EVALUATION OF WAYS TO RECOVER LATE CONSTRUCTION PROJECTS

Delay in construction projects is a common issue. Considerable percentages of projects fall behind schedule causing damages to almost all involved parties. Owners may experience losses due to postponed completion dates and Contractors may face liquidated damages. Even Architects and Engineers may face additional challenges resulted by delays. In this thesis possible solutions to compensate delays before reaching the estimated end of a project have been studied. Effective usage of the remaining time to completion of the project has been the main concern, and advantages and disadvantages of each solution are studied

BEHAVIOR OF FIBER REINFORCED POLYMER COMPOSITE PILES WITH ELLIPTICAL CROSS SECTIONS IN INTEGRAL ABUTMENT BRIDGE FOUNDATIONS

Every year in the US and other cold-climate countries considerable amount of money is spent to restore structural damages in conventional bridges resulting from (or “caused by”) salt corrosion in bridge expansion joints. Frequent usage of deicing salt in conventional bridges with expansion joints results in corrosion and other damages to the expansion joints, steel girders, stiffeners, concrete rebar, and any structural steel members in the abutments. The best way to prevent these damages is to eliminate the expansion joints at the abutment and elsewhere and make the entire bridge abutment and deck a continuous monolithic structural system. This type of bridge is called Integral Abutment Bridge which is now widely used in the US and other cold-climate countries. In order to provide lateral flexibility, the entire abutment is constructed on piles. Piles used in integral abutments should have enough capacity in the perpendicular direction to support the vertical forces. In addition, piles should be able to withstand corrosive environments near the surface of the ground and maintain their performance during the lifespan of the bridge. Fiber Reinforced Polymer (FRP) piles are a new type of pile that can not only accommodate large displacements, but can also resist corrosion significantly better than traditional steel or concrete piles. The use of FRP piles extends the life of the pile which in turn extends the life of the bridge. This dissertation studies FRP piles with elliptical shapes. The elliptical shapes can simultaneously provide flexibility and stiffness in two perpendicular axes. The elliptical shapes can be made using the filament winding method which is a less expensive method of manufacturing compared to the pultrusion or other manufacturing methods. In this dissertation a new way is introduced to construct the desired elliptical shapes with the filament winding method. Pile specifications such as dimensions, number of layers, fiber orientation angles, material, and soil stiffness are defined as parameters and the effects of each parameter on the pile stresses and pile failure have been studied. The ANSYS software has been used to model the composite materials. More than 14,000 nonlinear finite element pile models have been created, each slightly different from the others. The outputs of analyses have been used to draw curves. Optimum values of the parameters have been defined using generated curves. The best approaches to find optimum shape, angle of fibers and types of composite material have been discussed

Footprint of construction errors on the structural damages

The majority of structural failures are attributable to errors in construction. This problem exists in all countries, but it is more frequent in developing communities. This study focuses on construction errors of structures in Tehran, the capital city of Iran. In this study, eighty-eight buildings have been investigated during the construction phase. These buildings have been categorized into ten types and have been distributed in twenty-two suburbs. Results showed that the buildings of Tehran can suffer from at least forty-nine major construction problems. In addition, for the first time, this research has introduced the following three terms in relation to prioritizing of construction errors: Relative Importance Factor (RIF), Priority Index (PI) and Structural Importance Index (SII). As a part of the conclusions, the results showed one hundred percent of investigated buildings are affected dramatically by the “use of untrained workers” and “lack of sampling or wrong sampling” too. In this regard, the RIF and PI of each “Lack of sampling or wrong sampling” and “use of untrained workers” are 100 and 1, respectively. Also, suburb 3 has the best construction conditions while suburb 10 has the worst

An experimental study on the lateral pressure in foam-filled wall panels with pneumatic formwork

Applications of structural wall panels using flexible formwork systems have recently attracted the attention of architects and engineers. Many of such panelised systems in the market are foam-filled walls, mainly presented in the form of sandwich panels. Knowledge of cast-in-situ induced lateral pressure on the formwork is critical for the economical and safe design of flexible formwork for construction. Formwork cost, on the other hand, comprises a high proportion of the total cost of a building constructed by cast-in-situ materials. Although extensive research has been conducted on the lateral pressure of concrete formwork, the components and mechanics of the lateral pressure in foam-filled walls have not been thoroughly understood. This paper will investigate the lateral deformation, and then lateral pressure on flexible fabric formwork used for construction of polyurethane foam-filled panels. From the lateral pressure on the formwork, the tension forces in the ties are calculated by measuring the compressive force developed between the formwork edges. The results are used for design of intermediate ties for controlling the lateral deformations in an innovative foam filled panelised system, which has been designed for rapid assembly of semi-permanent buildings for post disaster housing. Keywords: Flexible formwork, Lateral deformation, Pressure, Polyurethane foam, Fabric formwor

A creative rapid assembly modular free form pavement for post-disaster temporary roads and sidewalks

Tahmoorian, F ORCiD: 0000-0002-5158-2077Immediate aid to survivors of a natural disaster is the keynote to crisis management. Providing temporary access is one of the most important principles of immediate relief. However, in the postdisaster conditions, it is not possible to use road construction machinery, especially in rural areas. Therefore, in this study, the feasibility of using a Rapid Assembly Building (RAB) system for the temporary pavement with the possibility of rapid construction, which follows the natural topography of the place, is investigated. The introduced system consists of a high-density polyurethane (PUR) foam core as well as two continuous layers of high-density polyethylene (HDPE) facings. For this purpose, the mechanical properties of the materials and composite pavement were determined by a series of laboratory tests. Then, the mechanical performance and bearing behaviour of an element of the presented pavement system was numerically modelled under AASHTO loading. Since in the post-disaster situation, it is not possible to establish the subgrade, an un-compacted subgrade is used for modelling. The results show that this system can be used well in post-disaster situations to provide a rapid, safe, yet robust road without any permanent deformation

A creative validation method for Self Compacting Concrete (SCC) lateral pressure model using Archimedes' law

There is currently no standard that can be used to design formworks capable of predicting lateral pressure applied by Self Compacting Concrete (SCC). Formwork designers have been suggested to design formwork to withstand full hydrostatic lateral pressures unless another rational method based on appropriate and reliable experimental studies is presented. This generally obliges contractors to design very strong formwork systems, with additional and unnecessary costs. On the other hand, approximately all previous studies focused on maximum lateral pressure of SCC and its variation over the formwork height is almost non-existent. In this study, thirty experimental tests were carried out on six series of tubular PVC formworks with the same height of 1500 mm and internal diameters of 70 mm, 100 mm, 120 mm, 130 mm, 170 mm and 240 mm, respectively. In this regard, the total volumetric deformations of formworks are investigated. Simultaneously, the theoretical magnitudes of these deformations are calculated by Finite Element (FE) analysis under the hydrostatic assumption. The results show the total real deformations of formworks have a good agreement with numerical values under hydrostatic pressure assumption when the diameter of formwork increases

Non-reinforced foam filled modules for rapidly assembled post disaster housing

Rapidly assembled structures play an important role in post-disaster housing. This research study introduces a modular non-reinforced foam-filled system for rapidly assembled buildings and studies its structural performance. A novel structural modular construction system using pneumatic formwork is presented and its structural performance as a post-disaster housing system is studied. To that end, this paper presents a numerical analysis using finite element modeling on the foam-filled modular units, together with a set of experimental tests on the elements. Finally, the performance of a real size module made of polyurethane AUW763 against snow and wind loads in critical areas is modeled, using the software ROBOT 2016 and ANSYS. The results demonstrate that the foam-filled modular units successfully meet the standards' requirements for semi-permanent housing even in cyclonic prone areas based on Standards Australia (AS1170.2), International Building Code (IBC-2015) and an American standard as Minimum Design Loads for Buildings and Other Structures (ASCE7-10)

Edgewise and flatwise compressive behaviour of foam-filled sandwich panels with 3-D high density polyethylene skins

In this paper, the edgewise and flatwise compressive behaviour of an innovative sandwich panel, mainly developed for quick assembly of post-disaster housing as well as load bearing panels for pre-fabricated modular construction and semi-permanent buildings, is investigated experimentally and by finite element modelling. The panel is composed of two 3-D high-density polyethylene (HDPE) sheets as the skins, filled with high-density Polyurethane (PU) foam as the core. HDPE sheets manufactured with a studded surface considerably enhance the stress distribution and buckling performance of the sandwich panel. Material characterisation tests and flatwise compression and edgewise compression experiments were performed in accordance with ASTM standards to evaluate the compressive strength and the load-carrying behaviour of the sandwich panels. A finite element analysis and validation were also conducted to model the compressive behaviour of sandwich structures. Results demonstrate that the developed sandwich panel exhibits very good compressive performance