STR-930: CROSS LAMINATED TIMBER WALLS WITH OPENINGS: IN-PLANE STIFFNESS PREDICTION AND SENSITIVITY ANALYSIS

Cross-laminated timber (CLT) is gaining popularity in residential and non-residential applications in the North American construction market. An accurate quantification of in-plane stiffness of the CLT walls with openings is required to design a CLT structure subjected to lateral loads. Nevertheless, till today, no general approach is available for the design of CLT-members loaded in plane and there are no standardized methods for determining the stiffness of CLT shearwalls in the respective material design standards: the CSA O86 in Canada, and the NDS in the US. This study aims to quantify the stiffness of CLT walls with openings under in-plane loading. A finite element (FE) model of CLT walls was developed modelling wood as orthotropic elastic material and the glue-lines between layers using non-linear contact elements. The FE model was verified from test results of CLT panels under in-plane loading. A parametric study was performed to evaluate the change in stiffness of CLT walls with the variation of opening size and shape. A simplified equation to predict the in-plane stiffness of CLT walls with openings was proposed. Subsequently, a sensitivity analysis was performed using Meta-model of Optimal Prognosis (MOP) to evaluate the contribution of each parameter on the model response

Примена на геофизичките методи во рударството

Со помош на геофизичките истражувања се постигнува брзо, ефикасно, економично и недеструктивно решавање на одредени проблеми од областа на геологијата, рударството, градежништвото, водостопанството, археологијата, екологијата и др. Геофизичките техники традиционално се поврзуваат со истражување на металични наоѓалишта, но тие исто така, нудат потенцијал за евалуација на геотехничките параметри поврзани со наоѓалиштата на минерали при проектирањето на рудникот. Ваквите геотехнички параметри оценуваат не само квалитетот и димензиите на наоѓалиштето, туку и да го карактеризираат квалитетот на карпестата маса, геолошката структура и режимот на подземните води. Улогата на геофизиката во истражувањето на минералите брзо се прошири во последните децении, но нејзината важност во рударството сеуште не е доволно применета. Бариерите за поголемо прифаќање на геофизиката во рударството се повеќе „културни“ отколку технички, бидејќи рударските компании историски (иако несвесно) ефективно ги отстранувале геофизичарите од персоналот за развој и производство на рудниците

Geomechanical characteristics of the tailing dam "Topolnica"

The tailing dam "Topolnica“ is a storage type because it has a dual purpose, that is used for the disposal of tailings flotation in the space of a river bed and it accumulate fluid flow water from the river Topolnica which serving open pit mine with drinking water. First projected elevation was 610 m above sea level, it has long been exceeded and reached final height of 90 meters. In the last couple of years, when the elevation of the tailing dam arid approached to the final projected elevation, the open pit mine approached to develop technical documentation for the same elevation. It was made a additional project for elevation to the upstream slope for 20 meters, elevation 630 m. In 2006 it was made second additional project for elevation of the upstream slope for another 24 meters, elevation 654 m and a total height of the crown of 136 meters. With the implementation of a additional project for tailing dam it is numbered as a highest dams in Europe

Seismic performance of braced timber frames

Braced timber frames are efficient lateral load resistance systems in buildings where large open spaces are required, and the more commonly used timber shear wall systems cannot be utilized. Braced timber frames allow for flexibility in the design and use the wood in its strongest direction - parallel to grain in tension or compression. For application in high-risk earthquake zones, however, the ductility of the system is a concern, since energy absorption is typically limited to the connection region. This study focused on seismic behaviour of braced timber frames with particular emphasis on investigating the influence of different connection details on the overall stiffness, strength and seismic energy absorption capacity of the frame. Monotonic tension and cyclic quasi-static tests were conducted on a variety of connections typically used in braced timber frames, utilizing different diameter bolts and high strength glulam rivets with steel side plates. Shake table tests were subsequently conducted on a selected number of single storey braced frames with some of the connections previously tested and on a two storey braced timber frame model with riveted connections. The experimental results from quasi-static tests and shake table tests were used to establish and verify non-linear analytical models representing the load-deformation behaviour of different connections. These hysteresis curves were then introduced in analytical braced frame models. These models were used in a number of non-linear static and dynamic analyses to determine the response of braced frames to the input of five different records from previous earthquakes. From these analyses it was possible to determine the influence of different connection details on the seismic response of the selected types of braced timber frames. Based on the results from the analytical part of the study, an estimate was made on the appropriate force modification factors (R-factors) for earthquake resistant design of braced timber frames, as used in the National Building Code of Canada. Finally, some design and construction recommendations are discussed to inform the reader of the details required to obtain an adequate seismic performance. Possible ways of improving the seismic behaviour of braced timber frames are presented as well.Applied Science, Faculty ofCivil Engineering, Department ofGraduat

Blind prediction of the seismic response of the NEESWood Capstone Building

The NEESWood Project is a multi-year US research project that involves analysis, testing, and societal risk assessment with the intent of safely increasing the height of light-frame wood buildings to six stories in regions of moderate to high seismicity. Within this project a full-scale seven-storey, 12.1 m x 18.1 m, condominium building (one storey steel frame and 6 storey wood frame construction) has been tested during July 2009 on the world’s largest earthquake shake table in Miki, Hyogo, Japan. As part of the NEESWood Project the international engineering community was invited to blind predict the inelastic seismic response of the Capstone Building. In this paper results of the blind prediction using the commercially available DRAIN 3-D structural analysis program are presented. The model for the test structure was composed of essentially rigid straight members connected to semi-rigid rotational springs in the vertical plane to represent the shear walls, while floor and roof diaphragms were assumed as rigid. The semi-rigid spring elements were incorporated into the DRAIN- 3D program using a proprietary subroutine simulating the hysteretic behaviour of wood mechanical connections. Properties of the hold-down rods were also included in the model. The required hysteretic parameters for each spring element were obtained by the data package provided by NEESWood researchers for this benchmark study. The results were then compared in terms of time-history responses, maximum base shear, maximum average displacements, interstorey drifts and hold-down tension forces experienced at each storey

Assessment of seismic design parameters for midply wood shear wall system

A midply shear wall provides greater lateral load capacity per unit length than a standard shear wall. The improved performance is achieved by placing the sheathing between wall stud members, which subjects the nails to double-shear when the wall is loaded in shear. Tests have shown that the average lateral load capacities and energy dissipations of midply walls can be more than three times that of standard shear walls, while their stiffness can be between two to three times the average stiffness of standard shear walls. A proposal for implementation of the midply wall system in wood design codes in North America is presented. Non-linear dynamic analyses of a four-storey wood-frame building were used to determine the seismic design parameters for midply shear walls. The analysis utilized a suite of 22 selected earthquake records scaled to the peak ground acceleration stipulated in the National Building Code of Canada 2005 for Vancouver, British Columbia. The probability of failure was determined for building built with both standard and midply shear walls. Using the standard shear walls as the bench mark, this study indicates that a ductility-related force modification factor R d = 3 could be safely assigned for the midply shear wall system to achieve the same safety level as the standard shear wall system

Геометалургија

Повисоките еколошки и социо-економски барања во експлоатацијата на идните минерални ресурси бараат сеопфатно знаење за рудните телата дури и во раните фази на рударскиот процес. Геометаллургијата комбинира геолошки и минерални информации за да создаде просторен модел за планирање и управување со производството. Примената на геометаллуршкиот концепт ја подобрува ефикасноста на ресурсите, ги намалува оперативните ризици и помага во оптимизирање на производството на таков начин што исто така се разгледуваат одржливоста и социо-економските фактори. Со геометаллуршки модел е можно да се изучува различно производствено сценарио почнувајќи од истражување до изводливоста и фази на производство. Постојат некои алтернативни начини за градење на геометаллуршки модел, но минералошкиот пристап е генерички (заеднички) и може да се усвои за секаков вид на минерални суровини. Овој документ опишува како еден ваков концепт се користи во рударската индустрија и ги демонстрира придобивките во однос на подобрената ефикасност на ресурсите во различни рудни депозити. Клучни зборови