėjami įvairūs skaičiavimo metodai, skirti gręžtiniams pamatams projektuoti. Lietuvos elektrinės teritorijoje projektuojant kombinuoto ciklo dujų turbinos bloko pamatus, dėl ypatingų statinio reikalavimų polių nuosėdžiams bei laikomajai gebai buvo parinkti gręžtiniai poliai. Pagrindinis darbo tikslas – įvertinti gręžtinių polių nuosėdžių ir laikomosios gebos skačiavimus pagal statinio zondavimo duomenis bei analitinius sprendimus, taikant skirtingus skaičiavimo metodus. Polio nuosėdžiams ir laikomajai gebai vertinti buvo taikyti šie metodai bei standartai: Bowles, Schmertmann, de Ruiter ir Beringen, Bustamante (LCPC), EN 1997-2 ir NEN 6743 standartų metodika. Remiantis statinio ir dinaminio zondavimo bei laboratorinių tyrinių duomenimis, suminio nuosėdžio reikšmė buvo gauta lygi 16 mm, iš jų 2 mm sudaro nuo vertikaliosios apkrovos gniuždomo polio deformacija. Tokio tipo statinių pagrindo nuosėdis negali būti didesnis nei 2 % polio skersmens. Atlikti skaičiavimai parodė, kad 800 mm skersmens ir 27 m ilgio polio visiškai pakanka statinėms ir dinaminėms apkrovoms atlaikyti. Reikšminiai žodžiai: statinis zondavimas, gręžtinių polių laikomoji galia, polių nuosėdžių skaičiavimai, dujų turbinos, gilieji pamata