Retrofitted Buildings

1996 ◽  
Vol 12 (1_suppl) ◽  
pp. 219-228
Keyword(s):  
Precast Concrete ◽  
Unreinforced Masonry ◽  
Masonry Buildings ◽  
Northridge Earthquake ◽  
Seismic Strengthening ◽  
Parking Garage ◽  
Computer Based

This section contains information about several buildings that had been seismically rehabilitated before the Northridge Earthquake. Refer to Chapter 5 for reconnaissance information concerning retrofitted tilt-up-wall buildings and Chapter 8 for retrofitted unreinforced masonry buildings. Additionally, there is one retrofitted precast concrete parking garage discussed in Chapter 4. Undoubtedly, many more buildings have been retrofitted than are presented here, but building departments generally do not keep easily accessible records that identify retrofits, so data is difficult to gather. Seismic strengthening should be specifically identified in computer-based building department databases.

Failure of wall–slab joint in unreinforced masonry building

2016 ◽  
Vol 20 (5) ◽  
pp. 759-771 ◽  
Author(s):  
Feng Lin ◽  
Xiuming Yang ◽  
Keyu Li ◽  
Xianglin Gu ◽  
Xiang Li
Keyword(s):  
Progressive Collapse ◽  
Precast Concrete ◽  
Unreinforced Masonry ◽  
Masonry Building ◽  
Masonry Buildings ◽  
Continuous Cast ◽  
Concrete Floor ◽  
Simply Supported ◽  
Floor Slabs

Investigations on buildings severely damaged due to earthquakes or explosions have indicated that unreinforced masonry buildings with simply supported precast concrete floor slabs exhibit deficiencies in resistance to progressive collapse, compared to unreinforced masonry buildings with continuous cast in situ concrete floor slabs. The collapse mechanisms observed in the two types of unreinforced masonry buildings are closely related to wall–slab joint failure. The purpose of this study is to investigate the failure behavior of wall–slab joints and the effect on the collapse of the two types of unreinforced masonry buildings. Six wall–slab joint specimens and eight grooved wall specimens, induced by partial failure of wall–slab joints, were tested under monotonic vertical and horizontal loading. Numerical models were then developed, verified, and used to perform a parametric study. It was found that the wall–slab joints failed in various modes, that is, slab failure, wall failure, and slab pullout failure. The grooved wall could fail in bending or in compression. Analyses indicated that the collapse of unreinforced masonry buildings with simply supported precast concrete floor slabs develops in both vertical and horizontal directions. However, the collapse of unreinforced masonry buildings with continuous cast in situ concrete floor slabs is prone to develop only in the vertical direction, resulting in improved progressive collapse resistance.

Performance of masonry structures during the 1994 Northridge (Los Angeles) earthquake

1995 ◽  
Vol 22 (2) ◽  
pp. 378-402 ◽  
Author(s):  
Michel Bruneau
Keyword(s):  
Los Angeles ◽  
Unreinforced Masonry ◽  
Masonry Building ◽  
Masonry Buildings ◽  
Masonry Structures ◽  
Northridge Earthquake ◽  
Seismic Evaluation ◽  
Masonry Construction ◽  
Reinforced Masonry ◽  
The Impact

The surface magnitude 6.8 Northridge earthquake which struck the Los Angeles area on January 17, 1994, damaged a large number of engineered buildings, of nearly all construction types. As earthquakes of at least similar strength are expected to occur in most of eastern and western Canada, the study of the effects of this earthquake is of particular significance to Canada. This paper, as part of a concerted multi-paper reporting effort, concentrates on the damage suffered by masonry buildings during this earthquake, and explains why the various types of observed failures occurred. The seismic performance of all masonry construction similar to that commonly found in Canada is reviewed, but a particular emphasis is placed on providing an overview of damage to unreinforced masonry structures which had been rehabilitated before this earthquake. To provide a better appreciation of the impact of this earthquake on masonry buildings, and a better assessment of the engineering significance of their damage in a Canadian perspective, this paper first reviews the evolution of building code requirements for unreinforced masonry buildings up to the seismic retrofit ordinances enacted prior to this earthquake. Examples of various damage types, as observed by the author during his reconnaissance visit to the stricken area, are then presented, along with technically substantiated descriptions of the causes for this damage, and cross-references to relevant clauses from Canadian standards and codes, as well as the recently published Canadian Guidelines for the Seismic Evaluation of Existing Buildings, whenever appropriate. Key words: earthquake, unreinforced masonry, seismic rehabilitation, retrofit, retrofitted masonry building, reinforced masonry, buildings, failure, collapse, heritage buildings.

Some Cost Considerations of the Seismic Strengthening of Pre-Code Buildings

1985 ◽  
Vol 1 (4) ◽  
pp. 695-719 ◽  
Author(s):  
Christine M. Platt ◽  
Robin Shepherd
Keyword(s):  
Unreinforced Masonry ◽  
Masonry Buildings ◽  
Seismic Strengthening ◽  
Tax Shelter ◽  
Tax Returns ◽  
Direct Income

Several earthquake ordinances have been enacted requiring owners of pre-1934 unreinforced masonry buildings either to upgrade their seismic strength or to demolish them. In this paper some of the factors which an owner must consider, including the relative costs of rehabilitation and reconstruction, are reviewed and specific examination of the after-tax returns for a hypothetical California building is made. It is shown that whereas there may be little direct income benefit gained from upgrading a particular building, tax shelter advantages may well provide sufficient financial inducement to justify a decision to upgrade rather than to demolish.

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