Bartłomiej Sawicki

Technische Universität Braunschweig · Department of Architecture

In Digital Fabrication with Concrete (DFC), reinforcement integration is one of the key challenges to enable large-scale application, and further adoption of DFC by industry. This paper presents an investigation on green state milling as a novel approach to reinforce 3D printed concrete elements, in particular for reinforcement integration during f...

Under service conditions, R-UHPFRC (Reinforced Ultra High Performance Fiber Reinforced Cementitious composite) beams exhibit residual deflection after loading–unloading. This is due to the tensile strain hardening behavior of UHPFRC. The precise calculation of deflection is thus relevant and was not addressed previously. This paper proposes a mater...

The safety of existing bridges may be assessed using data from monitoring. The fatigue damage induced during observation period is extrapolated to the total service duration of a structure, and the reserve capacity is estimated. However, due to the randomness of road traffic, there exists a risk of underestimation of damage using a short-term monit...

Ultra high performance fiber reinforced cementitious composites (UHPFRCs) have demonstrated their outstanding efficiency as structural materials. Determination of the bending resistance of members combining UHPFRC with steel reinforcement bars (R-UHPFRC) using material properties obtained by material testing gives satisfactory results. However, the...

The fatigue behavior of a reinforced UHPFRC (Ultra High Performance Fiber Reinforced Cementitious composite) T-shaped beam under four-point bending is investigated. The beam was subjected to a fatigue loading range equal to 49% of the static resistance and failed after 0.88 million cycles. It was instrumented with extensometers, strain gauges and d...

A combination of multiple nondestructive testing (NDT) methods speeds up the assessment of concrete and increases the precision. This is why the UIR-Scanner was developed at Warsaw University of Technology. The scanner uses an Impact-Echo (IE) method with a unique arrangement of multiple transducers. This paper presents the development of the IE mo...

This paper analyses the influence of monitoring duration on the obtained results using two long term (2.5 years) monitoring campaigns. Two road bridges with different nature of traffic are considered: (a) a heavily loaded two-lane highway viaduct and (b) a state road viaduct with a bi-directional traffic. The deck slabs of both bridges are monitore...

This work investigates the fatigue resistance of reinforced Ultra High Performance Fiber Reinforced Cementitious composite (R-UHPFRC) beams with special consideration of steel rebar – UHPFRC interaction under tensile stresses due to bending. Experimental testing of full-scale beams reveals that the fatigue resistance depends on both minimum and max...

The objective of this thesis is to develop knowledge and methods to prevent fatigue failure of bridges. The Fatigue Limit State is investigated from both the demand (S) and resistance (R) side. The S-part focuses on reduction of uncertainties through monitoring of fatigue action effects: • Analysis of 28-month-long high-frequency monitoring of a sl...

Following the significant improvement in their properties during the last decade, Distributed Fiber Optics sensing (DFOs) techniques are nowadays implemented for industrial use in the context of Structural Health Monitoring (SHM). While these techniques have formed an undeniable asset for the health monitoring of concrete structures, their performa...

This paper presents the results of 28-month-long monitoring of a slab portion of the Chillon viaducts in Switzerland using strain gauges and thermocouples. This post-tensioned reinforced concrete structure was strengthened with a layer of reinforced ultrahigh-performance fibre-reinforced cementitious composite (UHPFRC). The strain gauges are used t...

The Chillon viaducts, in service since 1969, are two parallel structures with a total length of 2.1km each and spans varying from 92 to 104 meters. This post-tensioned precast concrete structure was strengthened with UHPFRC (Ultra High Performance Fiber Reinforced Cementitious composite) in 2014/2015 as, among other aspects, fatigue behavior was of...

Because of its high tensile strength and deformation capacity, UHPFRC (Ultra High Performance Fiber Reinforced Cementitious composite) can theoretically be used without any reinforcement bars or prestressing. However, for more economical design and for reasons of structural robustness, steel rebars should complement the UHPFRC leading to R-UHPFRC (...

The case study of the fatigue safety examination of the 120 years old steel riveted bridge carrying a single railway track on two main girders is presented. The overall assessment according to the Swiss Standard SIA 269 for existing structures indicated sufficient resistance at Ultimate Limit State but not at Fatigue Limit State, and the replacemen...

The demolition of an old structure and replacement with a new one is a very complex, time consuming and expensive task, especially if it needs to be conducted without interruption of its functioning (e.g. carrying traffic). In the case of bridges, closing one of them due to such an action can paralyze the infrastructure net and influence the life o...

The paper presents development of a series of solutions for beams at elevated temperatures which are supposed to serve as benchmark problems for applications of computational models in fire structural engineering. Three cases of loading i.e. pure bending, central force, and uniformly distributed loading, are considered for a simply supported, and f...