Construction and Monitoring of Post-tensioned Masonry Sound Walls


Book Description

The purpose of this project was to document the installation of a post-tensioned concrete masonry sound wall constructed as part of a widening and sound wall project along US 36 near Denver, Colorado. In addition, the wall was instrumented at the time of construction to monitor the loss in prestress in the steel tendons over time due to concrete masonry creep and shrinkage and steel relaxation. Tendon tension was monitored for one year to obtain values for the accumulated losses. Accurate losses in post-tensioned concrete masonry are important for economical design. Currently, there are limited data to support an accurate prediction of prestress loss in concrete masonry.




Behavior of Unbounded Post- tensioned Masonry Walls


Book Description

This book reports on a comprehensive analytical, experimental and numerical study on the flexural response of post-tensioned masonry walls under in-plane loads. It explores an important mechanism in this new generation of structural walls, called “Self-centering”. This mechanism can reduce residual drifts and structural damage during earthquake ground motion, and is particularly favorable for structures which are designed for immediate occupancy performance levels. The book reports on the development and verification of a finite element model of post-tensioned masonry walls. It describes a detailed parametric study to predict the strength of post-tensioned masonry walls. New design methodologies and expressions are developed to predict the flexural strength and force-displacement response of post-tensioned masonry. Experimental study is carried out to better understand the behavior of post-tensioned masonry walls and also to evaluate the accuracy of the proposed design procedure and expressions. The book also includes an introduction to current research on unbounded post-tensioned masonry walls, together with an extensive analysis of previously published test results.




Behavior of Unbonded Post-tensioned Masonry Walls


Book Description

Masonry is one of the most widely used construction materials in the world. Incorporating post-tensioning into masonry offers a simple and cost-effective structural system. The post-tensioning techniques can be applied to different types of masonry members as either bonded or unbonded reinforcement. Recent research has demonstrated that unbonded post-tensioned structural elements including concrete walls, concrete columns, and masonry walls can display high ductility levels while withstanding high levels of seismic loads. When an unbonded post-tensioned masonry wall (PT-MW) is subjected to a lateral in-plane load, a single horizontal crack forms at the wall-foundation interface. The restoring nature of the post-tensioning (PT) force returns the wall to its original vertical position and minimizes the residual displacement. This behavior is specifically favorable for structures which are designed for immediate occupancy performance levels. The rocking mechanism of PT-MWs results in plastic deformation concentrated at the toe of the wall which can be repaired with minimal cost. While in members having bonded PT bars, the force developed in PT bars can be determined considering strain compatibility and equilibrium; for members having unbonded PT bars, theoretical evaluation of the stress developed in PT bars is challenging as it depends on the elongation of the unbonded PT bar. This study aims to get a better understanding of the in-plane behavior of PT-MWs.
















Post-Tensioned Clay Brick Masonry Walls for Modular Housing in Seismic Regions


Book Description

From past research post-tensioned concrete masonry walls have performed well due to in-plane loading, yet despite the advantage of being more aesthetically pleasing, post-tensioned clay brick masonry walls have not been investigated under this loading. Five half scale structural specimens using this system were constructed and tested, and the results from these tests plus a proposed force-displacement analysis procedure are included herein. The results show that post-tensioned clay brick masonry walls are well suited for seismic regions when the walls are grouted and unbonded, and the presence of confinement plates in the compression region greatly enhances the overall performance of the wall. In addition, the force-displacement analysis shows that in order to account for the overall behavior of the wall, cyclic degradation characteristics must be included.







Structural Masonry Designers' Manual


Book Description

This major handbook covers the structural use of brick and blockwork. A major feature is a series of step-by-step design examples of typical elements and buildings. The book has been revised to include updates to the code of practice BS 5628:2000-2 and the 2004 version of Part A of the Building Regulations. New information on sustainability issues, innovation in masonry, health and safety issues and technical developments has been added.