This thesis presents a state-of-the-art review on the 3D printing technology and its

applications in construction. This technology is the computer aided design and manufacturing of

objects. It is a new way of manufacturing products by layer to layer adhesion. The material can

include thermoplastics, photopolymers, concrete and many other materials. The major benefit of

3D printing applications in construction is the ability to 3D print concrete without the use of

formwork. The use of concrete 3D printing allows for the construction of concrete structures that

are cost and time efficient. Construction of concrete 3D printing deviates from typical methods of

concrete construction and therefore requires structural analysis and novel engineering design to

maintain structural integrity. A review of concrete 3D printed structures that are currently being

printed and how 3D printing works are presented in this thesis to allow for informed design

decisions when 3D print structures. The overview of the 3D printing will also include the

feasibility of 3D printing structures on planet Mars. Due to the autonomous nature of 3D printed

construction, structure can be constructed on the desolate planet before astronauts arrive to Mars.

The use of 3D printing has a variety of applications and can increase the efficiency of structural

engineering design and construction.

This study focuses on structural optimization of the orthotropic sandwich cementitious composite systems. In order to develop a sandwich panel with high structural performance, design optimization techniques must be utilized to achieve full composite action as well as light weight, and high thermal insulation. This study involves both linear and nonlinear finite element analyses and parametric optimization. The verification and calibration of the numerical models will be based on the experimental results of numerous full-scale tests that were performed on two types of commercially produced sandwich panels under different loading scenarios at University of California Irvine.

In order to minimize the number of design variables required for producing an optimum sandwich panel, the Taguchi statistical method for quality control is utilized. In this method, statistically planned experiments (or numerical simulation runs) are used to identify the settings of the sandwich panel design parameters that result in optimum design.

Additionally, the Genetic Algorithm (GA) is used as an alternative approach for optimization, in order to evaluate the optimum design and build further confidence in our optimum design. GA combines Darwin's principle of survival of the fittest and a structured information exchange using randomized crossover operators to evolve an optimum design for the cementitious sandwich panel.

Among the different initial parameters to be evaluated in the study are: (i) shear connectors’ geometry, volume fraction, and distribution; (ii) The thickness of exterior cementitious face sheets; (iii) The size and geometry of the exterior face sheets steel reinforcement details.

Ultimately, the proposed optimization method reduced the Cost of Material of CSP by the by almost 48% using GA. In the same time, alternative design for CSP have been proposed where the optimization process increased the Thermal Resistance of the CSP by 40% compare to the conventional models currently available in the market while meeting the design Criteria’s based on the ACI Code. Pareto-optimal front and Pareto-optimal solutions have been identified. Correlation between the design variables of CSP is verified and design recommendation have been proposed for CSP manufacturers and structural designers.

The present study focuses on the evaluation of the static and dynamic behavior of cementitious sandwich panels with parallel steel wire shear connectors. The study is divided into two parts: (i) large-scale experimental evaluation of different structural sandwich members subjected to different types of loading regimes, and (ii) analytical procedures to predict the behavior of such panels. However, and due to the lack of experimental data on the behavior of such sandwich panels, the emphasis of this study is on full-scale experimental evaluation. In the analytical part of the study, modified procedures, based on the experimental observations, following the general guidelines of the American Concrete Institute (ACI 318-11) were adopted. Also, the experimental program focused on assessing the out-of-plane flexural behavior of floor/roof sandwich slabs. Both simply supported and two-span continuous large-scale floor/roof slabs, with different boundary conditions and details, were evaluated. The experimental results were compared to the analytical predictions and well agreement between the results was achieved. The study also included several large-scale element experiments that were conducted on walls subjected to axial, shear, eccentric and flexural loadings conditions as well as exterior and interior corner connections. These tests are considered to be a pioneering research work that are not available to-date in published literature. A summary of the test setup, test procedures and experimental results that included quasi-static and cyclic load-displacement (P-δ) and Stress- Strain (σ−ε) curves are presented and discussed herein.

The comprehensive experimental program provided much needed information to the structural engineers that lack the knowledge on the service and ultimate performance of this type of sandwich structural elements. For example, the experimental results provided important information on the suitability of the sandwich panels with parallel wire connectors for the use as floors and roof slabs. In addition, the experimental results identified the different failure modes that are not similar to those for solid concrete elements.

The simplified analytical procedures that followed, in general, the requirements of ACI 318-11 with justifiable modifications succeeded to provide conservative estimates to the capacity of each structural sandwich element evaluated in this study. Numerical design examples for typical residential buildings that were performed using the proposed analytical procedures are also presented.

Conclusions drawn from this pioneering study is summarized and recommendations for future research work is presented in this thesis.

ABSTRACT OF THE THESIS

Experimental Evaluation of Two-Way Sandwich

Paneled Slabs

By

Surbhi Dadlani

Master of Science in Civil Engineering

University of California, Irvine, 2015

Professor Dr. Ayman S. Mosallam, Chair

This research focuses on the experimental evaluation of the flexural behavior of light-weight two-way slabs made of three-dimensional (3D) sandwich panels subjected to out-of-plane loading. The sandwich panels evaluated in this study were composed of two exterior faces made of high-strength mortar reinforced with bidirectional cold-rolled steel wires. The sandwiched core consists of fire retardant Expanded PolyStyrene (EPS) foam core. In this study, three square large-scale sandwich slab specimens with different dimensions and spans were subjected to mid-span loads up to failure. All specimens were instrumented with electrical strain gages and string potentiometers to monitor steel and mortar strain variations and deflections. During each experiment, loads, strains, and vertical deflections were monitored and the results were analyzed. Load-deflection (P/) and stress-strain () curves were also developed for each specimen at different locations. Cracks initiation and propagation were monitored throughout each test and crack mapping was performed for each slab specimen. Peak load, ultimate strain, and maximum vertical displacement were observed and the failure load for each specimen was identified and recorded. A simplified analytical procedure that followed the requirements of ACI 318-14 was developed to provide conservative estimates of the capacity of each structural sandwich slab evaluated in this study. Experimental results were compared with the predicted capacity and deflection of each sandwich slab specimen and a good agreement was achieved in the linear range.

Aims

Methods

Results

Conclusion

With millions of poor and homeless people in the world and the presence of extensive bamboo resources in many regions, a part of the affordable housing problem can be solved by providing structural design for bamboo houses. In this study, structural evaluation of a bamboo arch was performed. In addition, a numerical finite element model using ANSYS software was developed to simulate the behavior of the bamboo structure. The study included a literature review of relevant published technical papers, books and reports. Experimental tests were conducted on the full-scale bamboo structure to verify the scissor action of joints to transfer load and to study the short-term creep behavior for controlling the deflection limits to satisfy the building standards as per CBC 2013. The finite element model was used to understand the expected behavior of the bamboo arch structure under gravity loading. The finite element model results were used to determine the possible improvement to stiffen the structural joints by using steel cables. This study is just a step towards providing an alternative for feasible housing design using bamboo as a structural material.