Procter & Gamble (United Kingdom)
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Experimental and numerical investigation of the seismic response of confined masonry walls
Get PDFConfined masonry (CM) is one of the most popular and affordable earthquake-resistant con-struction technology for masonry structures. The reinforced concrete (RC) tie-columns in such construction play a crucial role in improving seismic response. However, their interaction with the masonry warrants a review due to recent changes in masonry construction, which are typical for Southeastern Europe. The modern masonry walls built from clay units are thick to achieve thermal efficiency. The tie-columns size has also increased, but they are narrower than the masonry. A part of masonry thus protrudes from the area confined by tie columns, which can lead to stress concentrations and early onset of damage of the protruding masonry, as was observed in recent tests on such masonry. This paper numerically analyzes this problem using a detailed three-dimensional (3D) finite element (FE) model that can capture this effect. The numerical model was developed in ABAQUS, and uses Concrete Damage Plasticity (CDP) material model to model the brittle response of clay blocks. All input data for the numerical model were obtained by dedicated tests. The results are compared to tests of walls in terms of damage propagation, strength and deformation response and show that damage to the protruding masonry can be successfully modelled. The results show a good alignment with the experiments and can be used for detailed modelling of seismic response of CM masonry structures and further research
Temporal distribution of causes of delay as a new approach to discovering the root causes of delay
No full textGrađevinski projekti su jedinstveni, dinamični i složeni. Karakteriše ih multidisciplinarno okruženje i veliki broj učesnika koji proizvode značajan obim podataka. Ovo su samo neki od razloga zašto građevinski projekti ne uspevaju da ostvare planirano trajanje. Otkrivanje baznih uzroka kašnjenja je prvi i najvažniji korak ka eliminisanju ili umanjenju potencijalnih kašnjenja na budućim projektima. Postojeći pristupi se baziraju na ekspertskom mišljenju uz rangiranje uzroka kašnjenja prema parametrima kao što su verovatnoća pojave i mera uticaja na trajanje projekta. Ovakav pristup agregira subjektivizam i pristrasnost eksperata i shodno tome ne doprinosi otkrivanju baznih uzroka kašnjenja. Kroz ovo istraživanje se predlaže inovativni pristup otkrivanju baznih uzroka kašnjenja – analiza vremenske distribucije uzroka kašnjenja kao jedinstvena karakteristika DREAM-a (Delay Root-cuases of delay Extraction and Analysis Model). Analizom informativnih grafikona vremenske distribucije eksperti mogu da razumeju prirodu kašnjenja kroz sve faze projekta i otkriju bazne uzroke kašnjenja. Na taj način se omogućava podrška donosiocima odluka na budućim projektima u cilju proaktivnog upravljanja rizicim
Planning, control and change management in a single software APP
No full textGrađevinski projekti ne ispunjavaju ciljeve i opterećeni su problemima u realizaciji. Upravljanje projektima može se unaprediti razvojem objedinjujućih aplikacija. Najbolje putem sinergije nauke i prakse, koristeći fondove za finansiranje inovacija koji multidisciplinarnim pristupom osiguravaju usklađenost naučnih ideja sa potrebama tržišta. U radu je prikazan razvoj jedinstvene aplikacije za planiranje, kontrolu i upravljanje promenama za projekte izgradnje poslovno-stambenih objekata iz ugla investitora, uz pomoć dva programa Inovacionog fonda RS. Problem u praksi je komplikovano upravljanje promenama izazvano informatičkom nepovezanošću planiranja, normiranja i finansijskih proračuna. Predloženo rešenje je objedinjujuća aplikacija za upravljanje mesečnim promenama realizacije, dinamike i priliva/odliva, bazirana na „finansijski kvantifikovanom gantogramu“ sa kumulativnim cashflow-om kao kontrolnom merom. Program Dokaz koncepta omogućio je razvoj demo verzije aplikacije. Kao obavezan deo programa, istraživanje tržišta je ukazalo na neophodnost kreiranja posebnog modula za planiranje sa mogućnošću automatskog kreiranja inicijalnog dinamičkog plana u formi „finansijski kvantifikovanog gantograma“. Nastavak razvoja je sproveden kroz program Transfer tehnologije. Modul za planiranje omogućava sagledavanje gabarita objekta, dinamike, troškova i rizika, koristeći samo podatke iz Informacije o lokaciji. Za automatsko kreiranje inicijalnog dinamičkog plana osmišljen je „univerzalni ritmični ciklogram“ na nivou glavnih tokova koji je određen trajanjem prvog toka i vremenskim zazorim
Key performance indicators for construction equipment
No full textThe key performance indicators (KPI) are financial and non-financial
measures (metrics) used at different levels in an organisation to assess success in
achieving defined goals, critical success factors, strategies and plans, respectively,
as the level of meeting the expectations of different business participants. For a
construction company to successfully manage the work of machinery, it is of great
importance to choose key performance indicators. The paper presents a proposal
of indicators that need to be measured, the method of their measurement as well
as the expected values
Site frontier - software for process optimization during steel structure erection works
No full textEfficient data management during the construction of large-scale steel structures such as
industrial facilities is crucial due to the extensive amount of data and the numerous
element state changes during the erection process. Swift and accurate data management
is necessary for making important decisions on time. The traditional assemblies tracking
approach based on technical drawings carries a higher risk of errors due to human
factors. The software system Site Frontier successfully addresses these challenges by
employing an advanced mathematical model that considers the interdependencies of
structure elements, as well as the conditions and constraints at the construction site. By
utilizing the Site Frontier software, significant savings can be achieved in material costs,
labor hours, and the resources of engineers and equipment
Flat slab response for seismic and cyclic actions prediction with numerical models
No full textAs an outcome of a recent European research project, the modelling of the response of flat slab structures for seismic and cyclic loading was the object of a blind competition. No other blind tests are available in the literature on this topic. The test results concern a full-scale, two-storey, three-by two bay reinforced concrete flat slab frame. The seismic tests were carried out using a hybrid pseudo-dynamic test up to the ULS design excitation. The cyclic test reached a drift capacity of 2.5% and 6% in two concatenated tests. A synthesis of the models of three participants is provided, with one 3D NLFE (Nonlinear finite element) models and two slab and frame models. The CSCT (Critical Shear Crack Theory) model included in the fib MC2010 was adopted in the two latter to predict punching failure. The results are presented and discussed. Conclusions are drawn on research developments and practical approaches
Experimental determination of R curves for European spruce using DCB tests
No full textThis paper presents an experimental procedure for obtaining the fracture resistance (R curve) of solid wood specimens made of spruce. Double Cantilever Beam (DCB) tests were performed in order to determine energy release rate vs crack length in Mode I wood fracture (crack opening). Ten wood specimens were loaded using the Universal Testing Machine and force-displacement curves were recorded. The most important parameter - crack length was monitored as the crack propagates using Digital Image Correlation (DIC) method. In order to obtain accurate R curve results, procedure which includes calculating cumulative released energy was employed. The cohesive energy Gf was determined based on the R curves. These results can further be analysed in order to obtain cohesive law for Mode I fracture of wood
Influence of slab deflection on the out-of-plane capacity of unreinforced masonry partition walls
No full textSevere damage of non-structural elements is noticed in previous earthquakes, causing high economic losses and posing a life threat for the people. Masonry partition walls are one of the most commonly used non-structural elements. Therefore, their behaviour under earthquake loading in out-of-plane (OOP) direction is investigated by several researches in the past years. However, none of the existing experimental campaigns or analytical approaches consider the influence of prior slab deflection on OOP response of partition walls. Moreover, none of the existing construction techniques for the connection of partition walls with surrounding reinforced concrete (RC) is investigated for the combined slab deflection and OOP loading. However, the inevitable time-dependent behaviour of RC slabs leads to high values of final slab deflections which can further influence boundary conditions of partition walls. Therefore, a comprehensive study on the influence of slab deflection on the OOP capacity of masonry partitions is conducted. In the first step, experimental tests are carried out. Results of experimental tests are further used for the calibration of the numerical model employed for a parametric study. Based on the results, behaviour under combined loading for different construction techniques is explained. The results show that slab deflection leads either to severe damage or to a high reduction of OOP capacity. Existing practical solutions do not account for these effects. In this contribution, recommendations to overcome the problems of combined slab deflection and OOP loading on masonry partition walls are given. Possible interaction of in-plane (IP) loading, with the combined slab deflection and OOP loading on partition walls, is not investigated in this study
Application of Hardening State Parameter Constitutive Model for Prediction of Overconsolidated Soft Clay Behavior Due to Embankment Loading
Get PDFThis paper investigates the possibility of the application of the HArdening State Parameter (HASP) constitutive model for numerical modelling of overconsolidated soft clay under embankment loading. The HASP constitutive model is a critical state soil model with a combined hardening rule that uses a state parameter to determine the dilatancy of overconsolidated clay. The model overcomes some shortcomings of the Modified Cam Clay (MCC) model in the prediction of overconsolidated clay’s behavior, while preserving the simplicity and the same set of five parameters. The HASP model was implemented in finite element software. In order to verify the applicability of the model in predicting the behavior of soft overconsolidated clay due to embankment loading, two examples reported in the literature are analyzed. The numerical predictions of the HASP model are compared with the field measurements of ground settlements and pore water pressures, and with the MCC model’s predictions. The results indicate that the HASP model predicts the development of the settlements of the overconsolidated soft clay deposits with a high accuracy from an engineering point of view. There are certain deviations from the field measurements in predicting the pore pressure development, which is often observed for other models as well. For the embankment settlement assessment, as important serviceability issue, the HASP model has an advantage over more complex models that require a large number of parameters. Since the parameters of the HASP model are obtained from standard laboratory tests, it can be easily applied for routine geotechnical analyses
Stability analysis of FGM plates by using layer wise displacement model
Get PDFIn this paper, the stability analysis of simply supported functionally graded material (FGM) plate under mechanical in–plane compressive loads is analyzed. The displacement model based on Generalized Laminate Plate Theory (GLPT) assumes piece–wise linear variation of in–plane displacements, constant transverse displacement, non–linear strain–displacement relations (in von Karman sense) and linear material properties. The properties of FGMs are assumed to be constant in xy–plane and vary through thickness by a power law function in terms of volume fraction of the constituents. The mathematical model includes the quadratic variation of transverse shear stresses within each layer of the plate. The principle of virtual displacements (PVD) is used to derive Euler–Lagrange differential equations of linearized buckling problem. Closed form solution is derived following the Navier’s technique and solving the eigenvalue problem. The original MATLAB computer program is coded for the numerical solution. The results reveal that the effects of side–to–thickness ratio, power–low index and modulus ratio have significant effect on critical buckling loads of FGM plates